What Were They Thinking???

By Randall Peterson

All too often, I shake my head and wonder, “What were they thinking?” Case in point is a 1992 Ford Bronco, 5.8L, with an E4OD transmission. The vehicle came to our shop with shifting issues. The owner said he was driving along and all of a sudden it shifted down and then slammed back into gear. A short time later, it shifted down again but this time it would not up shift. He thought it was stuck in low, although it did not act up on the way to our shop that morning. The owner had recently purchased this vehicle with some known issues. There was a rear ABS lamp on and NO Check Engine Lamp on.


This Bronco had been to another shop with the previous owner. We were able to acquire copies of the repair orders. Six months prior the original owner complained of slipping, hard to get into gear, play in the shifter and shifting hard from first to second gear. At that time the shop replaced the transmission range switch (MLPS) and updated the connector. About 4 months later the original owner took the vehicle back to the repairing shop with the complaint of slipping very bad on take off. The shop performed a pan inspection and found minimal debris in pan or filter. The shop serviced the transmission and did something that left me thinking “how did they do that?”

The notes on the repair order stated “We set the computer where the system would erase its memory on key cycles. Vehicle may need a computer replaced.”

Now that it’s here I need to figure out not only what’s going on with the transmission but I need to figure out what was done to the computer. I started with printing out a schematic and a computer pin chart. I reached deep into the depths of my tool box and got out a long lost tool, my 60 pin breakout box.


Since there is virtually no data from the scan tool I wanted to see what the computer was commanding. Were the random shift problems commanded or was it something from inside the transmission? As I was accessing the computer I noticed someone had been here before. There was a wire splice, with a yellow wire spliced to a red wire. Once I removed the computer connector I could identify the locations of the wires in question.

Wire diagram

The Yellow wire was from pin #1, Keep Alive Power, and the Red wire, pin #37, Vehicle Power, which is Ignition voltage. At first I was thinking, “what is going on here?” Then it all became clear: this is how they made the computer lose its memory every time the key was cycled. All of us in the shop were scratching our heads and asking ourselves, “Why would you go to that much trouble to kill the keep-alive memory but not figure out the problem and fix it?” I put the wires back to their respective locations and hooked up the breakout box. I checked the powers and grounds first. When that all was correct I hooked up another seldom used tool, my LED box. I wanted to monitor the shift solenoids to see what they were doing during the malfunction. I also did a brief scan of the pressure control solenoid while I was there. It looked proper.

Fancy LED box

During the road test, the transmission was working very well, shifts were smooth, timing was correct and I was thinking, “could the rewire be all that was wrong?” About 2 blocks from the shop, quite suddenly, it down shifted, then up shifted, and back and forth a couple times. I was watching the LEDs and the transmission was commanded to shift this way. It then shifted to first gear and would not up shift. When I pulled into the shop I grabbed the scan tool and checked for codes. I found P0634 stored in the continuous memory codes. These symptoms would be consistent to a faulty MLP sensor. Knowing the MLP was replaced several months ago I was going to have to inspect all the aspects of the MLP circuit.

connector pushed out pins


connector bad wires

I inspected the sensor and unplugged it. That is when I saw three of the pins backed out of the connector. I also took note the wire’s insulation was bad and there were bare wires exposed on all of them. I opted to replace the pigtail harness. I’m sure this was the big  problem and was likely the issue when the computer was rewired. I replaced the pigtail, road tested the Bronco and then rechecked the codes. It drove great; the shifts were very nice, TCC worked. Just one problem, the P0634 was stored in continuous memory. Maybe it did need a computer. Before I could confidently recommend that I better make sure everything I did was correct. As I was retracing my steps my buddy said “are you sure the wires were in the right spot on the MLP?” I told him I put it back together exactly how it was. That wasn’t a good answer. I pulled out some old information that described the connector, the wire colors, circuits and positions. Sure enough, there were two wires in the wrong locations. I made the correction, drove the Bronco and now there were no more codes stored and the Rear ABS lamp was no longer on.



connector wrong wire location

This is my take on the situation, first of all I’m sure the MLP was at fault and causing the shifting issues when the vehicle was looked at last time but when the code would not clear and the vehicle didn’t always shift correct it was concluded it must be a computer at fault. I see this scenario more and more and I ask myself “What were they thinking?” Or maybe better yet “Why weren’t they thinking?” There have been many times I made a diagnosis and performed the repairs and did not get the right results. Then I have to go back retrace my steps and see if I missed something, did something wrong or if I misdiagnosed it. I don’t like it when that happens but its all part of the game.

Less Time Spent Diagnosing

Written by Richard Middleton

Recently, we sold a 4L60E to a neighboring shop. They installed it, but then they brought it back to us due to a P0753 shift solenoid A code. It would reoccur consistently and almost immediately when driving. However, the transmission would NOT go to failsafe mode (this is a key point).

I did a quick resistance check on the solenoid and it was fine, so I thought maybe it was a connection issue.  I wanted to do some amp tests with a scope and amp clamp but I found it difficult to get to the circuit without opening the harness (which was far too much work).  So, I just did the amp test at the transmission with a test harness plugged in. It was fine at 0.4 amps on the A solenoid.  I checked the B solenoid for comparison and it was 0.4 also.  This test is dandy but doesn’t show you a problem with the wiring, connections or computer.

The best test would have been to drive it, measuring amps on the A solenoid wire between the solenoid and the computer, but since I couldn’t find easy access to the harness, I decided against it.

It is possible to jumper across the fuse that powers the solenoid (above) with a wire and put your amp clamp around that; unfortunately, there are other devices on the fuse that activate while driving. They draw extra current and create inaccurate readings. But, if you do the readings in the bay using bi-directional controls with the scan tool, the other stuff on the fuse isn’t active.  This is the way I chose to do it.

I measured amperage at the fuse while turning the solenoid on using bi-directional controls in the scan tool (above).  This loads the entire solenoid circuit just as the computer does running down the road.  This test was showing 0.4 amps on both solenoids, so I was pretty sure it was a computer problem.   I called up the shop that installed the transmission and they said, “yes, the code was there before”.  This would have been nice to know upfront, but ok…

At this point, I knew the computer was capable of making correct amps and the solenoid, wiring and connections were all fine. The code was triggering but without tripping the failsafe.  It was looking like a bad computer, probably in the section that makes the decision whether or not to trigger the code.  Usually a computer failure that creates a solenoid code would be in the amp driver.  But since this transmission continued to work even after the code triggered and the computer could flow correct amperage in the bi-directional test, this makes it a logical decision to try a complete computer replacement.

After installing a new computer, quickly reflashing the system and completing a not-so-quick 30 minute anti-theft relearn, the problem was fixed.  So, with very little time invested in the diagnosis this car was fixed.  I spent more time thinking about it, worrying about misdiagnosis than actually testing it.

Explorer In A Bind

Written by Chris Adams, Lead Diagnostician

We recently had a 2002 Ford Explorer come into our shop with a shifting complaint. The customer had noticed that it slipped or felt bumpy when under a fairly hard acceleration.

Our initial inspection consists of a road test to verify customer concern, computer scan for trouble codes and a visual inspection. On the road test, I felt what the customer was describing; it actually felt kind of like an abrupt engine misfire, something like you would feel with a manual transmission car or a misfire when TCC was applied.

It only seemed to happen at moderate to heavy acceleration between 15 to 40 mph and was a very quick binding sensation when it happened. Upon returning to the shop, the first thing I noticed was the two new tires on the rear of the vehicle. They were a different brand than those on the front. I thought to myself, “Hey, I got this one.” I grabbed my trusty tire stagger gauge measured all 4 tires; shockingly, they were all almost the same exact circumference, even closer than most matching tires that have some miles on them.

Next step was to check for trouble codes. Our scan tool retrieves codes from all modules in one step; as it turned out, the vehicle had no stored codes in the PCM, ABS or 4×4 module. At this point I set up the scan tool to look at the front and rear shaft sensors and the clutch duty cycle. I went for another drive, monitoring the clutch PWM. It was definitely the electromagnetic clutch that was causing the issue, because the PWM % was not steady. I was seeing it randomly drop out or coming on at the times you would feel the bind up. Compared to the readings on the speed sensors on the scan tool, they were a mirror image of each other. I thought this was odd with the way the t-case was acting, so I printed a wire diagram and hooked the scope up to the speed sensor signal wires. At this point I was convinced it was a speed sensor issue and the scan tool was just not fast enough to see the problem. I got the scope set up and went for another drive. As I watched the scope pattern while the problem was occurring I was amazed again, as there was a clean signal with no dropouts. “How could this be,” I thought; Trouble was, I was still fixated on it being a speed sensor problem.

Back at the shop, I got on the computer to looked up service bulletins on Alldata. Lo and behold, I found the following:


2002-2003 Explorer

some 2002-2003 Explorer 4X4 vehicles without AdvanceTrac (Interactive Vehicle Dynamics – IVD) equipped with an automatic transmission may exhibit a shudder in 2nd and 3rd gear on acceleration. This condition may be more pronounced when the vehicle is under load.

Replace the 4X4 control module following the procedure in Workshop Manual Section 308-07A. Refer to the Part Application Table for the correct part number to install.

The bulletin fit the complaint as far as when the problem occurred but I didn’t think it felt like a shudder. Not sure where to go with it next, I did a voltage drop test on the ground side of the system. The worst ground I could find was the 4×4 module ground in the passenger-side kick panel, so I went ahead and cleaned all the body grounds; Still no change in operation.

I decided to pull the trigger and purchased a new module. I got it installed and drove the vehicle the same as in the first road test. Even with several hard accelerations from a stop I couldn’t duplicate the problem, so the customer concern was finally fixed!

However, as I was driving back to the shop I felt another issue, which felt more like a shuddering sensation. It showed up more with light acceleration, so I set up the graphs on the scan tool again and this is what I saw:

Did the new module cause this issue or did I just not feel it before? I plugged in the original module, and the first problem came back, but I could still feel this other issue.

At this point I had already checked the speed sensors and scan tool readings. The wiring diagram I was using showed a wire from the PCM to the 4×4 module which was not really marked. I figured it was the TPS input but when I hooked up a voltmeter to the wire at the 4×4 module it did not look like a typical TPS reading. I dug around a bit and found this in the Description and Operation: “The PCM converts the TPS signal to a pulse width modulated signal, and sends it to the 4×4 electronic module to control and adjust the transfer case clutch duty cycle.”

That made a little more sense, so I once again set up the scope to look at this signal.

The top image above shows the duty cycle at a steady throttle, and the bottom one shows a split second where the duty cycle dropped to what you would see at idle. This is what was causing the erratic 4×4 clutch PWM readings in Figure 2 and causing the shuddering sensation.

Installing a new TPS took care of this issue and it was finally smooth sailing for this problematic Ford Explorer.

Included in the Quote

Written by Jody Carnahan

Previously, fellow technician Jim Stokes provided some insight on problems that can occur both during and after a transmission installation. In this article, I would like to focus on some install issues that you should be aware of prior to selling a transmission repair. They involve additional work that may need to be done after the transmission has been repaired, and possibly requiring a sublet to another shop, or even taking it to the OE dealer.

As most people in our industry already know, the vehicles that are visiting our shops today are very complex. They are equipped with many computer controls that require multiple control units for each specific system within the vehicle. Prior to quoting or making a sale on an overhaul or a remanufactured transmission, the shop owner and/or service writer needs to know what additional work may be required to complete the job.

A full understanding of the vehicle’s requirements for the repair must be considered.  Most of the modern vehicles we are working on will require some type of relearn or reset procedure after the transmission has been repaired or replaced. In addition, some vehicles will require PCM or TCM reprogramming before any relearn or resets can be performed.  This can be true even for minor repairs that don’t involve removing the transmission from the vehicle, such as replacing a valve body or solenoid.

I know that relearns and resets are not new to most shops, and some already have the equipment to perform reflash and reprogramming operations. Unfortunately, doing it on some Asian and European vehicles can be a challenge, as most of these vehicles require a dedicated OE scan tool or software to perform the procedure. I have had many shops tell me that they have worked on several European vehicles and have never had to perform a relearn or reset after the repair was made. I’m not sure if they just got lucky, or was it because of the how the previous unit failed.

Let’s look at an example of what I’ve discussed. Let’s say that you are working on a 2001 Volvo V70 XC AWD, with an AW55-50SN transmission, and the vehicle was towed in because it quit moving suddenly. It is discovered that the transmission had a problem in the final drive area, but no other issues were found.  All of the clutches were like new, and there was no obvious wear evident in the valve body, etc. That being said, the transmission was probably operating normally just before the final drive component failed.

In this particular case, the computer was not attempting to adapt and ramp up pressure for a slipping clutch, etc. This would likely be one of those cases that may road test just perfectly immediately after repair or replacement, even though an adaptive reset wasn’t performed.

Let’s use the same vehicle in a new example.  Now the complaint is reported that the transmission is slipping in 3rd gear, spins up, but is shifting okay. The customer has advised you that it has been functioning in this manner for an extended period of time. When this unit is disassembled, it is found to have burnt clutches, worn valves in the valve body, and the solenoids don’t function properly.

After the repair on this unit is made, I can just about guarantee that you will not merely be able to test drive it (without performing shift adapts), then send it down the road. This is a case in which I usually get the tech call with the common complaint of banging on the 2-3 shift, and harsh downshift clunk when coming to a stop.  By now you probably know where I’m going with this, because shift adapts need to be reset and the TCM needs to be put into what Volvo calls, “Adaptive Control Mode”.  Some early Volvos (2001-2002 models) will require software updates to get them into adaptive control mode. The kicker here is that your latest, greatest, aftermarket scan tool will not perform this function correctly. That’s right: it’s now time to visit your local dealer for help. All too often, the closest dealer is 100 miles away, and the trip and dealer charges will cost you.

I’m not going to single out Volvo since most of the other car makers (whether they be European or Asian) will require some type of adaptive relearn, or TCM initialization, to make the transmission perform properly. Nissan vehicles require a TCM initialization, and in most cases can only be performed with the Nissan Consult II, or III. This is the same for Volkswagen vehicles which need the TCM set back to “basic” settings using VAG software, or equivalent, all of which may require you to take it back to the dealer for these services.

One more note regarding the TCM with regard to Volkswagen. There is a Volkswagen TSB that most shops do not know about.  It involves certain models with the 09A and 09G transmission. A certain percentage of these vehicles will require an updated TCM when the transmission is replaced. For your reference, it is bulletin TT 37-06-06 which states when replacing one of these transmissions (09A or 09G) you must replace the TCM at the same time. To find out if the vehicle you are working on is affected, you will need to call your local Volkswagen parts dept, give them the complete VIN, and have them check to see if a TCM is needed when replacing the transmission. This would be another expense that you will not want to explain to your customer, “after the fact”.

I hope this info has given you some insight on vehicles that will likely require additional work after a transmission repair has been performed. As I stated earlier, you will need to know exactly what you are up against, prior to quoting a sale on one of these jobs.

Why Should I Pay For Diagnosis?

Written by Randy Peterson – Diagnostician

This month’s star is a 2003 Lincoln LS, packing a 3.9L V8 and a 5R55S.

This vehicle came into our shop with a laundry list of codes, no power, and it couldn’t shift. I scanned for codes and found P0715, 717, 718, 731, 732, 733, 734, 745, and P2106. As you can see it, had turbine speed sensor codes, gear ratio codes, pressure control fault and a forced limited power from the TAC.

My first thought was that the turbine speed sensor had failed, causing the other codes. I looked at the data on the scan tool. There was a signal from the turbine speed sensor but it was very erratic. I recommended we do further testing on the system to pinpoint the fault but the vehicle owner wanted to replace the turbine sensor. Reluctantly, we did, but the problem was still present. The vehicle owner didn’t want to go any further at this time.

A month later our customer brought their Lincoln LS back and said it was still acting up and wanted the advanced diagnostics performed. I scanned the computer again and found the same codes plus a new one: P1397 (system voltage out of range). When I raised the hood to check the engine oil level, I found the TAC assembly had been replaced. I asked who replaced it and was told there was a code for it so the owner of the vehicle bought one and put it on. I wasn’t surprised, as that’s the same mentality they had the first time we looked at the vehicle.

First things first I did was a battery and charging system analysis. This should be the first step in any analysis, but especially with the system voltage out of range code. Everything but the battery tested OK, so we replaced it with a new one.

Now that we had the go ahead to dig deeper, we had a fighting chance to figure this out. I printed off a wiring schematic and studied it briefly. The transmission uses three speed sensors: turbine speed, intermediate shaft speed, and output shaft speed. The code reference is for the turbine speed sensor and says nothing about the intermediate shaft speed sensor until you get into the pinpoint test. The pinpoint test then instructs on how to test each of the three components. Now I’m thinking since there’s no specific code for the intermediate shaft speed sensor, could this be our culprit, as it shares the turbine sensor code? I accessed the wire harness at the power train control module and probed the turbine speed sensor wires and the intermediate shaft speed sensor wires at the PCM. We ran the car through the gears.

There is no data PID for the intermediate shaft on my scan tool.

 The turbine sensor (green trace) had a good wave pattern and the intermediate shaft had a flat line (yellow trace).


 At the same time the graphing scan data showed an erratic turbine speed sensor. I wondered if a failed intermediate shaft sensor could be causing an erratic reading on the scanner. I would need to replace the intermediate shaft sensor to find out. We replaced it, and with all the probes still connected I started the engine and watched the pattern. The intermediate shaft was now working.


The yellow trace is the turbine speed sensor and the green trace is the intermediate shaft sensor. Both had good patterns. Next, I checked the scan tool to see if the turbine sensor reading had cleaned up.

It hadn’t.  I played around with the engine RPM to see what would happen. If I kept it below 1230rpm the reading on the scan tool was a clean line. Once it went over that threshold, the reading became erratic. We were getting a good signal to the computer, but a bad signal on the scan tool. We recommended a replacement PCM, but the customer declined the repairs because they had no more money to put into the vehicle. So at this point, the vehicle still has an issue.

I’m thinking to myself had the owner not been so hasty to replace the TAC assembly and allowed us to diagnose the problem initially, there may had been enough money in the kitty to repair the vehicle.

Maybe we’ll see it back in a month.

Top 10 Install Problems – Part 2

Written by Jim Stokes – Warranty Technician

Jim has held many titles in his 12 years at Certified Transmission.  He’s been a service writer, diagnostician, helped run Certified shops, and has now been a part of the warranty team for almost 10 years.

Our company sells hundreds of wholesale carry-out units, as well as performing thousands of in-house installations.  Our talented team of technical advisers provides guidance for both types of installs, and we’ve found a number of common issues that installers face on a daily basis. In Part 2 of this series, we will be exploring the remaining 6 top install problems we encounter.

5.  Power and Grounds

The GM trucks with 4L60E and 4L80E transmissions seem to frequently have power supply issues.  Defective ignition switches are the normal cause of the problem, and we have seen a few vehicles with aftermarket products incorrectly wired into the power supply circuit for the transmission.  We suspect that many transmissions have been misdiagnosed and sold for symptoms created by the bad ignition switches, as we have had several calls immediately after install reporting a concern identical to the unit that was just replaced.  GM TSB 01-07-30-002A goes back to 1997, but we have seen the problem in 1994 models. The TSB has been updated to 01-07-30-002E to 2005 models, so it affects a lot of vehicles on the road today.

We have had several calls on Toyota vehicles that won’t start, won’t shift, and wrong gear starts right after installation of a replacement transmission.  A poor ground connection at the transmission case is often the cause, and sometimes at the battery ground also.  We have seen similar concerns in other vehicle makes, also.  The most prone vehicles are power-side controlled systems, where the PCM/TCM sends voltage to the solenoid being controlled and the solenoids are permanently grounded to the valve body.  With this type of control system, ground cables are connected directly to the transmission case.  These ground cable connections are often used for PCM/TCM return signals, so they must be clean and secure.

All power and ground connections must be clean and free of excessive resistance.  Since the battery is usually disconnected when installing a unit, clean the connections before connecting them.

6.  Engine Sensors

Engine sensors have a big impact on transmission performance.  MAF, TPS, oxygen sensors, knock sensors, and coolant sensors are all potential trouble for the transmission’s correct operation.

We had a 2002 Buick Century with a freshly-installed, remanufactured 4T65E.  It had slow, soft upshifts, and if heavy throttle was applied, it would slip.  It wasn’t driven long enough to set GRE codes, but it would have set codes if driven for any amount of distance.  The installer was an industry veteran at a quality shop, so I sent him a replacement unit based on his own diagnosis.  After installing the replacement unit, it had the same problems as the unit just removed. He installed a pressure gauge and found that the unit had no line rise with increased engine load.  He connected a scanner and manually controlled the PC solenoid, and the pressures stayed in spec with each increased pressure command.  After replacing the MAF sensor, the unit worked as designed.  The engine did not have any drivability concerns, and no DTC’s set.  Because the MAF was bad, incorrect load calculations from the PCM were causing a slip condition.

Engine coolant temperature sensors can cause 518/618 units to go in and out of lock-up if they fluctuate around 160 degrees, where TCC engagement is allowed on.  The same vehicles can have a no upshift complaint, or incorrect gear starts if the oxygen sensor ground is lost or contaminated.  The governor solenoid and the O2 sensors share grounds.

We recently had a 2000 Lexus RX300 that didn’t have 4th gear immediately after install.  After hours of unsuccessful diagnosis, it was discovered that the exhaust manifold was leaking near a knock sensor, and caused the PCM to inhibit the shift.  These same vehicles will not shift to 4th gear if a knock sensor code is present.

Improper TPS signals will affect multiple vehicles causing them to have soft or harsh upshifts, engagements, early shifts, slipping lock-up clutches, and shuddering.

7.  Performance modifications

Applying modifications that result in a large increase to engine performance, but without modifying the transmission, is nearly always going to end up badly.  The easily-added performance chip, download, or module can add up to 100 or more HP and torque to an engine, but the factory has the original programming tuned to protect the OE transmission from damage.  When that protection is removed, it usually ends badly for a stock-level transmission, but if the repairs are done correctly with the knowledge of the modification, it can be very profitable.  Be careful of these vehicles because without that knowledge it can be a costly mistake for the repair shop.

8.  Converter bolts

Proper installation and usage of converter bolts is critical to avoiding a major failure.  We have had units returned with converter dimpling problems from 4L60E units, all Chrysler units, Toyota units, KM models, and most recently a rash of AW55-51SN units in both Nissan and Volvo applications.  Just the slightest dimple in the converter cover will eventually cause a clutch failure to occur. We have seen it happen anywhere from 10 to 7000 miles of use and the end results are always the same.  Verify that the correct, OE-spec bolts are used in all mounting holes since it only takes one incorrect bolt to cause failure. Also, use a torque wrench when tightening the converter bolts.

9.  Seals

A remanufactured or rebuilt unit is going to have all new seals installed, preferably with the best quality available.  All seals should be installed with alignment tools that keep them straight and in alignment, and if it is a metal-clad seal the metal portion should be sealed to the case and the proper tool that sets them to the correct depth.  A word of caution: inspect yokes and axles carefully for damage and wear before installing them, and be careful not to bang into them when installing a unit.

10.  Cooler cleaning and contamination

Proper cooler cleaning is a problem for the remanufacturing industry.  Not so much with professional transmission shop installations, but more so with the general repair shops that do not have access to the proper equipment needed for modern vehicle cooler flushing.

Another problem we see often is fluid contamination originating from dirty coolers, and intrusion through the vents.  Ford has issued TSB 05-23-7 for 1999-2003 Windstar, and 2004-2006 Freestar vehicles for water getting into the units through the vent.  Water is routed from the cowl under the windshield and ends up in the transmission vent.  The cowl requires modification to correct the condition, and I would also suggest adding a hose to the vent to relocate it and have it face downward, if possible.  We have seen many units damaged from water intrusion both in cores, and returned failed units.

Top 10 Install Problems – Part 1

Written by Jim Stokes – Warranty Technician

Jim has held many titles in his 12 years at Certified Transmission.  He’s been a service writer, diagnostician, helped run Certified shops, and has now been a part of the warranty team for almost 10 years.


Our company sells hundreds of wholesale carry-out units, as well as performing thousands of in-house installations.  Our talented team of technical advisers provides guidance for both types of installs, and we’ve found a number of common issues that installers face on a daily basis. In this two-part series, we will be exploring the top 10 install problems we encounter.

1.  Software updates, clearing shift-adapts, and performing relearn procedures

Software Updates

Hands down, updating PCM/TCM software corrects more problems than anything else.  It just makes sense that the OEM software may not operate the transmission as originally intended, and adjustments have to be made to correct problems.  Where it gets tricky is when the factory doesn’t publish an update on a TSB to notify technicians that a change has been made.  For that reason, the latest updates should always be installed when a replacement transmission is being installed.


Shift adapt strategies have been common for well over a decade now.  When a unit is failing, the PCM/TCM will be constantly trying to compensate for the slipping or harsh shifts produced by internal unit failure.  Any time a transmission is rebuilt or replaced, the shift-adapts must be cleared.  A few years ago, disconnecting the battery would clear the shift-adapts in most vehicles, but this is no longer the case.  Often an OE factory scan tool is required.  There are many aftermarket scan tools that have adapt-clearing functions, but the results are not always effective.  Only a factory scan tool can guarantee results every time.

As an example, we had a 2005 Mitsubishi Montero with a fresh reman unit installed that had a 1-2 shift flare and a harsh 2-3 shift.  The installing shop had a new, aftermarket, top-of-the-line scan tool that had a function test for clearing shift adapts.  The tech had performed the shift-adapts clearing procedure prior to calling in the claim.  After attempting a cleaning of the MAF sensor and trying to tweak the TPS adjustment without favorable results, we sent the installer a replacement transmission.  The replacement unit had the exact same shifting problems, so we had the vehicle taken to the Mitsubishi dealer to have the shift-adapts cleared.  After the procedure was performed with OE equipment, the unit worked perfectly.

Relearn Procedures

After the shift-adapts are cleared, some units will function normally right away while others must learn how to shift properly.  Some must also learn how to engage into forward and reverse without excessive bump.  There is a procedure known as “garage shifts” that involves engaging the unit into reverse five times with a 5-second interval, and the same into forward.  In some cases, this is all that’s required.  The upshift relearn is normally performed with 5-10 shift cycles through all gears at 20-25% throttle angle.  Some manufacturers require more complicated procedures, so research may be required for specific vehicles.


2.  Details in set-up procedures

Throttle Cables

Though these units haven’t been in OE production for over a decade, they are still very popular:


There is only one way to properly set up these units to shift correctly (and make them survive): a pressure gauge.  If you call in a claim on one of these units, the first words you will hear from us are, “What is the pressure reading at factory idle speed?”  If you don’t have the answer, we will request a call back with that information.  This is a critical setting for these units and use of a pressure gauge is the only sure way to get it right.

Most other types of units utilizing a throttle cable are much simpler to set up, as they only require synchronized TV movement with the engine throttle.  On the Chrysler RWD vehicles, make sure that there is a return spring on the throttle lever (at the transmission), or you will end up with harsh downshifts.

Range Sensors/MLPS

Ford Explorers equipped with the 5R55W/S transmission seems to have the most claims that are generated due to MLPS problems.  The most common symptom is delayed or no reverse engagement.  In most cases this can be corrected with a simple adjustment of the sensor. Ford specifies a special tool for the adjustment, but some shops aren’t going to have access to one.  One workaround is to monitor PID data on a scanner. Using the scanner, go to “live data” and find the digital signal PID from the sensor; it is four binary digits.  With the shift cable disconnected, shift to neutral at the transmission lever and adjust the switch to a signal of 0110, then shift to REV and look for a signal of 1100, and finally to DRIVE and look for 1111, if you don’t see these number sequences, replace the switch and adjust again.  Shift back to neutral at the transmission and put the column lever in neutral, then adjust the cable so that it lines up exactly with the shift lever.

Honda units have a unique problem with their gear position switches.  Symptoms of problems with the switch can include no reverse, no forward upshifts, or neutralizing when accelerating from a stop.  A common cause of these symptoms is the manual shift shaft getting damaged during the installation.  The shaft is slotted to accommodate the switch actuator notch.  The shaft can get pinched together during installation of the unit, and the switch cannot engage with the pinched slot. The diagram below shows the shaft:



1993-1995 GM trucks with 4L60E/4L80E transmissions

A common problem with these ECMs is high line pressure that generates customer complaints of harsh 1-2 shifts.  Typically, line pressure at factory idle speed will be 110-140 psi, and rise to 160-170 with higher engine RPM.  This is normal pressure that occurs due to higher pump output caused by the increased engine speed.  To diagnose a high line pressure condition, use an amp probe or meter hard-wired into the return circuit of pin D of the case connector at the ECM connector harness.  Compare the actual amp reading to the scanner actual reading.  Typically, if the ECM is faulty, you will see amp meter readings from 0 to 0.3 amps, and scanner command readings of 1.0-1.1 amps.  If the readings don’t match (as per this example), the ECM is the problem.  Lately we have had some late model 1997-2001 vehicles with the same problem, and the diagnosis process is the same.


We had a 2005 Sprinter setting several codes pertaining to GRE, solenoid electrical and performance, and speed sensors that was difficult to diagnose.  We had the shop ohm testing circuits and also load testing them with a headlight.  This went on for about a week and a couple of calls a day without any progress.  I was working on another problem vehicle when I found Wayne Colonna’s article in the 06/07 TD, “Coping with Capillary Action”.  I immediately called the shop and had them remove the TCM from under the seat, and they found that it was full of fluid.  We had them install a new TCM and seal the wire harness with solder, and the unit worked great after the repair.  We still find this to be a continual problem with the Sprinter vehicles.  We have seen TCM replacements also correct problems with GRE codes and no shifts past 2nd gear, though no fluid was found in the TCM.

2000-2004 Jaguar S-type, 2000-2003 Lincoln LS, and Ford Thunderbird

These vehicles can develop a pressure control problem with complaints of harsh engagement, harsh up-shifts from 1st to 2nd, and 3rd to 4th, and harsh 2-1 coast downshifts.  Pressure readings can be in the 170 psi range at factory idle speed.  Idle speed is an important factor, as many of these vehicles have issues with high idle speed due to a faulty throttle body.  Another common cause is a bad PCM.  To diagnose it, the best tool for the job is an amp probe.  If the actual readings measured on pressure control solenoid ‘A’ don’t match the PCM command, the PCM is faulty and will require replacement.  The OE dealers do not usually stock these PCMs, and they are quite expensive.  We have had shops report successful repairs from independent repair facilities that have the ability and equipment to repair the PCMs internally, and reprogram them to work properly.  We don’t have the luxury of this service here in the Midwest, but on the Coasts, there are techs in the business.


RAV4, RX300 series, Corolla, Matrix, and Pontiac Vibe are having PCM-induced transmission problems, primarily around 1999 to 2004 m/y vehicles.  The most common issues are seen with the RAV4 vehicles, and Toyota has issued T-SB-0156-10 that addresses the problem.  There is a revised PCM part number to resolve the shifting issues.  The primary concerns involve the 2-3 shift with a bind-up, or a spin-up with a double-bump.  Lately we have seen several Lexus RX300 series vehicles with this same concern, but there aren’t any published technical information documents from Lexus that address it.   It doesn’t take very many shift cycles to damage the direct clutch in the transmission, and eventually the clutch fails.  Replacing the PCM seems to be the answer, similar to the Toyota repair.


4. Electrical connectors

Vehicle harness connectors can have multiple problems: little to massive amounts of corrosion, loose pin fitment and fretting, broken lock tabs, and seized connectors that won’t unplug from the transmission connector.

E4OD/4R100 units seem to have the most connector problems, and with the exception of seizure, they seem to have all of the other concerns.  The lock tab is very easy to break and causes poor electrical contact, DTCs, and overall performance problems.  It isn’t uncommon to get a call with an electrical circuit code.  I will usually send a replacement solenoid pack when this happens to eliminate the transmission as a cause first.  Often times I get another call after the replacement solenoid pack is installed with the same code, or a different circuit code.  After some coaxing the customer will finally admit that the lock tab is broken from the harness.  I see a lot of corrosion from these connectors also and it seems to be worse on the east coast, but recently had a customer in Iowa that had returned the “defective” solenoid pack and connector. It was so badly corroded that the pins in the solenoid pack were eaten away to nothing in a short, 4-week time frame.

Ford 5R55S-W-N units use a bolt-in connector that is very difficult to remove from the solenoid pack at times.  We have had some shops successfully remove the connector with the help of a heat gun.  Last I checked there weren’t any replacement connectors readily available in the aftermarket, and use of a Ford part requires replacement of the entire harness, as the connector is included with it.

Cross-connecting shift solenoids and sensors has been an ongoing issue for a while now, but never seems to be getting any better.  It could be assumed that, because of the cost-savings of using the same connectors in multiple locations, the OE chooses to manufacture some cars in this fashion.  I first ran into the problem about 16 years ago. I had replaced the engine harness and several sensors on a 1996 Accord that had an under hood fire.  The engine would start but wouldn’t idle, or run even with the throttle applied.  It turns out that I had the MAP sensor and the TPS cross connected.  Hondas still have this problem today, because many of the shift solenoids and sensors use the same connector, as do the pressure switches.  If they have the same pin count in the connector, it will plug into the wrong component and cause issues.

Mitsubishi and Hyundai vehicles also have the same problem, usually with (but not restricted to) the pulse generators.  Mixing up these sensors can have multiple issues, including no reverse, wrong gear starts, and no upshifts.  Color matching the harness connectors will often find the problem quickly, but not always.

Just recently we had a 2008 Mazda Tribute that had a long, delayed reverse engagement, and was hunting in and out of 2nd and 3rd gear.  The vehicle had been driven only 5 miles after installing the transmission.  We were about to ask him to send the unit back to us, but then the customer revealed that the speedometer was reading much slower than it used to.  It turned out that he had the connectors crossed for the input and output speed sensors.  After that was corrected, the unit worked fine.

Having a component locator available to view along with a good wiring diagram will usually help sort this type of problem out in a short amount of time.

Next month, in Part 2, we’ll cover 5 through 10 of the Top 10 Install Problems.

The Tale of Two Hyundais

Written by Chris Adams, Diagnostician


We recently received a call from one of our wholesale customers that had purchased a carry out transmission for a 2005 Hyundai Santa Fe. The vehicle had been out for a few months and was returned to the installer with a complaint of slipping shifts. Our customer had driven the vehicle and verified the complaint, removed the transmission and called us to send a replacement. With the transmission already removed, there wasn’t much we could check, so we sent out a replacement.

The following day, we received a phone call from the installer who informed us that the replacement transmission was doing the same thing as the old one. At this point, we told them that we had to get the vehicle to our store to figure out what was going on.

When I first test drove the vehicle it flared badly on the 2-3, 3-4, 4-5 and had harsh downshifts. It felt like it just hadn’t completed its relearn procedure, and after driving several miles, it did start shifting better. I wanted to make sure that it wasn’t a heat-related issue, so I disconnected the battery cables and connected the positive and negative cables together for several minutes to clear the adaptive memory.

In the first part of the second test drive, the transmission was shifting very poorly just as when I first drove the vehicle. It took nearly 30 minutes of driving to get all of the shift adapts relearned, and the transmission was working properly again.

When we were finished and the installing shop came out to pick up the Hyundai, it had sat at our shop over the weekend. This leads us to why the Hyundai had come back in the first place. We tried to start it, but the battery was completely dead. Turns out that the combination of a bad battery and a GPS left on under the seat had drained it.

The customer had failed to tell the installer that the vehicle had to be jump-started right before the problem occurred. We installed a new battery and went through the 30 minute test drive/relearn procedure again and all was returned to normal.

Two weeks later, another 2005 Hyundai made it into our shop with a  slipping in 3rd-4th gear, burnt fluid, and gear ratio error codes. We installed one of our remanufactured transmissions and on the initial test drive it had very harsh upshifts into 3rd and 4th. We had the battery disconnected during the R&R but we did have a battery memory saver installed to save the presets. I figured that the transmission adapts had not cleared and immediately disconnected the battery cables and tied them together for several minutes. The vehicle still shifted harsh and did not seem to come out of it, so I repeated this procedure again and left it for almost an hour with the same result.

After some additional research, I found that there were four TSBs for this vehicle. All of them were related to the relearning and resetting of transmission adapts. I had read the first two of them when the first Hyundai had come in and since both were almost identical, I did not bother reading the others. That was my mistake. The 4th TSB had the following statement:

The transaxle controller adaptive values are download to the controller EPROM when the ignition key is turned “OFF”, then upload when the ignition key is turned “ON”. For this reason, the adaptive values cannot be reset by disconnecting the battery cable.

The Hi-Scan Pro must be used as shown to reset the adaptive values in order to provide smooth shifts after the following repairs:

* Replace automatic transaxle.

* Reprogram transaxle control module (TCM).

This particular Hyundai was built after 08/01/2004 (see below), which explains why the adapts would not clear with a battery disconnect. Since we did not have a scan tool with the abilities to reset the adapts, we had to take it to a dealer to have the reset procedure done. After that, a lengthy test drive proved everything was operating perfectly once again.


Old Guy, Old Problem…..Young Guy, Old Problem

Written by Dave Miles – Director of Engineering

As the Director of Engineering at Certified Transmission, I seldom get to contribute to a shop related article. Most of the time I’m relegated to calling our store guys and asking them if they have any articles that they want to submit or playing editor to the ones that they send in.

But this month, I have something to write about. After all, I’m the Old Guy.

Having been in this game for over thirty years, I still remember what an Old Guy OEM engineer told me when I was first hired on with the OEM as a manufacturing engineer at the ripe old age of 22. He said, “There are no new problems; we just keep solving the same ones over and over again.”

For the most part, I have found through the years that the Old Guy was right. What goes around comes around and if we ever think that we are smarter than those “Old Guys”, that just adds to the proof that we are not.

Thus is the case with the 2000 Crown Vic that showed up at one of our installers. 190,000 hard miles and needing an exchange unit installed, the Young Guy (tech) quickly pulled the unit and dropped in a fresh 4R70W reman. It all went smoothly until the test drive.

During the drive, the Young Guy (fresh out of trade school with a whole 6 months under the hood) noticed a slight vibration with a bit of unusual harmonics… the old NVH concern. Taking a look at the tires and noticing some slight cupping on the front wheels, he quickly dismissed any driveline related issues and called the customer to come and get his car.

The customer left with the Crown Vic, but quickly returned to the shop and told the shop owner that his car had a vibration, noise and whap… wham noise (harmonics) that was not present when he brought the car in for the transmission replacement.

The shop owner called in the tech and asks him if he had heard the noise, felt the vibration and the whap, wham noise during the test drive. “Of course I did, it’s got some bad tires on it” replied the tech. “If you put some new front tires on, the noise will go away.”

The customer again explained that the noise and vibration was not there when he brought the car into the shop. He was quickly corrected by the tech that it was tire noise and vibration and that maybe he had just gotten used to it over time. Since he had this new transmission, maybe the old tranny noise had just drowned out the other noise. Tech or salesman??? You decide.

Well, you guessed it. The customer was back, but without new tires. This time he was not leaving until the vibration and noise was gone. He was also armed with another piece of information. He just happened to be my uncle (an even older Old Guy) and knew that one of our transmissions had been installed. He called me at home during the weekend to ask me what could be causing the vibration and the noise.

Now remember that this is a 2000 Crown Vic with a 4R70W. In 1998, Ford had a problem with NVH concerns with the 4R70W and decided to do what is known as “Vector Aligning” the drive shaft, output shaft and ring gear. In other words they balanced them as an assembly. They all have to line up. I told my uncle that there should be paint marks on all three pieces and that the marks should all be in-line which each other. If the marks were worn off, just have them rotate the drive shaft and output spline 180 degrees and see if the noise and vibration goes away.

He explained this to the Young Tech. The tech proceeded to tell him that he was the customer and that if that’s what he wanted him to do, he would, but it would NOT fix the problem. In his vast technical experience, it was bad tires.

The Young Technician did as asked, and rotated the output shaft in the ring gear. Sure enough, all of the noise and vibration (NVH issues) disappeared. He sheepishly apologized to my uncle and explained that the Old Guy who trained him had always told him to mark all of the driveline parts before he disassembled them, but that he had thought that doing it was just a waste of time. The Young Guy had just learned an Old Guy lesson the hard way.

Chalk one up for the Old Guys.

Quit Dimpling Those Converters

Written by Steve Logeman – Technical Director

This all started with me looking at multiple converter failures. They were due to the converter bolts damaging the backs on Toyota A245E/A246E transmissions that attach to the 1.8L engine. Oddly, we also see this in other Toyota applications, maybe more so than other vehicle manufactures.

My intentions were to order some factory bolts to get the proper dimensions and possibly send these reman units out with new bolts, be they either O.E. or an economical replacement. I was hoping this would eliminate any confusion for the R & R tech on which bolts to use, therefore eliminating unwanted warranties. What I found was very humbling. I have worked on my share of Toyotas over the years and consider myself a well-rounded transmission technician; that’s why I was pretty shocked to find out that this transmission/engine combination has two unique torque converter bolts. Five of the six are part #90119-08498 and one is part #90109-08113.

At this point, I ordered some bolts to see what the difference is between the two. I also asked my local dealer to give me a list of vehicle applications that these bolts went in. No surprise, but these bolts fit a wide range of vehicles going back to 1985. Now I am really curious and racking my brain for any memory of the bolts being different.

When the bolts arrived, I could see bolt #90109-08113 had a shoulder; not a very noticeable one, but enough to ensure that if you install this bolt first, it will center the flywheel to the converter. This allows the other 5 bolts (#90119-08498) to be installed without misalignment.

They are also different colors. As I was waiting for them to arrive, I had our purchasing manager and the dealer look at other Toyota transmissions. We discovered that they also had one bolt that was different. I had other bolts ordered for other applications and the one unique bolt was shouldered also and a different color.

You can see how this explains all kinds of scenarios where an R & R technician may resort to searching though his box (or five gallon bolt bucket!) for a bolt to screw into the converter.

When you take all six bolts out and throw them in with the rest of the R & R bolts, you don’t really pay that much attention to what color they all are; on top of that, they’re probably covered with oil, dirt and dust. So now you are reassembling the unit and you only have five converter bolts of the same color… or do you have all six the same color? Maybe one just came from somewhere else… dust cover, heat shield, five gallon bucket? You follow where I’m going with this?

While talking with my one of my co-workers about these bolts and my thoughts of writing an article about them, it must have triggered the Rolodex in his head. He looked at me and said, “I think there’s a bulletin about that somewhere!” Sure enough, after digging though his old Toyota folder, he pulls out Toyota tech bulletin #016 dating back to September of 1989.


These larger bolts were ordered for a vehicle equipped with A750 in 2003 & up 4runner and are also used in a wide variety of vehicles.

Note the shouldered bolt & non shouldered bolts are different colors but opposite of the other set of bolts in figures 1 & 2.

Moving to a different subject all together, I was thinking of other topics to write about when this thought popped into my head: What transmission failures or broken parts have I seen in my career that I have only seen once? Surely if I have seen it once that is not the only time it has ever happened. So here are some parts failures on 4R100s & E4ODs that I have only seen once.

It is part of a normal overhaul on these transmissions to address the wear at the case and center support by machining down the support & installing a snap ring inside the case. This not only reclaims the parts (case & support), but it makes for a better transmission by helping to distribute the load over the whole outside diameter of the support.

Here is a picture of an overdrive intermediate piston housing that has a hairline crack in it due to a much worn case & support. The housing got to rocking up & down so much that it cracked at the bottom of the overdrive feed bolt hole.

This other picture is not of an actual broken case but where I have seen them crack due to the same wear issue of the case and support or over-torquing the feed bolts during previous rebuilds. In both the forward & overdrive feed bolt whole pockets on separate occasions I have seen small crack. These cracks were almost impossible to see when inspecting the case empty. It was only after you torque the bolts & sucked the case down to the supports that the cracks were noticeable… yep, after you are almost completely done building the transmission & you will not catch this on a routine air test though the bolts.

I have also seen Loctite build up give a false torque reading on the feed bolts and the shoulder of the bolt never seals against the case. The problem is a combination of old Loctite in the hole & the new Loctite on the new bolts creating too much resistance. A build tip that can catch this is before you install the separator plate with transmission V.B. mating surface facing up, squirt some oil in the feed bolt hole cavities around the head of the bolt & see if it drains though to the inside of the case.