Attention To Details Solves Phantom Voltage Code

By Mike Greer, Diagnostician

author10Mike has been with Certified Transmission since 1996, and been in the industry since 1987. He is an ASE master Technician and has served as a Master Builder for the company in the past.

 

 

 

 

A growing trend that we have been seeing at all of our repair shop locations involve vehicles that are brought to us when a customer is referred to us by a general repair facility, or brought to us directly by the repair facility for diagnosis. In all cases, the shops are convinced that the vehicle either needs a transmission replacement, or that they feel the vehicle symptoms indicate a problem with the transmission. We have all seen it before when a vehicle shows up with engine misfire that is perceived to be the transmission, or a locked up fan clutch that is making the transmission “slip” or not shift into the higher gears. These types of issues are not going away any time soon, and actually things are getting to be more common as vehicle systems increasingly become more integrated and dependent upon each other to make the whole vehicle work the way it was designed to.

The subject of this article is a 2007 Nissan Maxima that was brought to us from a shop that we do a lot of work with. They had initially called and wanted to see if we could point them in a direction on what to look at. The shop had stated the vehicle had code P0868 (secondary pressure down), but after the code was cleared, it had not returned yet the car was still acting up. It would cut out and go into limp mode. I had asked about any other codes in other systems and they said it had a C1109 code (battery voltage out-of-range) in the ABS module, and the battery had been replaced a few weeks ago. I told them to make sure that the charging system was working properly and get back to me with what they had found.

The next day the Maxima was dropped off after the shop said they had checked out the charging system, so it must be the transmission. The shop uses the same Midtronics analyzer that we do and it has been pretty reliable. After verifying the issue, I started my standard evaluation. I follow the same procedure on every vehicle: check the transmission fluid, check the engine oil, use the pre-scan function on the Zeus workstation to scan all modules on the vehicle, and then check the battery and charging system. My test of the battery/charging system passed, lining up with what the shop had reported. I did pull the same C1109 code that was stored in the ABS module, but the P0868 had still not returned.

I then headed off for a road test. For most of the test drive everything was working well until I got about three blocks away from our shop. When accelerating from a stop the car just acted like it shut down. Throttle input was lost, and then it came back for a second, and then dropped out again. It had gotten so bad that I pulled off into a parking lot and walked back to the shop thinking the vehicle would not make it back on its own.

I checked out a few other vehicles at the shop and then went back to see if I could get the Maxima to make it back, which I did. I scanned for codes again and the C1109 was in the ABS module again. I wondered why the ABS module was the only module to set a code, but the issue seems to be affecting the transmission? I figured that I would just go to the source and monitor the battery voltage at the battery thinking that if anything, I would lose charging voltage due to a bad alternator. What actually happened was entirely different, however.

The voltage shot up past 19 volts on the meter. If you look at the results (FIG 1), each time the voltage goes down to a proper level the RPMs on the engine go up, and when the voltage goes high we lose throttle and the RPMs come back down. That screenshot was the most consistent example I had saved, and it also seemed to happen more consistently when I was accelerating heavier at lower speeds. When I got back to the shop I started doing a visual inspection thinking that the engine torque (torsional movement) was somehow affecting this.

198a

Figure 1

I spotted a two-wire plug on the alternator that did not quite look right. (FIG 2) When I went to unplug it to check terminal fit and to make sure it was not corroded, it simply pulled right off. It was not plugged in all the way! We use a product called Deoxit for electrical connections. It has done a really good job for us for cleaning corrosion, and it also improves conductivity, so I sprayed some of that on the connector and plugged it back in making sure that the locking tab was engaged and went off for another road test.

198b

Figure 2

Everything now was working well with voltage stable and no more cutting out and losing the throttle. I also did an extended road test to see if the transmission code would return and it did not. We called the shop and told them what had happened and what we did, and they were really surprised at the results and wanted to pay the diagnostic charges so their customer did not have any expenses. They called the customer to let them pick up the car directly from us and they were extremely happy that they did not have the expense of replacing the transmission.

It has been a few months since this happened so I had the service advisor call the customer just to see if everything was still working well, and I’m happy to report that no transmission issues have arisen everything was still working as intended.
It’s important to think about all of the conditions that are occurring when an issue exposes itself. In my case, it was the movement of the engine that was making the concern intermittent and elusive. That was the clue that helped crack the case.

Broken Snap Ring Creates OSS Codes

By Chris Adams, Diagnostician

author1Chris Adams started with Certified Transmission in 1986 as an R&R technician, and currently works as our Diagnostic Trainer. His current duties involve training and advising our retail diagnosticians, as well as assisting in the research and development of our remanufactured products. He also holds ASE Master and L1 certifications.

 

 

 

Here in the Midwest the dog days of summer are here, creating a hot, humid environment and the intermittent issues that seem to come with it. You know…the types of concerns in which you have to drive the vehicle for an extended road test, and by the time you see what the issue is and get back to the shop, the heat from the engine compartment or under the vehicle is almost unbearable and you can’t touch anything without heat resistant gloves on. Good times.

That is where this story starts. A 2011 Chevrolet HD2500 6.6L equipped with a LCT1000 transmission came into the shop with a customer concern of no reverse and the indicator under the “R” is flashing. No power when pulling from a stop, and it won’t shift into higher gears on highway. Over the past few months we had seen a rash of bad Allison TCM’s with various different complaints, so I wondered if this might have been the case with this vehicle.

I started the evaluation by scanning all modules for DTCs and I found a P0721 “output speed sensor performance” code, and a P0722 “OSS low voltage” code, so this one appeared pretty straight forward, at first glance. Off I go for a road test intending to focus my attention to the OSS PID, so I set up the scan tool in graphing mode and saw that after about ten minutes while slowing down, the OSS signal drops out. (Figure 1)

197a

Figure 1

When I went to take off from the stop light the truck was in failsafe, so I pulled over and checked for codes and found the P0722 had returned. I went back to the shop to finish the evaluation and take a closer look at the OSS. I performed a battery and charging system test which passed, so I let the vehicle sit for a couple hours while I checked out a few more vehicles. When I got back to it and went to unplug the OSS connector, the locking tab broke right off. The connection looked ok, as I saw no corrosion and the pin drag was good. I then unscrewed the sensor to make sure it was not mechanically damaged in some way, which it was not. I put my finger into the hole to make sure the reluctor ring was not damaged or loose, but I did not really expect to discover anything wrong there since it was a low voltage code I was chasing. It appeared to be ok.

At this point I could have taken a different path, but I don’t think the outcome would have been any different. We have all seen our fair share of these plastic screw in sensors have issues in the past and I had looked over the wire harness routing as per the PI#0339C and did not see anything wrong with it, and we had a sensor in stock so I ordered the repair pigtail from GM and proceeded to replace the OSS and pigtail feeling fairly confident it would correct the issue. After another extended road test, you guessed it…the speed sensor signal dropped out again very similar to the first screenshot, but this time it had set a P0721 code. In retrospect I knew I should have sold diagnostic time to the customer and put a scope on the sensor, so now the diagnosis time is on me.

I connected the scope to the OSS right at the connector and headed out again, not really expecting to see a problem here since it was a new sensor and pigtail. The reluctor was not damaged, so I was really thinking it would end up being a wiring issue or a bad TCM.

After another long road test the OSS signal on the scope and the data PID both dropped out at the same time. What? Did I have a bad “new” sensor? Remember when I said I don’t think the outcome would have been any different? If I would have done this from the start I really think I would have still put a sensor in it.

I brought the truck back into a bay and removed the sensor while it was blazing hot. I think it was about 96°F that day, and I bravely stuck my finger into the t-case to check the reluctor again and I finally discovered the real issue: while the ring would not spin on the shaft (it is splined onto the shaft), it did slide forward and backward. Figure 2 shows when I pushed it forward, and Figure 3 is when it was pushed back toward the driveshaft.

197b

Figure 2

 

197c

Figure 3

When it was forward the teeth were barely in the middle of the hole, and the sensor pickup is only about a 1/8th wide. This appeared to be the issue. I put it back together and went out again to try to verify it, and was able to. Look at each one of the dropouts when I quickly applied the brakes. (Figure 4) This confirmed that the issue was inside of the transfer case. After the transfer case was removed and I pulled the rear case half I could see what had happened: the snap ring on the backside of the rear bearing was broken into pieces. (Figure 5) This allowed the output shaft to slide forward just enough so that when the reluctor was at the forward end of its travel, it was enough to move it out of the sensors range and lose the signal. We ordered a couple snap rings and a rear bearing, made sure all the pieces of the broken snap ring were accounted for, and put it all back together. Now working as designed, no codes returned and we were able to deliver the truck back to the customer.

197d

Figure 4

 

197e

Figure 5

Expect the unexpected.

Mopar Fix for RAM ProMaster Transmission Bracket Breakage

By Chris Adams, Diagnostician

author1Chris Adams started with Certified Transmission in 1986 as an R&R technician, and currently works as our Diagnostic Trainer. His current duties involve training and advising our retail diagnosticians, as well as assisting in the research and development of our remanufactured products. He also holds ASE Master and L1 certifications.

 

 

 

One of our retail locations had a 2015 Ram Promaster show up on the back of a tow truck a few weeks ago, and this truck is a service vehicle for a local grocery store. The driver said he was traveling at about 40MPH when he felt like he ran over a boulder in the road, heard loud noises, and the truck stopped moving. This is the first time that I have seen this happen; the transmission was hanging down so far it was almost on the ground. What the heck happened?

We carefully pushed it into the shop so we could try to raise the transmission up and secure it so no more damage could occur, it almost appeared that the heater hoses were the only thing holding it up as they were stretched tight. After we were able to get the transmission lifted up and secured with a chain we were then able to see what happened, the left transmission (Chrysler calls it an engine mount) mount bracket and the transmission case were broken. There was a lot of damage done: case broken, mount bracket broken, both axles were damaged, shift cable broken, and air intake tube was torn. What we did not know yet is what caused this to happen. These photos were taken before we removed the transmission.

Figure 1

 

Figure 2

 

If this vehicle was traveling down the highway I’m sure it could have been much worse. There were wire looms that were at the verge of possible damage if it had dropped any further. We needed to find out why this happened and take the appropriate steps to make sure that it did not happen again. In a situation like this, if the root cause isn’t discovered there is a high probability of a customer comeback and another damaged transmission case.

We first looked for TSBs and came up empty, so I then contacted our technical director that is in charge of this unit model at our remanufacturing facility and asked if we were seeing cores come in that were broken like this. Sure enough we were, and he also informed me that the case for this particular application was just recently made available for sale from FCA. It was pretty clear that this was more of an issue than what I was initially aware of.

The next step I took was to call our local FCA dealer to check parts availability as I just wanted to make sure that everything was available to fix this vehicle before I turned this over for the service advisor to sell the job. This is where having a good parts professional to go to is always a good thing! After I gave him the VIN number and the parts that I needed, he said, “Hold on there are some notes on this one.” He then provided me with the paragraph below:

ALSO: This applies all Promaster (VF) 3.6L/62TE equipped vehicles. If the transmission bracket to the transmission case fasteners is removed during servicing, the fasteners (Part Number 06511385AA) are one time usage, and must be replaced. Vehicles built prior to 10/23/2015 require Service Kit PN 68461214AA; includes Transmission Isolator PN 68264483AA, and Adaptation Bracket 68264479AA, Fastener Service Kit PN 68329056AA. Vehicles built after on or after 10/23/2015 will require only the Fastener Service Kit PN 68329056AA (Please note that part #’s are subject to change, please check with your parts supplier) The production date on the vehicle we were working on was before 10/23/2015, so according to the notice we knew that we needed the complete service package.

With this newfound knowledge in mind, I was fairly confident that we could install a remanufactured transmission along with the updated parts and not have this issue after we completed the repairs. What I didn’t know at this point is exactly what was changed with the new bracket, isolator, and bolts.

Figure 3

 

This is the updated bracket compared to the OE piece, and it’s hard to tell from the picture but the new one had a lot more mass to it.

Figure 4

 

This is one of the new side bolts which are longer, have threadlocker compound on it, and even have some type of lubricant between the washer and head of bolt which I presume is for a more accurate torque reading. You will also need to remove the left headlight to properly torque the top mount bolt.

Please refer to service information for the complete procedure to install the mount, but I will cover the highlights here:

Note: Mopar lock & seal adhesive must be used on mount fasteners to prevent vibration loosening.

  1. Hand start all five transmission bracket bolts, starting with the lower four and then the upper bolt.
  2. Using four NEW bolts, beginning with the two outer, tighten all four side bolts to 77 ft-lbs.
  3. Tighten upper transmission bracket bolt to 46 ft-lbs.

I believe that if you were to tighten the top bolt before the side bolts, this would create undue stress on the case and bracket.

What I believe causes this issue is the mount bracket bolts coming loose; it is really hard to come to a 100% conclusion when they come in all broken apart like this but I can see evidence of movement of the bracket. In these photos you can see some wear on the boss that mates with the case, and there are thread grooves cut into the aluminum from the bolts which I would only think would be possible with movement of the bracket.

Figure 5

 

Figure 6

Programming Steps for 8L45/8L90 Units, Post Replacement

By Daniel Skinner, Diagnostician

author5Daniel is a Diagnostician for Certified Transmission’s Blue Springs, MO shop.

 

 

 

 

 

Quite a lot has been been written and many technical classes have been put on regarding the General Motors 8L45/8L90 family of transmissions. We are now seeing opportunities to put that information to use. The vehicles equipped with these transmissions are beginning to trickle into our shops as they are beginning to fall out of factory warranty. Many GM vehicles utilize these transmissions from 2015 to present.

Our first vehicle to come in with 8L90 problems was a 2016 GMC Sierra 4×4. The truck had 103,000 miles on the odometer. The customer’s complaint was that the vehicle had a “shake” feeling below 70 miles per hour. He also that there was a “rumble” feel occasionally.

When evaluating the vehicle I noted that there was a P0711 (transmission fluid temperature sensor “A” circuit range/performance) code present. The transmission fluid was dark red with a slight burnt smell. During the road test I was able to reproduce the customer’s complaint. I experienced a repetitive, systematic vibration and droning sound throughout the vehicle at highway speeds. I was able to capture the issue using the scan tool.

196a

Figure 1

This photo illustrates (Figure 1) TCC slippage and the TCM attempting to compensate/correct for it. The rhythmic shudder I experienced coincides with TCC slip speed captured with the scan tool. The transmission fluid temperature shown on the scan tool also explains the P0711 code. A sudden change in fluid temperature (50?F or more within 8 seconds) will cause P0711 to set. Obviously the transmission fluid temperature reading on the scan tool was unstable, so an electrical system analysis was performed to ensure battery and alternator integrity. Excessive AC ripple can play havoc on any electronically controlled transmission. A pan inspection was performed; evidence found in the pan along with the fluid condition had eliminated the possibility of trying to flush out the fluid with the Mobil 1 LV product, per a GM TSB.

At this point the customer agreed to replace the unit per our recommendation. After the unit was installed, solenoid valve characterization reprogramming had to be done. This is required when replacing 8L45/8L90 transmissions, and accomplished through General Motors’ TIS2Web Service Programming System (SPS). When performing solenoid valve characterization reprogramming, it is crucial to have a good clean power source connected to the vehicle’s battery and have all vehicle accessories turned off, as with any other programming procedure. Solenoid valve characterization reprogramming is fairly straightforward. After logging into the SPS website and purchasing a subscription for programming the vehicle you are working on (programming subscriptions are VIN specific), SPS will verify the vehicle/VIN you are working on. After SPS completes the verification, you will be directed to the screen shown in figure 2:

196b

Figure 2

Highlight “K71/Transmission Control Module” in the “Select Controller” area. Then select “MCVM (Mechanical Characterization and Virtual Matching) Operations” in the “Select Function” area. Verify that the RPO code given coincides with the vehicle you are programming. Finally, be sure you select “Solenoid Data Characterization” in the “Select Programming Type” area at the bottom of the screen, and click “next”. The next screen will be the “MCVM (Mechanical Characterization and Virtual Matching) Operation Selection” screen (figure 3). Here you will be prompted to select what operation to be performed. In this case I chose “Replace Transmission”, as the unit had been replaced. Clicking “Next” will move you to the next screen (figure 4). Here you will enter the TUN (Transmission Unique Number).

196c

Figure 3

196d

Figure 4

This number can be found on a sticker on the right side of the transmission as seen in the “Transmission Identification Information” section of the screen. After entering the TUN and clicking “Next”, SPS will then begin the programming operation and prompt you when the process is completed. SPS seems to be user friendly regarding this process. I had no issues getting through it for the first time. At this point it is also recommended that the ECM (Engine Control Module) is updated to the latest calibration. The ECM on this particular truck happened to be up-to-date.

The next step in the process is to perform a “Fast Learn”. This clears all adaptive values in the TCM. Using your scan tool, follow the on-screen instructions precisely. Keep in mind that if at any time in the process, there is an interruption; you could experience a false neutral condition with the transmission. If this happens, you will have to disconnect and reconnect the TCM to correct the issue.

On the initial road test after installation, I experienced very minimal flaring during shifts. This flaring cleared up within a few miles of stop-and-go driving. This may vary from vehicle to vehicle. When rechecking the fluid lev-el, the transmission fluid level must be brought up to 194?F to ensure that the thermal bypass valve is open, if so equipped. Allow the fluid temperature to cool back down to 95-113?F. With the engine running, remove the transmission oil level plug from the transmission pan. At the correct level, fluid should drip from the check plug hole.

On the final road test, I monitored “TCC Slip Speed” and TFT (Transmission Fluid Temperature) with the scan tool. As you can see in (figure 5) the TCC slip speed is smooth and now normal. The TFT was stable as well. A post scan also confirmed that no codes reset.

196e

Figure 5

Other than routine maintenance, this was the first major 8L90 issue we have dealt with. In the near future, I foresee many more 8L45/8L90 transmissions showing up. The torque converter issue we experienced on this vehicle is a problem that many dealerships have already encountered. Don’t be surprised to see these vehicles begin to show up at your shop, if they haven’t already.

Careful Visual Inspection Saves Time

By Travis Kraus, Diagnostician

author35Travis has been in the transmission business since 2003. He is from Topeka, KS and got his start at his dad’s shop sweeping floors. He came to Certified Transmission after 10 years as a transmission tech at a Ford dealer, and he has the A2 and A3 ASE Certifications and is working on more.

 

 

 

A customer showed up at our shop with a 2008 Chevrolet Impala SS that was equipped with the 5.3 LS engine and a 4T65E transmission. The customer had a complaint of an erratic speedometer while driving. I began by collecting all the vehicle information for a check out sheet, such as VIN, mileage, engine, and transmission type. After filling out the vehicle information section I set about to begin my diagnosis. First I checked codes and found the vehicle had no transmission or engine codes, but it did have a RF wheel speed sensor code which did not seem likely to cause the problem, but I kept this in mind anyway. I was suspecting a possible output speed sensor issue or maybe even an instrument cluster issue.

I set up my scanner to monitor certain transmission PIDs such as TCC duty cycle, TCC slip, gear command, RPM, and the output speed sensor (among others) and set out for my road test. At first the vehicle did not act up and I was starting to wonder if it even had a problem. After a couple of miles, sure enough the speedometer jumped back and forth a few times spiking as high as 60-70 mph just shortly after beginning to move; no way could this be correct. Every time this happened was when I took off from a stop, and this was a pretty good clue for me.

This told me I likely had a short somewhere and when the engine torqued it would cause the short and the malfunction. With this information in mind I returned to the shop and attempted to duplicate the issue by power-braking the vehicle quickly while in gear. Sure enough, I was successful in replicating the issue in the shop. You can see on the attached screen shot of the scanner when the problem occurred. (figure 1)

194a

Figure 1

The vehicle speed PID goes from zero to 23 MPH instantly and the output speed sensor goes from 0 to 1010 RPM at the same time. I wanted to rule out possible interference from the alternator so I ran an electrical system check and ripple test which is standard operating procedure here, and no problems were found with the charging system. After this I decided to raise the vehicle and start looking for other possible causes. In the past I have seen internal transmission failures that drop large amounts of metal debris. This debris will stick to an output speed sensor and cause erratic readings of the output speed sensor.

I unbolted the speed sensor and pulled it out of the case and it was clean with no signs of concern, so I reinstalled it and started looking elsewhere. I always like to do a very good visual inspection before I break out the DVOM and do electrical checks. Many times I have found a concern with just the solid visual inspection. I started to follow the wire harness from the sensor back to the PCM. I noticed the plastic conduit surrounding the harness near a metal bracket on the transmission that secured the harness in place had deteriorated and fallen off. (figure 2)

194b

Figure 2

I knew I was onto something with that discovery, and upon closer inspection I discovered a couple of wires had been chafed through the insulation and bare wires were exposed and grounding on the metal bracket. (figure 3)

194c

Figure 3

Next I set off to identify these wires hoping to find they were a part of the output speed sensor circuit. I pulled up a wiring diagram for the output speed sensor on this car and identified the circuits as being a purple wire and a yellow wire as a twisted pair. With this information I went back to the car and as you can see in the picture, I had a chafed purple wire in a twisted pair with a yellow wire. This was certainly my problem. With my diagnosis complete I turned in this information to the service advisor to sell the work. The customer was happy to hear it was likely a simple problem and gave us the authorization to repair the wires and recheck.

At the initial inspection we did a pan inspection and the pan was clean and just had some old-looking fluid inside. We serviced the transmission and set off to repair the wire. We repaired the chafed wire and wrapped it back up with electrical tape and put some new conduit around it to protect it and prevent this from happening again, then secured it back in the bracket. With the service and repair complete and everything buttoned up, I set back off on a post-repair test drive to see if the problem was fixed. Everything worked as designed and the speedometer never exhibited a glitch again. I was happy with this so we notified the customer that his car was ready to pick up. The customer was eager to get his car back and get on the road with it.

We waited a couple of days and gave the customer a follow-up call to see how things were going with the impala. The customer was very happy and reported the car was working great and has not acted up since. The moral of this story is to never under estimate a good visual inspection. I have found many problems without the need to go into in-depth testing simply by looking around and paying attention to the small details such as plastic conduit that has fallen off a wire loom.

Battery Corrosion Can Cause Odd Electrical Behavior

By Paul Loch, Diagnostician

author22Paul has been with Certified since 2010 but had many years of experience in the general repair industry prior to joining our team. He started with us by doing R&R work and then trained to be a diagnostician, which is what Paul is currently doing at our Bellevue, NE location.

 

 

 

A customer had brought in her 2010 Ford Escape equipped with a 3.0L Engine and the 6F35 transaxle. The customers concern with the vehicle was that the transmission slips intermittently. We started our evaluation with a quick visual inspection of the vehicle and checking fluids, all which check out good. Then I scanned the car with the scan tool; all of our locations have Snap-On Zeus workstations and I had two codes: a P0297, “Vehicle Over Speed Condition”, and a P1500, “Vehicle Speed Sensor”. No codes in any other modules. The next step was to go for a test drive and see if I could duplicate the complaint.

When cold, the vehicle worked correctly for about 10 minutes of driving, then out of nowhere the transmission acted like it had a mind of its own by shifting erratically. I also observed the speedometer going up and down while maintaining steady speed. I pulled up the output speed sensor PID on the scan tool and found it also was reading all over the place. (Figure 1) is from a startup without moving at all. I brought the vehicle back to the shop to do a visual inspection, and when I opened the hood I found the battery terminals were severely corroded, the fluid was slightly varnished and reddish brown in color, but had no burnt odor. I have had several speed signal issues before that I had resolved with cleaning the battery terminals and the grounds connected to it, so I figured it needs to be done anyway and could possibly take care of the issue.

193a

Figure 1

I cleaned the battery terminals and performed the battery and charging system test. It had passed and did not even pick up any AC ripple, which kind of surprised me because I expected to see erratic test results here. I went for another test drive and it was still acting the same way. Upon returning to the shop again I brought up service information on the PC and checked to see if any TSB’s were available for either of these DTCs, and none were found relating to this particular issue. I also looked at a few other resources I have access to and again found nothing.

The next step was to get into some in-depth electrical testing. I printed off the appropriate wiring diagram so I could see how the circuit works and what to expect. I also printed off the diagnostic flowchart; the flowchart for the P0297 did not reveal much information and the one for the P1500 was going in different directions depending on the application. To make matters worse, the information was confusing due to the pin numbers not matching the connectors on my application. After I got that all straightened out and I knew what I was looking at, I continued on with my testing.

I checked to see if I had good battery voltage for the sensor at the case connector and it checked out fine. Next I wanted to make sure the ground circuit was good since the battery had a lot of corrosion. I only had 0.05v voltage drop on that circuit which is a good ground, so I knew that was not the cause, either. I decided it was time to get the scope out and take a look at the speed sensor signal circuit, so I back probed the circuit at the PCM to see if the signal was good going into the PCM. It was a not a clean square wave signal at all, never reaching 12V and also not pulling all the way to ground (Figure 2). So I went to the case connector and back-probed the same circuit and tested and the signal looked more like what I was thinking it should look like (Figure 3).

193b

Figure 2

193c

Figure 3

I now knew that I have a bad signal at the PCM and a good signal coming out of the unit, so my conclusion at this point was that there was an issue with the harness somewhere between the transmission and the PCM. I removed some components to gain access to the harness. After removing the battery and battery tray I noted that there was a lot of dried up corrosion in the battery tray as well as underneath it. Directly below the battery tray is where the harness was routed and I saw signs deterioration of the electrical tape and split loom. Could this be where my problem was? I then removed the taped and loom to expose the wires where I noticed the insulation on some of the wires didn’t look quite right, and appeared swollen (Figure 4).

193d

Figure 4

Back to the scope, I used a wire piercing lead and connected on the TCM side of the “swollen” wire (Figure 5) and had a good signal, then connected to the PCM side expecting to see the bad signal just like I had at the PCM, but did not; the scope reading looked normal. I really thought I had nailed down where the problem was, and visually I was not seeing anything else that looked out of place. I then realized what I had done; I had changed something didn’t I? Yes, I did. These wires were all taped up tightly before I took the wire covering and the tape off, so I connected my lead back up to the PCM side of the loom and grabbed a hold of the wires where it looked damaged. I could get the scope pattern to change just depending on how hard I clenched my fist. (Figure 6) is a close up of one of the wires in question.

193e

Figure 5

193f

Figure 6

I carefully split the insulation to get a closer look at the inside of the wire. Upon getting the insulation split open I found a couple wires that had heavy corrosion. The worst one was circuit VET26 which was the output speed sensor signal to the PCM. I then cut out the bad section of the wires and installed new wires in their place. After the repairs were made I rechecked the signal at the PCM and it was now very clean. The vehicle now performed correctly on the test drive. While the wire inside the insulation was corroded, I do believe that it was more in the breakdown of the wire insulation not being able to shield the wire from induced voltage than the corrosion of the wire itself.

It’s pretty common for the obvious issues (corroded battery and tray) to point you in the right direction when it comes to strange electrical issues. It’s always a good idea to address these obvious issues first, and check the general area around it. Doing so can save a lot of unnecessary diagnosis time when dealing with electrical gremlins such as this.

 

BATTERY ACID AND CUSTOMER MODIFICATIONS CAUSE TRANSMISSION PROBLEMS

By Carman Klaber, Diagnostician

author26Carman has been in the transmission industry his entire career, and has been with Certified Transmission since 2003. He has held ASE certifications for over 25 years. He is married with two children, and enjoys camping and riding ATVs.

 

 

 

I wanted to share with you a couple of situations that I have run into over the past couple months. The first one is a 2010 Lexus RX350 that came in on the back of a tow truck. This SUV is equipped with a 3.5L V6 and a U660E transaxle. The customer had it towed because the vehicle was in failsafe mode. When I began the evaluation, the first thing I noticed was the strong odor of battery acid when I opened the hood (figure 1).   One look at the battery and I knew this was going to need to be addressed, but at this point I do not know what is causing the failsafe problem. When the scan tool was connected I discovered that I had no communication with the TCM, but did have communication with all of the other modules.

192a

Figure 1

All of our initial diagnostic evaluations include a battery and charging system test. I’ll bet you can guess the outcome of this one; the battery failed, but the alternator had passed. At this point we informed the customer that some electrical testing was going to be necessary in order for us to find out what was causing the problem. The customer agreed to that and we then proceeded with the job.

I am sure that you guys have seen these vehicles in your shop and know that the battery is positioned directly above the transaxle, so knowing that and the fact that the battery had evidence of leaking acid, I knew where I was headed. The TCM is mounted directly on top of the unit and plugs directly into the transmission case connector. I started by checking power and grounds on the vehicle harness to the TCM and found everything in order. I disconnected the harness and everything looked good with no corrosion or pin-fit connection issues. Next I removed the two bolts that hold the TCM to the case. The TCM just fell off onto the floor, and I was not expecting that! The case connector and the TCM were corroded so badly that four of the pins and the plastic housing were stuck in the TCM. I think I found the problem! (figure 2 & 3) My next move was to recommend a pan inspection to see if there was any need to go inside the transmission, or just replace the internal harness and TCM. After dropping the pan it looked good inside, no clutch material or excessive metal. I then recommended replacing the internal harness, TCM, battery, and a transmission fluid flush.

192b

Figure 2

 

192c

Figure 3

The parts were a couple of days out, so while I was playing the waiting game I cleaned the area as best I could and installed the new battery. When the parts arrived I pulled the valve body down and replaced the internal harness, installed the TCM, and flushed the transmission fluid. The TCM came already loaded with the calibration so all I needed to do was the initialization procedure, reset memory as Toyota/Lexus call it, and go for a road test. The transmission shifted as it should and I couldn’t be more pleased. The customer was also pretty happy that they did not need to replace the transmission.

The next vehicle I wanted to discuss had an issue that you will not see that often. The car was a 2006 Hyundai Tiburon with a 2.0 liter 4 cylinder with an A4BF1 transmission. While going through the initial evaluation and connecting the scan tool, it had a DTC stored for P0711 TFT signal abnormal, but no other codes. The customer concern was that everything seemed to work fine but, the CEL light would “come and go”.

With the scanner attached and the transmission data PIDs on the screen, I could see that the transmission temperature was 45ºF which was fairly close to the ambient temperature at the time. That, coupled with the customer concern, I was expecting an intermittent issue. As I took off on the road test the transmission shifted well but the TFT PID never went above 45ºF, so therefore the TCC never engaged. This appeared to be what was causing the code to set, so I needed to find the root cause of the issue. After returning to the shop and pulling onto the lift, I started taking a closer look in the area of the transmission and noticed an extra red wire in the loom to the mass air flow sensor, as seen in the photo. (figure 4)

192d

Figure 4

After peeling the tape and wiring loom off the red wire, I could see that it was spliced into the yellow/black wire in cavity #5 of the MAF sensor pigtail. The other end of the wire was spliced into the gray wire cavity #1 of the transmission case connector, which is for the TFT sensor. (figure 5)  I talked to a couple of colleagues about this but they had never seen nor heard of this scenario. I even tried the tech support search, but nothing came up. My theory is they were trying to trick the ECM into thinking it was running cold so it would richen up the fuel mixture and supposedly get better power and performance. I just could not figure out why we went to the transmission temp sensor. Maybe they were trying to have the IAT temp and transmission temp match? I wish I knew what went through some of these people’s thought processes.

192e

Figure 5

After returning everything back to a factory configuration, I serviced the transmission and went for another road test. Watching the scanner, the TFT sensor was rising as it should, and when it was warm enough the TCC would now engage as it was designed to. We called and let the customer know his car now works like it should and he was happy that the source of the intermittent CEL was solved. Both cases could have turned out worse for the customers, but a happy customer means repeat business.

Sometimes Even New Parts Can’t Be Trusted

By Randy Peterson, Diagnostician

peterson-randyRandy has worked for Certified Transmission for over twenty four years and is an ASE Certified Master Technician, including L-1. He has been in the automotive industry for over 30 years.

A customer brought her 2006 Chrysler PT Cruiser to our shop with a complaint of random high engine revs. She stated that restarting the engine resets the vehicle and it works again temporarily, and this had been going on for about four months. The vehicle had a 2.4-liter turbocharged engine with a 604 transmission.

The diagnostician performed the initial road test and collected some preliminary information. There were diagnostic trouble codes stored in the PCM. This was an NGC 4-plug computer, so the ECM and TCM are in the same module. The codes stored were P0700 (turns on the MIL), P1684 (battery was disconnected), and P0882 (TCM power input low). He was unable to duplicate the symptoms on the initial road test. There were also radio communication codes stored because the radio was not the factory radio. It also had an external audio amplifier and big subwoofers. At this point he was not sure if this is related, but took note of it. There was also a leak noted at the transmission pan, as well as a negative battery terminal in poor condition. The diagnostician recommended more diagnostic time to investigate the P0882 code and reseal the pan. The customer authorized the diagnostics and transmission service.

Battery connections are crucial in today’s vehicles. A small amount of voltage loss can wreak havoc. The first step was to correct the connection problems. He replaced the negative battery terminal with a factory type cable end crimped onto the cable. The transmission was serviced to solve the leaking transmission pan, and the codes were cleared. The PCM calibration was checked and confirmed that it was up-to-date. The technician then drove the vehicle on multiple road tests to ensure the DTC would not reset. Confident that the poor battery connection solved the problem, the vehicle was delivered back to the owner that Friday afternoon.

The next Monday the vehicle came back. The owner stated that the light came back on and the vehicle quit shifting. The owner left the vehicle for us to check out. The technician ran the codes and the same P0882 was stored. An electrical system analysis was performed to confirm the battery and the charging system were functioning properly. It was time to look deeper into the P0882 code. A look at the repair manual would help us understand more about how the system works and conditions that cause the code to set. Per the manual:

Theory of Operation

The Transmission Control Output circuit is used to supply power to the Transmission Solenoid/TRS Assembly and to the PCM when in normal operating mode. The purpose of the Transmission Output circuit is to allow the Transmission Control System to turn off the power to the Transmission Solenoid/TRS Assembly in the event that the transmission should need to be placed into “limp-in” mode due to a DTC.

After a PCM reset, (ignition switch turned to the run position, or after cranking the engine) the Transmission Control System verifies that the Transmission Output circuit is open by checking for voltage on the Transmission Output circuits before the Transmission Control System request for the circuit to be powered up. The request is sent by a direct circuit control from the PCM to the TIPM. If the Transmission Control System detects less than 3.0 volts when the output is commanded on, the DTC will set.

Note: Inadequate Transmission Control Output voltage can also cause DTCs P0846, or P0871, to set. This does not indicate an internal transmission or solenoid/TRS problem. Repairing the P0882 fault should also eliminate the related DTCs.

When Monitored:

When the ignition is turned from “OFF” position to “RUN” position and/or the ignition is turned from “START” position to “RUN” position.

Set Condition:

This DTC is set when there is less than 3.0 volts present at the transmission control output circuits located in the Powertrain Control Module (PCM) when the Transmission Control System requests the power up of those circuits. Note: Due to the integration of the Transmission Control Module and the Powertrain Control Module, both systems have their own power and ground circuits.”

It seemed a little confusing. It took a few minutes and wire diagram to wrap my head around it. Basically, the PCM turns on the “relay” inside the TIPM to energize the solenoids. It also sends B+ back to the PCM on the same circuit to let the PCM know everything is “ON” and has no faults. If there was a fault and the TIPM turns off the solenoids, the PCM loses its B+ and registers a fault. (Figure 1)

191a

At this point we then decided to check to see if the B+ to the solenoids was present. This was an intermittent issue and it took several test drives for the problem to occur. Voltage was monitored with a DVOM at the PCM pin 28 (relay control out). When the problem occurred, the voltage went from B+ to 0 volts. According to the scan data, it appeared the TIPM was shutting off the power. Could there be an issue with the solenoid circuit? Testing concluded the solenoids and their circuits were good. Next, we need to know if the PCM is turning the trans control relay off. Pin 18, (transmission control voltage) was monitored. After several more test drives the code reset. Power to the TIPM, pin 18, was present at the time of the fault but, there was no power to the solenoids or to pin 28 at the PCM. (Figure 2)

191b

It was concluded that the TIPM was at fault. Since the relay is internal to the TIPM we could not test or jumper the relay. A remanufactured TIPM was ordered from the dealer and installed. The vehicle was driven several more times and seemed to be fixed. The customer picked the vehicle up Friday afternoon.

I wish the story ended there, but it didn’t. Monday the vehicle came back once again. As before, the warning lights were on and the transmission was not shifting. P0882 was stored but there was a new code that had not been there previously, P1603 (PCM internal dual-port ram communication failure).

This basically tells us there is an internal failure in the PCM. We need to check powers, grounds, and perform a wiggle test with the circuit live. No external problems were found so a replacement PCM was recommended. The customer opted for a used PCM. We installed the used PCM, updated the VIN and programmed it to the latest calibration. In the back of our minds was the thought, could this have been the source of all the P0882 issues? An internal PCM problem? After a week of road testing, the code had not reset. The customer picked the vehicle up just to bring it back an hour later.

It seemed that we still hadn’t conquered the P0882 code. We replaced the TIPM and the PCM. What else could it be? So many times we replace a component only to have the same problem. So, we assume the component is good because we just replaced it. We skip over the diagnostics to try and condemn something else. Continue where we left off. I have been guilty of this more times than I would like to admit. We have the same code, same symptoms. We could not assume anything and had to start from beginning. So, that’s exactly what we did.
Step one, attach scope equipment and start testing all over. We are now using a scope so we can see voltage over time. This should tell us which circuit is giving up first. (Figure 3)

191c

Now the code is setting about every other key cycle. While watching the Transmission Control Output we can see B+ dropping off. Shortly thereafter, we see the PCM turn off the B+ to the TIPM. (Figure 4)

191d

So why is the voltage dropping out? Is there a problem the TIPM is seeing? It didn’t appear so. If there was an issue with a solenoid or circuit, the voltage would be cut off immediately and not gradually/erratic cycle off like we saw in the scope capture, and we would likely have a DTC from the guilty component. We are going to test everything again anyway.

Again, we are going to test all the circuits controlled by the Transmission Control Output. We had no solenoid codes, but we were not going to assume anything at this point. So as to not to overlook the grounds, we performed a voltage drop test. We tested at the G104 grounds and got a reading of .008 V with the engine running.

With connector C10 disconnected from the TIPM and the C4 connector disconnected at the PCM, a resistance test was performed on each of the solenoids. I do not like to rely on resistance measurements alone, but since the circuit would not stay alive long enough to run the test through the scan tool and we could not jumper the relay, we had to settle for this test. Each of the circuits passed the resistance test without issue.

Once we determined nothing outside the TIPM was causing the issue, we condemned the TIPM. We called and had our faulty TIPM exchanged at the dealer. The TIPM was installed and the vehicle was driven. We drove the vehicle every day for over a week and the code did not return. We crossed our fingers and returned the vehicle to the customer. It’s been well over a month now and happy to say we have not seen it back.

Second-guessing the parts we install is a tiresome prospect. In cases like this, sometimes it’s the only option left to pursue. While it may make you feel like you are simply repeating diagnostics and the exercise is redundant, it may be the only way to solve the issue for your customer. Stay positive, and stay with it. Assume nothing. Just because a part is new, doesn’t mean it’s good.

Never Overlook The Basics

By Kevin Wayne, Diagnostician

author34Kevin is a Diagnostician at our Liberty, MO Certified Transmission location. He has been with the company since 2014. Kevin has been in the automotive field for 24 years, specializing in engine, transmission and electrical diagnostics. He is an ASE Certified Master Technician with L1 advanced level diagnostics certification.

 

 

 

Like many of you, this time of year I am usually asked to assemble a variety of items and gifts for my family members. In light of these requests, I have spent a significant amount of time analyzing why we waste so much time assembling, dissembling, and re-assembling items out of an unwillingness to simply read the instructions; many times this process results in leftover spare parts and frustration.

I often marvel at how this happens, considering the detailed product resources typically provided by the manufacturer. This information usually contains step-by-step instructions that, when followed, virtually guarantee success. Yet, whether due to pride, an attempt to save time, or simply thinking we know better, more often than not we fail to take advantage of this information. It is this concept of properly using information that I wish to apply to the diagnostic automotive field.

We often spend time projecting what we believe is going wrong onto the vehicle diagnosis, rather than diagnosing the vehicle with an open mind and allowing the vehicle to dictate the direction we should go. We fail to look up the information necessary because we assume we understand what is happening. When there are not direct, step-by-step instructions on what the problem is, almost all of us have a way of gathering information about how a system works. These might include wiring diagrams, apply charts, and Passbooks with information and notes added to them from previous experiences. Time, money, and effort are wasted when we fail to develop a systematic approach to the diagnostic process. A systematic approach is a step-by-step process which is followed the same way each time, allowing the vehicles facts and symptoms to dictate the direction you go.

In order to develop this step-by-step process, one should have a written sheet of the exact vehicle symptoms presented alongside an apply chart, applicable diagnostic sheets for codes, wiring diagrams, and system operation information. By spending time gathering information and working through the problem on paper before ever taking anything apart on the vehicle, you can quickly come up with a approach that should include starting with the quickest, easiest checks first and working your way to a more detailed or intrusive test if needed.

I have found that it is so much easier to quickly eliminate the things that can’t cause the problem when all the information is sitting right in front of you. This allows a visual, more accurate picture of how the specific problem you are having could have been created. Additionally, this process narrows down the problematic possibilities, leaving a list of fewer things that could be a potential cause. Recently I encountered a situation that I believe adequately illustrates my thoughts.

The vehicle was a 2003 Chevy 2500 pickup with a 6.0 liter engine and a 4L80E transmission. Upon its arrival, I was informed that the vehicle had been to two previous shops before arriving at our shop. This truck was an old farm truck and had been treated as one might expect a work truck to be treated. The customer?s complaint was the vehicle staying in a lower gear at times, and also had erratic shifts. The first shop replaced the transmission first with a used unit, and then recently rebuilt one. The symptoms remained the same through the transmission changes, and led to the customer becoming aggravated and taking it to a different shop.

The new shop replaced every electrical component inside the pan in an attempt to solve the problem. This also had no effect on the complaint, which resulted in the shop recommending the customer to bring it to our facility.

Upon test-driving the truck, I noted that it would shift into the 1st, 2nd, 3rd, and 4th gears, but a little on the firm side. After achieving 4th gear (which it would only do for 2 to 5 seconds), the transmission would quickly go back into 2nd gear and stay there until I brought it to a stop. As I started through the gears again, the exact same pattern would happen. Once it downshifted to second, it would not come out unless I brought it to a complete stop. I also noted that as I downshifted out of overdrive the transmission would shift into 3rd gear.

While staying out of overdrive, if I came to a stop and took off again it would shift 1st through 3rd just fine, and worked as designed. The transmission was setting a p1860 Torque Converter Clutch PWM solenoid circuit code and the fluid appeared to look brand new. While on the initial test drive I took my scanner and had the screen customized to show specific PIDs, solenoid 1-2, solenoid 2-3, input and output speed sensors, vehicle speed, gear commanded, and gear ratio. According to solenoid data, the transmission should have been shifting normally based on the solenoid signal commands. ( Figure 1 )

1812a

Figure 1

This screenshot is from the truck when it was stuck in second gear. Next, I sat down with my check-out sheet and retrieved a copy of an apply chart from my 4L80E Passbook, a complete transmission circuit wiring diagram, and diagnostic code description sheet for the P1860 code. The first thing that stood out to me when looking at the apply chart was that in this transmission, both solenoids off would be 2nd gear. (Figure 2) In like manner, both solenoids on makes 4th gear.

1812b

Figure 2

Armed with this information I was already starting to believe that I had a ground or power problem; when both solenoids are energized it would be drawing max current, and obviously no current would be 2nd gear. As I looked at the wiring diagram and code information I noticed that all the solenoids got their power from one source, including the torque converter clutch solenoid of which I have a DTC for. Based off this quick information, I already have a really good idea of what I want to test first. ( Figure 3)

1812c

Figure 3

I decided to test voltage to all the solenoids at the ignition fuse 0 in the fuse box. To me this seemed to be the fastest and easiest test and would lead me to the cause of my problem.

I removed the fuse cover and used my voltmeter to check voltage at the fuse (Figure 4). Sure enough, I only had 4.98 volts key on. If I played with the ignition switch, voltage would vary but would never go over 6 volts. This would obviously cause the problem that the truck is having. Voltage is enough to fire each solenoid individually but when both are commanded on, current is insufficient to operate both solenoids at the same time and it then goes into second gear.

1812d

Figure 4

I recommended an ignition switch 23 minutes after I climbed into the car for a test drive. The ignition switch was replaced and the transmission shifted normally with no codes.

I know this is a problem many of you may have seen before. The diagnostic process was basic. However, keep in mind that this vehicle had been to two other shops and the customer had spent a significant amount of money and time attempting to solve the transmission problem. I believe this was due to a lack of organization by the other shops and failure to gather enough information about what exactly was going on. Rather than taking an organized, systematic approach, supposed solutions were thrown at the problem in an attempt to fix it. Almost always, this is because we don’t completely understand what it is that is happening. Gathering, printing and writing down all the information during the initial check-out may seem like it could take a significant amount of time and effort, especially when gathering it for the first time. After you develop the discipline to do so, it becomes a comfortable process. Having all the necessary information in front of you enables the easy organization and understanding of potential causes. With the correct information you are able to know, and not just assume, keeping you on a focused track to finding out what the problem is, and significantly saving wasted time, money, and effort. This process alleviates mistaken thoughts and helps us remain focused, addressing the problem as a new one, not projecting previous diagnoses onto the vehicle.

To me it is clear: by taking the time to gather a complete and accurate list of information and working through the problem on paper, it will always help you make a more focused and efficient decision.

In-Depth Testing Reveals Obscure Ground Problem

By Chris Adams, Diagnostician

author1Chris Adams started with Certified Transmission in 1986 as an R&R technician, and currently works as our Diagnostic Trainer. His current duties involve training and advising our retail diagnosticians, as well as assisting in the research and development of our remanufactured products. He also holds ASE Master and L1 certifications.

 

 

 

Sometimes despite your best efforts you can still manage to shoot yourself in the foot. The following account is a prime example of this; while this happened on one specific vehicle, it could happen on any number of vehicles where the cause is the same, but could have different end results.

One of our shop locations had a 2011 Jeep Patriot that came in on the back of a tow truck. The customer stated that it started making noise and then quit moving. This one was an easy checkout; the vehicle didn’t move in any direction, had metallic-looking fluid, a horrendous bearing noise, and had a P0777 (secondary pressure control solenoid stuck on) code stored. Even though this one was pretty much a slam dunk in the way of diagnosis, we still needed to go through our complete evaluation procedure.

The Jeep is equipped with the 2.4L engine backed up by a JF011E CVT transaxle (the Nissan version is the RE0F10A). Since we started remanufacturing the CVT applications these transmissions have been selling really well. The Service Advisor contacted the customer and let them know the results of our evaluation, and how much the completed job would cost. The customer agreed to the repairs and the remanufactured unit was installed. After a R&R is completed, the job then gets handed off to me. One of the things we do in our evaluation is check to make sure the software calibration is current, and this one was not. There were updates to both the ECM and the TCM.

Each of our locations have a subscription to the Tech Authority website that we use for service information and programming, and we use the FCA J2534 software and a Snap-On pass-thru pro +4 to complete the required reprogramming for these applications. The next thing that needs to be done on these units (can be done before or after programming) is to initialize the CVT transmission with a capable scan tool, and in this case we use the Snap-On Zeus workstation. After the transmission is installed the TCM will set a P167A (calibration mismatch) DTC. This procedure only takes a couple minutes from start to finish, and then you can either clear the DTC or after a couple ignition cycles the code will go away on its own.

Now we were ready for the road test. It didn’t take long to notice that we still had a problem as the vehicle had a really bad rolling surge. I immediately returned to the shop so I could check the fluid level, hoping that maybe we didn’t get the fluid level to full, but this was not the case; the fluid was at the correct level. I took the scan tool and set up a custom data list of all the PIDS I thought I needed to look at, and went for another road test. This time I had an associate drive the vehicle so I could watch the scan data, and the vehicle was still exhibiting the rolling surge. Watching the scan data, I could not see anything that was causing it. I could see the results of the surge, and I could see what I thought was causing the CVT to surge, but I just could not comprehend why.

I could see that the PL solenoid monitored current and output current were going right along with the engine RPM and the primary pulley RPM, but was this the cause of the surge, or a result? I still did not see anything that would cause this, so I scrapped the custom data list and just brought up the entire PID list for the TCM instead. While the data updates at a slower rate when you are looking at so much data simultaneously, I had to do something different.
This time I conducted the road test without the aid of an associate and recorded a movie as the issue was happening. I reviewed the data when I got back to the shop. This time I could see a potential cause; the “unswitched battery voltage” was erratic and varying in output at right around .4 volts. (figure 1)

1811a

Figure 1

Next, I needed to see why this is happening and if this is the cause of the surge. Another part of our evaluation includes a battery and charging system test, and we use a Midtronics ESP-1000 analyzer which has been proven to work very well and even does a pretty accurate ripple test. I re-ran the test and everything passed (figure 2). Not wanting to leave anything to chance, I hooked up the scope and looked at AC voltage, and even with that the ripple was at an acceptable level. The thing that did catch my attention was that the zero point seemed to be in somewhat of a wave. At this point I was checking voltage drop on the ground side. When I removed the air intake tube so I could get to the main battery ground cable on the starter bolt, I saw this: (figure 3)

1811b

Figure 2

1811c

Figure 3

The technician attached the main battery ground up to the throttle body bracket that is mounted with rubber bushings on each side, rather than to the starter bolt right next to it. We moved the cable over to its proper location and the voltage drop looked good everywhere I had checked, so now it was time for another road test.

I could immediately tell that the problem was fixed, so I took another recording so I could use this case as a training tool with our technicians. (figure 4)

1811d

Figure 4

The PL solenoid current was smooth as was the engine and primary pulley speed. There were still some unswitched battery voltage irregularities but they were not affecting the operation of the transmission. I am suspecting that there might have still been some issue with the alternator function, but I have not had another one of the same vehicle that I could compare it to. I think we have all had our tails kicked by a bad ground, but this one had so much of a mechanical feeling effect of the operation of the unit that it really surprised me.

My initial reaction to this when I was driving it was that I was going to condemn the remanufactured unit, as I think it would have been a fairly easy call to make. As the manufacturers are adding more complexity to the electronic controls inside the transmission in the way of more solenoids and even pumps for the stop/start systems, the electrical current required to run the transmission keeps increasing. This in turn will require the entire electrical system to be in perfect working order to keep everything working as it was designed.