Transmission Programming Basics

By Chris Adams, Diagnostician

adams-chris-2Chris 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.

A few months ago I wrote an article about Diesel Tuners in reference to keeping the software updated and some of the issues that can arise if they aren’t. This go around I will touch on something similar but different at the same time: vehicles that have 3rd-party programming installed, but there is no tuner that you can hold onto or plug in and update. This is hardware that has the ability to pull the factory calibration from the ECM/TCM in order to be edited, and then flashed back into the ECM/TCM. HP Tuners and EFI Live are the “big-two” so to speak, and there are a few up-and-comers entering the market but for the most part these are the brands that are the most widely used and can give us some headaches.

I will start out with the disclaimer that I am in no way an expert on the use of this software, but I have been involved with it and even modified a couple of TCM’s for 6L80 units. I figured that I could touch on a few things I have encountered and maybe save someone comeback or even know when to avoid a job if you are not comfortable with it. While there are shops out there that feel confident in tuning vehicles and have the appropriate expertise, there are just as many that THINK they know what they are doing but really don’t. These are the tunes that will wreak havoc in our lives. This software is very powerful. Whether it is HP Tuners or EFI Live, they both accomplish the same thing; it’s just the user interface that differs in appearance. Just to keep it on the simple side, all of the screenshots referenced in this article will be from HP Tuners software.

So, how do you know if a vehicle’s computer has been modified with this software? Good question. The people that program the software are very smart, and this is true also with the handheld tuners. Most will not change the calibration # when you look at it with your scan tool, so this is where the website for GM comes into play. I know that everyone that goes to the yearly technical seminars from ATSG or others has heard of or seen this website. Comparing the CVN # from the website to the one shown on the scan tool is the only way I know to confirm that tuning has taken place, beyond asking the customer. If you suspect programming and the owner does either not want to admit to it, or genuinely does not know, what I have found is that if you tell them that you will be reprogramming the ECM/TCM with the factory software and the vehicle is tuned, it will wipe out the aftermarket tuning. At this point they will either spill the beans, or walk away. Programming isn’t cheap.

The 6L80/90 series units seem to be the most popular GM applications that we see, and the focus of this article. There are so many different parameters in this software that it will be impossible to show you all of them, so I will do my best to show you some examples and you can fill in the blanks from there. In this image I am highlighted on the Auto Shift Speed tab and all of the “buttons” that you see will bring up a table: “Normal” is the 1-2, 2-3 & 3-4 shift tables which will also include the downshifts of the same gears, the 5th & 6th will be the corresponding 4-5 & 5-4 or 5-6 & 6-5.


Figure 1

In the tables below, Full Throttle Shift Speed for Normal, 5th & 6th and you can see that the 2-3 shift at WOT is commanded to happen at 56mph. For an example of how a shift is disabled look at the 5-6 table as it is commanded to happen at 311mph. Since it will never see that mph, the 5-6 will not happen at WOT in a stock calibration. However, this can be changed in the software to whatever speed you want above the 4-5 command:


Figure 2

Now we can move onto Shift time, shown in the next image. This is the transition time from one ratio to another measured in seconds and uses the Turbine speed sensor for reference. As you can see, there are multiple different tables that can be accessed. Some are base tables and others are modifiers, meaning that one table can either modify, or even replace, a base table if certain parameters are met:


Figure 3

In the next image we will look at the Shift Time Torque Adder Upshift-Normal table, this is a “RPM over Torque” table. This will have a direct affect on shift feel, and the lower the number, the quicker or firmer the shift is. So in this example, at 6250 RPM’s and 295 lb-ft of Torque input the commanded shift time is .3994 Seconds. This table can be modified in several different ways; you could change the entire table by a certain percentage or a set amount of time, or even just change individual blocks to whatever you would want. One thing here that can really mess with the transmission is the torque table, or “load factoring” that is generated on the engine side of things; if the load factor is not correct it will have an adverse affect on any table that uses a torque input for calculations, very similar to a skewed MAF sensor. The shift time in these tables (the calculated total shift time that the computer wants to see) is where the shift adapts come into play. If the actual time is greater than what is commanded, the TCM will try to shorten the shift time for that load point. Although the 6 speeds work a little differently, you still can compare this to “Tap Cells” that everyone has seen on the 4L60E or 4T65E:


Figure 4

In figure 5 we see the Shift Pressure tab, and boy, what we could go into here. As defined:

  • Maximum Pressure is the maximum desired line pressure allowed. It is a cap for any shift table value and has the final say on the line pressure offset before it is used on the Force Motor Current table.
  • Maximum Pressure B: Line pressure maximum value, in some cases this value may be calibrated as actual line pressure after the regulator gain has been applied.
  • Maximum Clutch Pressure: Clutch pressure maximum value, in some cases this value may be calibrated as actual line pressure after the regulator gain has been applied.

Figure 5

In figure 6 the Max Line Pressure table is shown, and in figure 7, Base Shift Pressure 1-2 Pattern X: The base line pressure (main line feed pressure solenoid) during a shift:


Figure 6


Figure 7

The next image is the TCC Tab which has control over the TCC Pressure, Slip Speed, Adapts and Apply and release speeds:


Figure 8

I am not going to go into much detail about the TCC Tab because we need to move onto another section that I believe has more of a negative impact on a transmission lifespan, and thus more important to know.

Figure 9 shows the Torque Management tab:


Figure 9

Almost all late model electronically-controlled transmissions have Torque Management built into the software. TM comes into play during the shift transition, as even at stock power levels, the OE limits the torque input to the transmission during shifts. The “Shift Torque Factor” where it shows 1.0 is 100% TM, and that’s what it is set at from GM. This can be changed to anything lower, and in this example I changed the 2-3 to 0.500, which is 50% TM. If you look at Torque Reduction where it shows Enable/Disable, this is where you could completely eliminate TM on any of the parameters listed. Doing so is a critical mistake and has the ability to destroy a transmission, especially on a modified vehicle. It is not uncommon to see a Camaro or Corvette that is either Turbocharged or Supercharged that has 700-1200 HP at the rear wheels, and while it is possible to make a transmission survive in these vehicles, extreme attention to detail has to be used while building the transmission in addition to and modifications to the vehicle’s computer programming.

Advanced Testing via Lab Scope

By Dan Frazier, Diagnostician

frazier-danDan has been in the automotive industry for over thirty years and is an ASE Certified Master Technician. Dan has a college background in electronics engineering and specializes in diagnostics and computer controls for Certified Transmission.

I’ve always had been fascinated by technology and electronics, and I can remember the first time I used a scope. It was in my high school auto tech class, and we were being introduced to ignition waveforms using a Sun Engine Analyzer. I pulled my 1968 Barracuda up to this huge machine with all kinds of leads coming off of this big arm that hung over the engine bay and everyone in the class was overwhelmed by what was going on. It was amazing to me that my teacher could tell that my points (anyone remember points?) weren’t gapped properly and that I had a bad plug or wire on #3 cylinder simply by looking at the electrical signal on the scope.

Fast forward 40 years. Now we have 4 to 8 channel lab scopes that are built into your scan tool or laptop that are capable of storing and manipulating data at the click of a mouse. We have multiple computer systems controlling every aspect of how our vehicles operate. Just turning on a dome light requires computer requests and verifications from multiple modules. Making a transmission shift is a whole different story. If I’m the PCM or TCM, I have to know if I’m receiving the correct information from other modules, usually on some form of data bus, various sensors, and the list goes on. Same with the airbag module and ABS/Traction control module, and keeping track of what module has control over each function can be a tedious task.

A majority of the time, a lab scope is a good way to verify inputs and outputs to various controllers. Sometimes, it’s the only way. Graphing data on your scanner can reveal many things, but often scan tools are just too slow to pinpoint the problem. Using a lab scope, we can get a complete picture of the electrical signals that the module in question is receiving. Add an amp probe and a pressure transducer to the mix, and we can get a comprehensive look at the signals in real time.

Let’s take a look at a couple of cases that would seem to be simple, but turned out to be a little more involved than expected. This is where experience in diagnosing electrical signals with a scope comes into play.

The first case is a 2004 Ford F550, equipped with a 6.8 L V10 and a 4R100 transmission, with PTO. It came to me with an issue of the O/D light flashing, erratic shifting, and code P0717 (no turbine speed signal). On my initial inspection, the transmission did shift through all 4 gears, although very erratically, and the O/D light started flashing after the first couple of shift commands. I had no turbine speed sensor on the scan data, so I knew I needed to check out the TSS circuit to start with.

I usually use my ohmmeter to check for open or shorted circuits; I really don’t trust it for much else because it doesn’t send enough current through the circuit you’re testing. Voltage drop testing is preferred for finding excessive resistance from bad grounds, poor connections, etc, and you can often find a corroded wire or circuit by doing that. In this case, the sensor tested within range, but then I went to the PCM and checked the resistance between the TSS input terminal and sensor and I found an open circuit. Slam dunk, right? I knew I had a broken wire on the TSS circuit to the PCM. I installed an overlay wire from the PCM to the sensor connector at the transmission, thinking I was good to go, but no – I still had no TSS signal to the PCM.

So, what’s up? According to my ohmmeter, I had a good circuit between the PCM and the sensor. How do I verify that the circuit is capable of sending a signal to the PCM?

Actually, it’s pretty simple: The TSS sensor on this transmission, like many others, is a variable reluctance sensor. Simply put, it’s a coil of wire wound around a magnet, and any movement of a metallic object – tone ring, reluctor (there’s lots of names for them) induces a voltage as the metal crosses the tip of the sensor. It doesn’t have to have any power supplied to it, unlike a hall-effect sensor, to operate.

I took the sensor out of the transmission and hooked up my lab scope to the signal wire at the PCM. I had an assistant take a pocket screwdriver and wave it over the tip of the sensor really fast. I could see that I had a waveform (although erratic as expected) to verify that the sensor and the circuit were both intact. It looks like this:


Figure 1

You can do the same thing with a hall-effect sensor, which usually has 3 wires, power, ground and signal, just turn the key on. But a hall-effect sensor will produce a square wave of some sorts using this method instead of a sine wave.

As it turns out, there was an internal failure of the transmission. The TSS signal is generated by the teeth on the coast clutch drum, and for some reason it was not spinning although the transmission did shift through all 4 gears. Going one step further, I took a mirror and looked through the sensor mounting hole which is easily accessible on this transmission. I had an assistant start the engine and put it in drive and let the wheels spin – sure enough I could see the drum spin for about 2 seconds and then came to a stop. I didn’t tear the unit down to determine the exact cause of the failure, but I knew from the scope data and visual inspection that it was an internal issue.

The next case is very similar: a 2006 Ford Focus that another shop had installed a reman unit into and would turn on the MIL after about a mile or so of driving, and set code P0721 (excessive noise on the output speed sensor circuit). It shifted fine and graphing the OSS showed no glitches or dropouts of the signal. This turned out to be a man-made failure – a self-inflicted gunshot wound, if you will. Here’s a picture of the waveform from the output speed sensor:


Figure 2

Notice the one hump in the waveform that the amplitude is about 1/2 of what it should be where the cursors are? What had happened was that the tone ring for the OSS got slightly bent somewhere during the re-manufacturing process. As you can see by another picture, the tone ring under the side bearing could very easily get one of its teeth bent, and it wouldn’t take much of a bump to bend one enough to disrupt the signal:


Figure 3

I actually tried to measure the depth of the teeth through the mounting hole for the OSS with a caliper – it’s pretty easily accessible – but couldn’t really identify the bent tooth. This puppy couldn’t have been bent more than .015″. I even tried to bend another tooth up to provide a point of reference, thinking if I could find my high tooth, I could count the number of teeth to my low tooth and try to pull it up with a pick. It just didn’t work out; I was trying any means possible to have to avoid R&R the transmission, but no dice.

There are many times, unfortunately, that a simple mistake can lead to a complicated diagnosis. Anyone ever seen a late 90’s Jeep flexplate disrupt the crank sensor signal because someone got in a hurry and bent the window on the flex-plate ever so slightly, but just enough to cause a misfire? Ever had a cylinder head come back from the machine shop with the cam sensor reluctors bolted to the wrong cams? Or one of my favorites, a used car lot swaps a 2.7 L Chrysler motor from the wrong year and the cam sensor signals are entirely incompatible due to design and computer strategy? That all comes from my days in general repair, but it’s things like that that applies to everyday situations and can usually only be found with a lab scope.

So, how do we know what a good scope pattern looks like vs a bad one? Firstly, there may be many good known waveforms already stored on your scan tool or scope. Secondly, there are a lot of known good and bad waveforms on websites or in factory service information. One of my favorites is IATN as that site has a pretty extensive library of waveforms, scan data, and input from thousands of automotive professionals like us. Lastly, use your scope when you get the time to look at a known good waveform, whether it be checking current to an EPC solenoid, or voltage to a shift solenoid for a voltage spike. The more you use it, the easier it becomes to get proficient at diagnosing electrical problems, and everyone profits from it.

Beware of Technical Misinformation

By Randy Peterson, Diagnostician

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

As with most of the accounts we’ve shared detailing vehicle symptoms and repairs, electrical issues seem to be the most common root cause. Our subject today involves a 2003 Dodge Sprinter 2500 that showed up at our door with the customer informing us that they could not shut it off since it would not restart without jumping the solenoid on the starter. The gentleman stated it would not start with the key, the shifter would not come out of park and the transmission would not shift. He also stated that we had installed a TCM approximately a year ago, and since it did not shift the customer thought it was related to what we had done. He also stated he had replaced the fuse in the fuse panel for the transmission and that didn’t help. Apparently, we needed to diagnose some electrical problems.

I began this adventure by scanning the computers for codes. There was a grocery list of codes stored and several communications (U-type) codes including, “No Communication from TCM”. I confirmed that the starter would not crank by cycling the key. I was told it would start by jumping the solenoid, so I knew there was battery power to the starter. Examining the wiring diagram for the starting circuit, I determined that I would need to start by checking the circuit at the starter motor relay.

I observed battery power to the relay pin 87 and pin 86 in the “crank” position. When I cycled the key, however, the ECM was not grounding the relay at pin 85. I replaced the relay with a relay jumper (see fig. 1) so I could easily start the vehicle to test it and move it around. But I needed to find out why the ECM was not providing a ground signal to the relay.


Figure 1

The ECM was located and a quick visual inspection revealed heavy corrosion on one of the connectors. The ECM terminals and the pins in the connector were in poor condition. I thought maybe the connector would need to be replaced. The connector was cleaned and I also cleaned each pin in the ECM until the corrosion was gone. The terminals in the connector were not as bad as originally thought. As I reconnected the ECM I was hopeful that this would fix the vehicle. Unfortunately, that was not the case. The engine still would not crank while cycling the key.

Studying the wiring diagram more closely, I concluded that there must be some input causing the ECM to inhibit the ground to the relay to allow the starter to energize. If I bypassed the ECM and grounded pin 43 (see fig. 2), the vehicle would crank and start. However, the shifter still didn’t work. I needed to figure out what inputs the ECM used to determine whether to inhibit or allow the crank event. I also needed to address the “No Communication” code in the TCM (see fig. 3), hoping that resolving that issue may take care of the other symptoms also.


Figure 2


Figure 3

I double-checked for B+ at fuse #2 (see fig. 4 & 5), which was the one that the customer replaced. It was the only new fuse in the fuse box. I checked the fuse box cover and it confirmed the fuse replaced should be the transmission fuse. Examining the wiring diagram of the transmission power distribution, I could see that the transmission relay powers the TCM and the shifter assembly. A bad TCM relay could certainly cause the customer’s symptoms, so I checked my voltage and grounds at the TCM. I had no B+ at pin 29 (transmission relay output). I located the transmission relay and discovered that no B+ was present at pin 87 (should be hot at all times), but did have B+ at pin 86 with the key in the run position.


Figure 4


Figure 5

Tracing the red wire from the relay box (pin 87 of the transmission relay) to the fuse box under the seat, I found that the wire did not go to the fuse marked “transmission” (fuse #2) as the diagram indicated it should. Instead, it lead to fuse #4, which turned out to be the actual transmission fuse (see fig. 6). There was B+ at the fuse but nothing coming out of the fuse. The fuse “looked” ok. I cleaned the terminals in the fuse box, replaced with a new fuse and everything started working. The engine cranked and started. The shifter interlock was now functioning correctly. After clearing codes and road testing, I confirmed that the transmission itself was now operating correctly as well.


Figure 6

Since the TCM was not powering up, it could not provide the signal required to allow the ECM to enable the starter crank circuit, and in addition, provide voltage to the shifter and transmission.

The most difficult part of this diagnosis was the lack of accurate information. I was misled on several occasions because the manuals were incorrect, and had to back track to figure out what went where. Incorrect wire colors and wrong pin locations make diagnosing difficult. It’s a part of our industry. After studying the diagrams running the test, if you don’t get the results you were looking for, you may have to start at the beginning and work your way through it. Had I tested all of the fuses in the beginning, I likely would have found the issue then. As they say, hindsight is 20/20.

The Case of the Cold TCM

By LJ Porter, Diagnostician

porter-ljLJ has worked for Certified Transmission for over 20 years and is an ASE-certified technician in transmissions, transaxles, manual transmission, steering, suspension and brakes. He was a remove-and-replace (R&R) technician for 6 years and has been a diagnostician since 1996.

A couple months ago we had a customer contact us about a problem that he was having with his 2000 Nissan Frontier 4wd Pickup. While he had some trouble explaining the exact symptoms that were occurring, we understood that the problem only seemed to happen when it was driven first thing in the morning, and that in simple terms, “it just didn’t want to go”. We arranged an appointment for him to drop off the vehicle with us so we could perform our initial diagnosis and evaluation after the vehicle sat outside overnight.

On the initial road test the truck seemed to drive out okay, but there was what I felt to be a slight bind up on the 1-2 shift with all else seeming normal. The next step was to get the truck into a service bay, check fluid, do a battery and charging system analysis, undercar inspection, and scan for codes. The findings of this initial evaluation indicated that the fluid was full but dark, and had a very slight burnt odor. The following codes appeared: P0325 (knock sensor), P0720 (VSS), P0725 (engine speed sensor), and P0732 (gear ratio error 2nd). There were no signs of water or glycol intrusion into the unit. While having an engine side code that related to an engine speed sensor and also the knock sensor code, I felt at this time the best course of action would be to refer him to a general repair shop to complete the engine drivability diagnosis.

The repair facility phoned us after they completed the engine-related repairs and said that there still seemed to be an issue with the transmission, so we went down and picked up the truck for further evaluation. While I could not reproduce the P0732 code, it still had a bind on the 1-2 that kept getting worse the more that I drove it. At this point, I recommended that we install one of our remanufactured transmissions. The manager sold the job and we got the transmission installed, completed the road test procedure, double-checked the complete repair and the truck was delivered to the customer. A few days later the vehicle owner called us and said that the issue had returned and the vehicle was behaving exactly as it had before the transmission was installed. This is the call we all hate to receive.

When he returned the truck for us to inspect, he stated that when he first started it up in the morning the OD light flashed very quickly and the vehicle did not have any power. The next morning was really cold and ideal for duplicating the customer’s concern. When I started the truck, I verified the customer’s concern as the OD light was blinking rapidly and the transmission was in failsafe. I noticed that the OD light seemed to be abnormally dim, but by the time I got the truck into the bay and hooked up the scan tool the OD light had stopped blinking. I scanned for codes and found none, and truck was no longer in fail-safe mode and seemed to drive normally at that point. So what changed? I did not move anything and didn’t even open the hood, so how did it fix itself? This was puzzling.

Once again I left the truck outside in the cold for several hours until the problem reoccurred, and when I hooked up the scanner I discovered that the scan tool had no communication with the TCM (Figure 1). Communication was okay with the ECM and ABS modules, but not the TCM. I proceeded to check the power and grounds to the TCM, and all connections and wiring seemed to be in order. By the time I got done with these checks, I realized that the TCM was communicating again with no codes stored.


Figure 1

The only solid lead that I had was that I could always reproduce the issue when the vehicle was cold, and the TCM had no communication which seemed to be at the heart of the problem. Focusing on the TCM itself, I removed the module from the truck and placed it into the freezer, leaving the truck inside our warm shop. After a couple of hours, I retrieved the TCM from the freezer and reinstalled it into the truck, and voilà! The OD light was dimly blinking and the TCM had no communication with the scan tool.

To speed up the process and test the theory, I grabbed my heat gun and started warming up the TCM (Figure 2) and fairly quickly regained communication with the TCM.


Figure 2

It also had a P1605 code in the ECM (Figure 3). I repeated this testing sequence again just to make certain that this was indeed the problem, and sure enough, got the exact same results.


Figure 3

A new TCM for this vehicle is a 2000 model year-only application and was priced at more than $500.00. Since I had never replaced a TCM for this application and none of our other 14 locations had either, I figured that a used TCM would be a fairly safe bet and picked one up at a local salvage yard for $75.00. I installed the used part and everything worked as it should. Just to be on the safe side, I took the used TCM and dropped that in the freezer also and it worked even when frozen. We returned the truck to the happy customer a couple of months ago, and the vehicle owner reports that all is well.

In the end, the experience was a very unusual one. The decision to replace the transmission was in part due to the fluid condition, but the root of the problem came down to intermittent TCM operation caused by cold temperature conditions. The key to solving these types of issues is to remain persistent and find the common links to the problem. If you can isolate the clues to a handful of repeatable conditions, it won’t be long before you solve the problem and win the customer.

Remember To Update Those Tuners

By Chris Adams, Diagnostician

adams-chris-2Chris 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 is also holds ASE Master and L1 certifications.

We all know how important it is to make sure that the vehicles that come into your shop have the latest software loaded into the vehicle’s computer systems. No matter the make or model, they almost all have some kind of updated calibration that the OE decided was important enough for them to get the calibration approved and released, whether it be for drivability, fuel mileage, durability or just a software bug.

I have been reprogramming automotive computers since 2006 and have seen hundreds of actual fixes from software updates, while others are more “behind the scenes”. In those cases you might not really notice anything remarkable after the update, but this doesn’t necessarily make them any less important than one in which you can actually see or feel a change in operation. While reprogramming ECUs is not the focus of this article, it’s an important introduction to the prime subject: tuners!

Diesel tuners of the “programmer” or “downloader” variety where you actually plug into the vehicles OBD2 port and reprogram the ECM/PCM or TCM have some of the same issues that the OEM must deal with. Since most third-party calibrations are based on a factory, OE calibration, the modified version is susceptible to the same issues that can arise with the OE calibration, such as drivability, bugs, durability, or maybe power output that was not as advertised, etc. Any of these issues can result in an updated calibration from the tuner manufacturer. This is where it gets even more complicated, as the OE generally issues a TSB that alerts you that there is a re-flash available, or there is some kind of way to look up the calibration that is loaded in the vehicle and see if there is one more current.

In the aftermarket, this same information is not readily available and you won’t know if there is a update to the tuner until you install the updating software and plug in the device. It will then compare the files loaded on the tuner to the most current files that are available from the tuner manufacturer and inform you if there is an update, or not. I will tell you that in my experience, most owners will install the tuner and forget it. If I had to put a number on it I would say that 85-90% of all the tuners I have checked for updates were NOT current.

All of the software to update the tuners is available free of charge to download and install. I have not come across one that there was a fee to do so. Doing this will accomplish a couple things: Firstly, you have assurance that all the software on the vehicle is current, and secondly, add additional revenue for the shop. We usually charge at least an hour at our diagnostic labor rate to load the tuner with the latest updates in addition to the actual charge for reprogramming. The only “hardware” you need is usually in the box with the tuner, and if not, the items are readily available as most are a USB to micro USB cable, a USB printer cable, or a micro SD card to USB adapter. These items cover just about every tuner out there.

It’s always a good idea to refer to the instructions from the tuner manufacturer for specific procedures. A general rule of thumb that I follow is to uninstall the tuner from vehicle, reprogram the vehicle’s ECM/TCM with the latest available OE calibration (whether you are using a factory tool or a J2534 interface), update the tuner, then reinstall the tuner back into the vehicle. The first step is very important to uninstall the tuner, as this will “unlock” or “un-marry” the tuner from the vehicle. Not doing so can lock the tuner to where it can’t be reinstalled until unlocked again, and there is usually a charge from the manufacturer for this. Finally, hook up a line pressure gauge to the unit when you go for a test drive! A large majority of the tuner-related problems that I have seen involve improper line pressure, either too high, too low, or a slow response in line rise. These will create shifting issues and/or premature failure of the transmission, if not addressed.

I have included links where you can find the updating software to some of the more popular units:

Here is a real-life example of why this process is important. A 2009 Dodge Ram 2500 6.7L diesel with a 68RFE transmission came into one of our locations with some shifting issues. This was a modified truck with the EGR/DPF deleted (very common modification), bigger injectors and an H&S Mini Maxx tuner. This particular tuner has optional transmission tuning software that is available for an additional charge. Under the “settings menu”, this truck had the transmission tuning displayed as “unlocked”, so I knew that the tuner was in fact installed with this option.

I wanted to eliminate the tuner from the equation, so I uninstalled the tuner from the truck (when you do this the tuner will reinstall the calibration that it saved when the tuner was originally installed) and continued on with the evaluation. Uninstalling the tuner did not fix the problem, but I did notice something pretty strange with the data from the scan tool:


Figure 1

While under a load from 60-80 mph, the actual line pressure was correct but the desired line pressure goes as high as 220 psi. Since OE programming only commands a maximum of 160 psi in forward gears, the displayed desired 220 psi is obviously incorrect. I did verify with a pressure gauge that the actual sensor reading was correct and also tested with two different scan tools. The truck was not setting any low pressure codes, and uninstalling the tuner should have returned the vehicle to stock. What I was seeing did not match what I have seen in countless other trucks with the same drive-train, but why?

I went through the process of installing and uninstalling the tuner again with the same results, and looking on the Chrysler Tech Authority website I found a PDF file that you can download and save to search for calibration updates. The calibration in this truck showed as being current, so at this point I had no other choice but to force reprogramming with the same calibration number into the TCM (I say “force” because the system typically won’t reprogram if it detects that the loaded calibration is current, as this was). I used the Chrysler WiTech scan tool to do this, and after using the factory tool to reprogram the TCM, you see the new results here:


Figure 2

You can see that the actual and the desired line pressure parameters now match each other. I concluded that using the tuner to “return vehicle to stock” did not reinstall the original calibration in its entirety and there was a residual effect on the factory line pressure table.

This particular tuner calibration had been updated multiple times, and one of the modifications they had done had altered the line pressure table. Here is a quote from H&S: Low Boost Fueling Option – This was added as an attempt to mock the feel of the old Pedal Response option that was omitted due to trans line pressure rise issues when we used that option.” The subject truck ultimately had an OD clutch failure. Can I 100% prove that a tuner that was not updated caused the failure? Not really, but when an update is released to fix a line pressure rise problem I think it’s a good possibility that had a negative effect.

In summary, it’s always important to ensure that all of the updateable software is current on the vehicle, regardless if OE or aftermarket tuning is installed. Diesel owners commonly go for use of tuners in conjunction with engine component adds/deletes to get the maximum performance out of their trucks. The OEMs are wise to this practice and make it difficult for third-party tuners to alter some of the calibration parameters. Incorrect line rise is the prime killer for transmissions working under these conditions, so ensuring it’s correct is in everyone’s best interest.

Diagnose using application charts

By Barry Bartlett, Diagnostician

bartlett-barryBarry has over 45 years of automotive experience. He has done everything from managing, owning, and operating his own general repair facility to working in the transmission industry. He’s a ASE Master tech. with L1 advanced level diagnostics, the highest level of certification available. Barry and his wife Janet have been married 42 years and are proud parents of 6 children and 26 grandchildren.

One of the best and easiest diagnostic tools that I use almost daily for diagnosing transmission problems is pass book or application chart information. When I have a shifting issue, a review of what solenoids and friction elements are applied in each gear can let me see what areas of the transmission the problem may be caused by, so I can then differentiate whether there is an electrical or mechanical issue causing the symptoms.


I will use the 4L60E transmission for the following scenarios (refer to FIG. 1):

Third Gear Neutralization

If the vehicle is shifting to first and second gear and feels like it neutrals when third is commanded, a review of the solenoids shows that both are on for first gear, so I know that both are turning on. When second gear is commanded, SSA turns off. In third gear both solenoids are off, so when I feel the neutral condition, it is a good sign that SSB is turning off so I can then conclude that both solenoids are working properly.

Testing further, I know that on the shift from second to third gear that the 2-4 band turns off and the 3-4 clutch applies. Next, I shift to manual second while increasing the vehicle speed until about 40mph, then shift to overdrive and let off the gas. If I have a second gear ratio when fourth gear is commanded, it will reveal the cause: the 3-4 clutch is not holding. Referring to the chart, I see that the 2-4 band applies at this point. If the 3-4 clutch does not hold, the transmission remains in second gear because the forward clutch and the 2-4 band are holding, thus indicating that the 3-4 clutch is not.

No Movement from Stop

If I have no movement from a stop I can test to see whether the forward clutch is bad, or if the forward sprag clutch is not holding, by shifting into manual low. If there is now movement, the forward sprag is bad because the overrunning clutch holds the sprag, but if it still does not move then it is the forward clutch causing the concern.

No Second or Fourth Gears

If I am missing second and fourth gears but all other gears are ok, the cause points to the 2-4 band not applying. Many times I have had customers complain that their transmission stays in first gear for a long time before it finally shifts, and some will report that they have to let off the gas pedal in order to get it to shift. They might think that it is then in second gear, but they are actually in third gear and may not notice that there is no upshift into fourth gear.

Remember that in first gear both shift solenoids are on and in third gear, both are off. That would indicate that the solenoids are working ok and point to a friction element, and as the chart shows, the common element applied in second and fourth gears is the 2-4 band. The 2-4 band holds the sun shell. Sometimes the sun gear will break away from the sun shell on the 4L60E units and you will lose second, fourth, and reverse gears which then require the replacement of the sun shell.

Forwards but No Reverse

What if I have all forward gears but no reverse? A look at the application chart shows that the reverse input clutch and the low/rev clutch engage to engage reverse gear. An easy way to test this is to accelerate to about 20mph and pull it into manual low to see if you have engine braking when you let off the gas. If engine braking is working, that indicates that the low/rev clutch is correctly holding the sprag clutch from overrunning. This would indicate that the reverse input clutch is the cause. If you do not have engine braking, it points to the low/rev clutch being bad and preventing reverse. It is good to confirm the integrity of a sprag clutch before performing a rebuild, because you may not be able to tell when the transmission is disassembled and you are holding it in your hand.

In addition, the chart can be helpful if you suspect a component problem. For example, a review of the solenoid application chart will show the outcome if shift solenoid A (SSA) is not turning on: second gear starts and the transmission will shift into third, but if SSA is not turning on you will also have no fourth gear. Second and third gears would be the only forward gears that function.

If shift solenoid B (SSB) is not turning on, the solenoid chart shows that the transmission would have fourth gear starts, and manual second and third gears at about 30mph. When shifting up from manual second to third or overdrive gear, I will have fourth gear when the computer commands because the SSA is working.

What is the effect if there is no power to any of the solenoids? We would have third gear with no upshift or downshift when in drive. Manual second would function because it is hydraulically shifted into second gear without solenoids, but in drive or overdrive we would have only third gear because no solenoids are turned functioning. I can look then know to look for electrical/control problems.

When there is no power to the solenoids it will generally set multiple solenoid codes on any transmission, so check fuses and ensure there is power through them, then check for power at the transmission connector. If no power at the fuse you could have an ignition switch problem (common on Chevrolet), but if no power at the transmission fuse, check your power distribution to identify where the power is sourced to the fuse.

On most GM trucks and cars you can actuate the solenoids with a scan tool and listen for the solenoid to click (both solenoids can be tested in this manner) and let you know that they are working and that the computer has the capability of turning them on and off.

Some vehicles will shut off power to the transmission when it has a code set by turning off the relay that supplies power to the transmission, so be sure to look for codes that could be causing a limp-mode condition. This is commonly seen on 604 Chrysler transmissions, where in limp mode it will shut off the relay leaving reverse and second gear only. Look for codes and see if there is a speed sensor, pressure switch problem, or some other issue causing the limp-mode condition.

It is also a good idea to monitor the status of the solenoids for the proper gear, because I have had defective computers give false information showing that they are calling for a certain gear on the scan tool, but yet not turning on the solenoids that are needed for that gear. I often tap into the wires with lab scope, voltmeter or test lights to make sure that the computer is turning on and off at the correct time.

Many transmissions now use pulse width modulated solenoids so instead of on and off  the chart may show high and low pressure and/or high or low amperage. Also you might see on the application chart “N.O.” which stands for “normally open”, and “N.C.” which stands for “normally closed.”

There are several sources to obtain the Passbooks and charts referenced in this article. Collecting application charts and saving them for future reference can help with the diagnosis of any transmission, and can make your recommendation for repairs much easier. As you become acquainted with and review application charts, you will find diagnosing transmission shift issues easier and quicker to pinpoint.

Common Symptom, Uncommon Cause: Shorted Sensor Defeats Electronic Controls

By Dan Frazier, Diagnostician

frazier-danDan has been in the automotive industry over thirty years and is an ASE Certified Master Technician. Dan has a college background in electronics engineering and specializes in diagnostics and computer controls.

The subject of this article is a 2006 Hyundai Sonata that came into our shop with a no-shift complaint. It was likely in limp-in mode, so in order to get down to the cause of the problem I began with a cursory preliminary inspection.

My initial inspection revealed several obvious issues: the MIL didn’t self-check, no communication with the PCM/TCM unit, airbag light on, and an oddly flashing cruise lamp. A short road-test confirmed the no-shift condition. After getting some diagnostic time approved from the customer, I began my in-depth diagnosis.

Whenever I’m faced with a communication issue, usually the first place I go is verifying power, ground, input and output to the offending modules. A good place to start is checking communication lines at the DLC and checking fuses. And I mean ALL of the fuses. Not that I’ve ever had a “D’oh!” moment after 30 minutes of checking things, but it happens to the best of us. I quickly found a blown fuse that was labeled B/U lamps. Replacing it blew the new fuse immediately, so I knew I needed to look there first.

Looking at a power distribution diagram showed that fuse powering the B/U lamp circuit also powers what Hyundai calls pulse generators ‘A’ and ‘B’, or more commonly known as transmission input and output speed sensors. In addition, the transaxle range switch and the vehicle speed sensor are also powered through this fuse. All of these components are easily accessible on the top of the transmission, and it didn’t take long to find the connector to the pulse generator melted:


Figure 1

The pulse generator sensor is a hall-effect sensor with a power and ground, and the output feeds the K-line, or low speed communication circuit.

Here’s where the fun began. The vehicle speed sensor on the transmission doesn’t supply vehicle speed data directly to the PCM. It sends data via the K-line to the BCM, TPMS, ABS, and traction control modules. Vehicle speed input to the PCM comes from the RF wheel speed sensor, which is basically an ABS sensor, even though the vehicle doesn’t have ABS. This is a rather odd, but common, setup on Hyundai/Kia vehicles. Side note: if you run across one that has an erratic wheel speed sensor signal due to a cracked tone ring, the rings are available separately from the dealer, are very inexpensive and usually on the shelf.

The K-line also supplies scan tool communication. When the sensor and connector melted in this case, it grounded the K-line circuit and therefore, no communication. Once I snipped the connector off, communication was restored and I was able to scan for codes. The only code that showed up was a P0700, general transmission fault. I didn’t have a code for the pulse generator because it wasn’t an input to the PCM/TCM. I still didn’t have any communication with the TCM, nor did I have a check engine light or a code for the MIL circuit. Time to dig a little deeper into the problem.

One thing I like about Hyundai/Kia vehicles is that for the most part, they’re pretty easy to work on. Also, their electronics seem to be pretty reliable, as is the case with most of their Asian counterparts. They don’t seem to have very many intermittent issues like some domestic manufacturers (think TIPM!) and their components are usually either dead or alive.

The PCM/TCM units on this model are next to the air cleaner with the connectors facing up, which makes back-probing circuits a breeze. In about 5 minutes I had the instrument cluster out and knee bolster removed in order to provide access to the fuse/central junction block. I now had easy access to test just about any circuit on the vehicle. With the cluster out, it didn’t take long to diagnose the cause of the MIL issue; you can’t light up what isn’t there. The socket and bulb was missing from the back of the cluster:


Figure 2

These bulbs are not sold separately from the dealer; you have to buy the whole cluster. Moving forward with diagnosis, it didn’t take long to verify powers, grounds and data lines to the PCM/TCM, and they all tested okay. The TCM side of the PCM/TCM unit itself was apparently dead.

The hardest part of this diagnosis so far was finding complete information within the wiring diagrams and service information. The pulse generator in the transmission only appears in the power distribution and computer data line schematics; if I hadn’t already known its function, I would have had a very hard time finding it and description and operation of that component is virtually non-existent. The pin and wiring assignment for the DLC is backwards (like a mirror image) and some of the pin assignments and wire colors at the PCM were wrong. This seems to be a somewhat common issue. If you’ve spent much time looking at the O.E. service information, you would know it can range from very frustrating to downright hilarious. If you see something that looks wrong, it very well may be. Double-check it against another source – it does happen more than infrequently.

The used car lot that brought us this jewel was a pretty good customer, but had a reputation for wanting to fix the bare minimum as most car lots do. As expected, all he wanted to do was make it shift. In fact, he showed up just before closing time with a used PCM/TCM unit in his hand. Installing a used module is usually a crapshoot – I don’t recommend it – but we told him we would give it a try. We ordered a speed sensor, but finding a connector pigtail was a different story. Hyundai/Kia, like Nissan and a few other OEMs, don’t offer connector repair replacements. You would have to buy the whole harness, kind of like the bulb in the cluster. I have sourced those bulbs in the aftermarket before, but wiring pigtails are slim pickings. We ended up having to send one of our guys to a salvage yard to clip one off of a donor vehicle, and charged accordingly for it.

After our parts arrived and were installed, the Sonata shifted normally, but did set a code – P0630 – for VIN programming error. You would’ve never known it because of the missing check engine light bulb. We possibly could have resolved that issue with a reprogram of the PCM, but as expected, the customer didn’t want to spend any more money than necessary to get it rolling. It was somewhat of a challenge getting through the service information, but turned out to be a fairly easy and profitable job.

The shorted pulse generator created a situation that damaged the TCM electronics, and the vehicle was tampered with to hide the issue. Auction cars are often technical throwaways that somebody didn’t want to deal with. You have to expect the unexpected. A little research and detective work go a long way in these cases.

The Case of the Output Speed Sensor Spike

By Dana Deeke, Diagnostician

deeke-danaDana joined Certified Transmission in 1991. Dana has worked in all positions at the Lincoln location, starting as an R&R technician and is now our current diagnostician for our Lincoln, NE facility. He enjoys car racing and spending time with family and friends.

Occasionally you will have a vehicle come into your shop that takes you down a different path than what you might have expected. The following account tells the story of one of the times that it happened to me. The star of this show is a 2006 Chevrolet Silverado 2500 4×4, equipped with a Duramax diesel engine and an Allison transmission.

The information on the checkout sheet stated that the customer had a concern of truck being sluggish from a stop and slipping or no 6th gear. The customer also stated that the transmission had been replaced approximately 30,000 miles prior to his visit. The truck had been to another shop previously and the customer was told that the transmission was failing.

Armed with an understanding of the customer’s concerns, I started the diagnostic process like I always do by hooking up the scan tool and checking for any trouble codes. The code check revealed P0729 and P0733. P0729 shows up as a ratio error in 6th gear, and the P0733 is 3rd gear ratio error. A quick check of the fluid indicated that it was full, red, and had no burnt odor. I took the truck out for a road test with the codes in memory, and much to my dismay, the truck functioned properly and nothing on the data stream appeared out of the ordinary, including the output speed sensor signal.

Next I decided to clear the codes and drive it with a graph on the input speed, output speed and current gear. The truck shifted through all the ranges properly, and the speed sensor graph looked clean and smooth and no codes were set:

Figure 1

Figure 1

Somewhat frustrated, I pulled into a parking lot and looked through some of the other PIDs hoping to see something unusual. Upon pulling into the parking lot, I did not put the truck in park, instead simply idling in drive. The next step was the first in finding the problem. Like most techs, I am always trying to listen and feel what is going on with a vehicle. As I sat there I thought I’d heard a slight exhaust leak, and I would want to note it on the paper work if there was one. I decided to power brake the truck a bit to see if I could hear where the leak might be coming from, and that’s when I saw it: a momentary spike on the output speed sensor graph, and even better yet, I was able to make it happen fairly regularly. During this screenshot the truck remained completely stationary:

Figure 2

Figure 2

Now the question that needed answered was what was causing it? I noticed that the spike in the output speed signal would happen whenever the input speed signal increased. My first thought was, is there voltage that is being induced into the output speed sensor circuit? Once I was back at the shop I pulled up a wiring diagram of the transmission circuit and I also wanted to see what the routing of the input and output speed sensors wires looked like.

Looking at the wiring on the truck itself, I couldn’t see any routing issues and testing did not show any signal transfer from the input sensor. While I was looking things over, I checked chassis grounds and even removed the serpentine belt to make sure there was not any static charge that may have been causing voltage problems. Removing the belt did not have any effect on my concern. I thought about some of the Chrysler vehicles I had seen with excessive alternator ripple causing phantom voltage in the output speed sensor signal. Though I had never seen this on this type of vehicle, I decided to run an alternator charging output and ripple test, and everything passed with flying colors.

With the help of an assistant, we unplugged the output speed sensor from the transfer case and did the power brake test again. As expected, I could not get the output speed sensor to spike. Next, we plugged the sensor back in and did the power brake test again and it confirmed that the spike returned. Next we removed the sensor but this time we left it plugged in, again did the power brake, no spike occurred. So the sensor had to be in the transfer case for the symptom to happen. Based on what we were seeing (and not seeing), it was determined that the transfer case itself was the culprit.

This truck had a lot of miles on it and as far as we could tell it had never had a transfer case replacement. There was enough wear inside to allow the output shaft to move around when the torque of the diesel was applied causing a false output signal to be generated.

At the beginning of the testing, the symptoms and data appeared to point to something electrical causing the problems, but in the end it was a purely mechanical issue; one that was not related to the transmission at all. We installed a remanufactured transfer case, did multiple road tests, and confirmed that the symptom had been corrected. The customer was happy that his “transmission” problem had been corrected.

As demonstrated here, the symptoms don’t always lead you down the right path. In many cases you will need to leave the familiar path and go down the road less traveled. If not for the spike being witnessed during the testing, this issue may have been impossible to find. Always watch for clues and don’t ignore the unusual. Sometimes we have to be more of a detective, rather than a tech.

Surges in a 2006 Chevrolet Impala

By Chris Adams, Lead Diagnostician

adams-chris-2Chris Adams started with Certified in 1986 as an R&R technician. He has an Associate Degree in Automotive Technology from SCC in Milford, NE. He also holds the ASE master tech with the L1 certification. Currently he is our diagnostic trainer and is responsible for keeping our diagnostic techs at the retail locations at the top of their field, and keeping current with all the latest trends and tools in our industry. Chris also works closely with the technical dept at the remanufacturing plant and helps coordinate our fleet of research and development vehicles for testing.

Recently a 2006 Chevrolet Impala came into one of our retail locations with a surge complaint while cruising on the highway between 60-65 mph. I drove the vehicle with the customer to verify the concern and was able to duplicate the circumstances in which the vehicle acted up. While watching the tachometer I noted that there was a noticeable 150-200 rpm surge while TCC was applied. It felt like a typical TCC surge as a result from a leak in the TCC regulator circuit, so additional diagnostic steps were in order. We discussed this with the customer, and he authorized the additional time. At this point I was fairly convinced that we were going to need to go inside the unit.

We always start our evaluation with some pretty basic steps: check fluid level and condition, scan for codes, perform a battery and charging system test, and an undercar inspection. At this point everything was looking good, fluid was full and clean, there were no DTCs for the engine or transmission, and the battery and charging system test results came back error-free, and there were no obvious problems shown with the visual inspection.

At this point we proceeded to take the vehicle out for a road test with the scan tool connected so that I could monitor the PIDS for the TCC command while looking at the TCC duty-cycle while the surge was occurring. It appeared that the PCM was commanding the change, although it was very erratic. Given this information, I now had to try to figure out what PCM inputs could be causing this to happen.

After a few considerations, I turned my attention to the TPS signal. Utilizing a Snap-On Verus Pro scan tool there is a PID called, “CALC TPS %” and while monitoring this value, I saw what was making the PCM vary the duty-cycle and therefore causing the TCC surge. There was a noticeable jump in the TPS signal when the surge was happening (Figure 1). As this is a “drive by wire” system, I also looked at the APP signal and it was smooth. Further testing was now in order.


Figure 1

After looking over the circuit wiring diagram and connector view from GM Service Information, and also checking for pertinent TSBs, I hooked up the scope right at the throttle body to TPS1 and TPS2. At a throttle position just a little off idle, I could see the glitch in the signal in both of the inputs (Figure 2). After verifying there were no ground issues I was leaning toward recommending that the throttle body be replaced. One last thing I needed to check was if there were any updates to the PCM calibration. Checking the current calibration against the GM TDS website, I noted that there were several updates to the calibration, although none of them relative toward the issue that I was having.

Figure 2

Figure 2

My recommendations for repair included a pan inspection & fluid/filter change, a replacement AC Delco throttle body, and reprogramming of the PCM. All repairs were authorized by the customer and we proceeded with the repair. After my recommended repairs, drivability was normal, data signals were smooth, and the TCC surge was gone. The vehicle was then returned to the customer. Another one done, or so I thought.

Unfortunately, two days after the vehicle was returned to the customer, he returned with the dreaded, “It’s still doing the same thing.” I grabbed the scan tool and went for a ride with him, and this time it took quite a while for him to get the vehicle to act up and it was not a repeated surge like it was before. However, under just the right set of circumstances you could see the tach rise up by about 50 RPM. This little RPM flare would only happen at very light loads. While I could see the duty-cycle command change when this happened (Figure 3), I could find no reason for why it happened as the TPS signal was smooth.

Figure 3

Figure 3

I then recorded all the transmission data so I could go back and look at it more in depth, to no avail. We again went for another road test while I was looking at the engine side of the data and happened to catch something changing when the RPM flare occurred. This particular vehicle has the “DOD System” (Displacement On Demand) where under light load conditions it can deactivate cylinders 1 and 7 on the left bank and cylinders 4 and 6 on the right bank at cruising speed. On the scan tool there is a PID called, “Cyl deact system command” that will either show V8 or V4 and this is where I saw the change: every time that the PCM commanded a change in state from either 8Cyl mode to 4Cyl mode or vice versa there was a quick dip in the TCC duty-cycle command (Figure 3).

It was more noticeable from V8 to V4 because of the light load, when going from V4 to V8 there was an increase in load that triggers the change in state and the small flare was not as noticeable. After verifying operation on another like vehicle, I have to conclude that this is a normal operation and just a byproduct of the change in state from V8 to V4 mode and probably programmed into the software to make sure the transition is smooth so the owners do not notice a bump or jerk during this transition. Since I am not a GM engineer, this last statement is just my opinion. I have never seen anything in print to 100% verify.

Less Time Spent Diagnosing

By Richard Middleton, Diagnostician

middleton-richardRichard Middleton was a diagnostician at our Grandview, MO retail store.

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.

less-time-spent-diagnosing-0It 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.

less-time-spent-diagnosing-1I 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.