Programming a vehicle is becoming part of everyday service for most shops today. More and more problems are being addressed by software updates rather than hard part replacement by all manufacturers.
Like other vehicle technology, the reprogramming process continues to evolve, and with that evolution, problems with programming continue to occur. Some programming issues are “self-inflicted,” while others are due to vehicle issues or software conflicts.
There are some basic processes to follow to minimize the chance of issues during programming. These include:
- Use a “memory saver” to regulate and maintain battery voltage. Never use a battery charger; the voltage fluctuations can cause programming errors.
- Check the battery and replace it if needed prior to programming.
- Make sure your scan tool, pass-thru device, and computer have the correct software.
- Make sure you have a good internet connection and PC-to-pass-thru connection, preferably hard-wired to your reprogramming equipment.
- Select the correct RPO codes based on how the vehicle is equipped.
- Eliminate or disconnect aftermarket equipment that could interfere with the programming process.
- In addition, many modules now require the program be stored in a flash drive — one with at least 4GB formatted to FAT32 — because the
software loads are so large.
As of late, a number of technicians have run into problems loading software or calibrations into the TEHCM on the 6L and 6T series transmissions. A year or so ago, these units seldom experienced problems, but today, as they become more popular and as reprogramming system changes have been implemented, difficulties are showing up.
Here are a few common scenarios and how they play out:
- Scenario 1 — A vehicle comes in with an issue related to the transmission. The technicians decide a software update may address the issue, so they start to install the update. Everything goes wonderfully right up to the end when they receive an Error Message, Program Failed, indicating the software didn’t load properly.
No matter what they do from this point, the software won’t load. In addition, the transmission is now in default or limp mode. So the manager now has to explain why a vehicle that drove into the shop now can’t drive out of the shop. - Scenario 2 — A vehicle comes in with an issue related to the transmission. The customer is price-sensitive, so they decide to install a reman or salvage yard unit. Once again, everything goes fine, right up until they get an Error Message, Program Failed, and now the new transmission won’t operate properly because the system’s in default mode.
- Scenario 3 — A vehicle comes in with an issue related to the transmission. It appears to have a TEHCM problem, so the technicians replace it. Everything goes fine until they get an Error Message, Program Failed, and the transmission won’t work properly because it’s stuck in default mode.
You may already be aware that GM has Global A and Global B technology incorporated into many of their modules. You can’t swap modules in the global platform vehicles because the module ID won’t match, which will lock the module out.
The vehicles in the example scenarios aren’t global modules, but the lockout action operates as if it were a global controller platform.
When you face one of these situations, you’ll likely have codes associated with the programming failure. These codes typically aren’t the codes you’ll see on your scan tool, because your scan tool won’t be able to communicate with the TEHCM.
The codes are displayed on your computer’s reprogramming screen as part of the failed programming process. Don’t be fooled here. You may see some transmission data, but the data parameters are coming from the ECM, not the TEHCM. In addition, you may find a communication error — code U0101 — stored in some of the other modules.
Typically you’ll see one or more of these codes displayed on your computer screen:
- E4398, E4399, E4403, E4414, E4423, E4491 (E4423 and E4491 are the most common)
- M4404, M4413
All of these error codes have to do with some sort of programming failure:
- E4398 indicates a programming error due to a lack of, or incomplete, calibration data files. It typically isn’t related to a module or vehicle issue.
- E4399/M4403 is generally related to a communication loss between the module and the programming tool. This could also be due to a drop in battery voltage, aftermarket components, connections, wiring issues, or a delay or interruption in the data transmission into the module.
- E4414/M4413 is usually related to the GM programming system not recognizing the calibrations stored in the module. A “*” symbol will typically be attached to the calibration number, indicating it can recognize the calibration. Address this issue by restarting the SPS reprogramming system and selecting Replace and Reprogram as the programming method. This process overwrites the unidentified software and calibrations.
- M4404 indicates no communication with your scan tool or pass-thru device. It typically isn’t related to a module or vehicle problem. Check for proper battery voltage and for good connections between your scan tool and the PC to isolate the problem.
- E4423/E4491 are currently the most common issues. These codes indicate an incompatibility between the software or calibrations and the module. They can be due to battery voltage issues, aftermarket components, and now a previous VIN being stored in the module.
With regard to the scenarios we discussed at the beginning, these problems are often caused if the TEHCM in the transmission isn’t the same as the one the vehicle was originally equipped with, usually due to transmission or TEHCM replacement.
The VIN is one of the last bits of information written to the module, completing the software/calibration load. So, if a new VIN can’t be written, the process results in an error code at the end of the programming process.
In addition, when programming or reprogramming a TEHCM, the software and calibrations are erased as part of the process. If the program-ming process can’t be completed due to a conflict, the TEHCM won’t be able to function. That’s why the system defaults into limp mode.
Not long ago, you didn’t need to worry about a VIN being stored in the TECHM; we had ways to work around the system and overwrite a new VIN. Not any more: The GM SPS no longer allows you to overwrite an existing VIN. That means you’ll need to install a new, blank TEHCM for the calibrations to load and the transmission to operate correctly.
As this situation is becoming a common problem, you should also get familiar with the additional parts of the message that’ll be displayed on your PC when this failure occurs. These include:
- E4491 Reprogramming error! Check all connections and reset programming interface
- E4423: Unknown programming error
IMPORTANT: Don’t replace the control module immediately! First make sure your programming device is updated with the latest software and is connected properly to the service PC. Then attempt reprogramming. If the failure persists, contact technical support.
Well as you can see, times are changing and so is the technology you’re expected to work with. And it’ll continue to change, so you’ll need to change with it.
