Fixing a Chrysler suffering with automotive amnesia

Oct. 4, 2019
A Chrysler encountered a memory issue where it was unable to retain system information during a power cycle. See how we tackled the problem.

I was called to a body shop on a 2015 Chrysler 200 with a 2.4 L engine with an automatic transmission (Figure 1). The vehicle was involved in a minor collision and was moved around the shop to different bays during the repair process. The vehicle encountered an issue where it would no longer go into drive or reverse and it was stuck in the neutral position. There was no shifter handle in the vehicle, but rather a knob on the center console that was turned to select a gear. The shop did not know what caused this condition during their repair process and were not too quick to condemn the transmission. It was at this point I was hired for my diagnostic services.

Figure 1
Figure 2

When I arrived at the shop, I entered the vehicle and quickly observed a few lights on the dash with the vehicle running. The Check Engine, ABS and the Electronic Parking Brake lights were all illuminated (Figure 2). I even noticed the selector knob was indicating that the vehicle was in neutral (Figure 3). When I tried to select drive or reverse, it would not engage so it was at this point I decided to hook up my Chrysler Wi-Tech Scan Tool to make sense of it all.

Figure 3
Figure 4

The Wi-Tech uses Topology layout for the controller network. This is very helpful to the technician because it gives you a quick visual result of what is going on in the vehicle (Figure 4). The Topology map is always live and will show all control module icons in blue if there are no codes, yellow if there are codes and red if the controller is inoperative. The gray icons indicate that the controller is an option and is not used on the vehicle. Their screen showed 17 active controllers on board with seven of them indicating codes present or stored. What is also helpful on the screen is the fact that the controllers are linked by network lines they share and the lines are color coded for the types of networks they are linked to. In this case light blue is CAN Buss IHS and black is CAN Buss C. Because this scan tool is online, a green flash icon is placed over the TCM icon to indicate an available update for the transmission control module. As you can see, the Wi-Tech Tool was built with the technician in mind.

Figure 5

By selecting the “All DTCs” tab, a screen comes up with the codes for the seven controllers (Figure 5). This is where you need to decide what codes relate to the transmission engagement issue and how the problem is being resonated thru the network. The Radio Frequency Hub Code can be ignored because it a code for a tire pressure sensor fault relating to a signal output error. The transmission had codes P1500 and P0610 for configuration and vehicle option mismatch, yet the shop never replaced the TCM in their repair process. The TCM vehicle information somehow got corrupted. This was also resonated in the body control module, which stored a code B2204 for a module being corrupted on the network. The body shop did explain to me how the battery on the vehicle went very low and they constantly had to jump start the vehicle so they ended up putting a new battery in it. Apparently, this TCM had a non-volatile memory issue where it was unable to retain system info during a power cycle. It suffered an automotive amnesia attack that rendered it inoperative to perform critical tasks to propel the car forward or backward, so it chose to enter a default protection mode. The fix here was to reconfigure the TCM with its lost information and put it back to factory specifications.

Figure 6
Figure 7

I proceeded to the BCM PROXI status screen, and you can see that the TCM definitely fell out of alignment with the other controllers onboard (Figure 6). I next went to a special Guided Diagnostics menu in the Wi-Tech tool to perform a PROXI configuration alignment and configuration restoration of the transmission control module (Figure 7). Once both of these procedures were done, I was now able to switch it back into park (Figure 8). I tried putting the vehicle into reverse and drive and the transmission engaged in both gears without any issues. I did, however, alert the shop that there was a transmission update that the owner of the vehicle must be aware of. This would benefit all involved in case the customer came back with a transmission issue unrelated to the accident.

Figure 8

My problems were not over because now I still had codes in the engine, ABS, electronic power steering and emergency brake control modules all resonating an issue with the steering angle sensor. When the vehicle battery went very low, the vehicle also lost the calibration of the steering angle sensor, so I had to go into the electronic power steering menu to relearn the steering angle sensor (Figure 9). There is certain criteria that must be met prior to performing this procedure. You must perform it on a flat surface with the steering wheel in center position and the front tires pointing straight ahead. This procedure also calibrates the yaw sensor, so this is why having the vehicle on a flat surface is important. Once I performed this task, I was able to clear the entire vehicle and everything was back to normal with no parts needed. It is amazing what a scan tool can perform when you can access the trouble codes stored in a vehicle and understand how to effectively use your tool to correct them.

Figure 9

All of this could have been avoided if the shop took extra precautions to make sure the battery was properly maintained while the vehicle was in their possession. If a battery is simply disconnected for repairs and then later reconnected, the vehicle may have a fighting chance not to lose onboard learned procedures or configured information stored in certain modules. It is a problem when an electrical system is extremely powered down during a slow cranking condition where the battery power is not sufficient enough to start the vehicle. Doing this will seal the fate to lose a lot of non-volatile memories within the controllers on the networks.

There are quite a few manufacturers out there such as BMW and Mercedes that will not allow a vehicle to be cranked if the voltage on the battery falls too low. This is to protect the non-volatile memory functions of the controllers, and it can easily be mistaken for a starter relay or neutral switch fault. Manufactures don’t want a vehicle to lose all learned functions such as ABS steering angle sensor, engine idle learn, SRS passenger occupant seat weight, camera/radar calibrations or stored configuration files in critical control modules.

It would be wise to invest in a battery maintainer to put on the vehicle that’s held in your possession for the long term. If you’re going to start up a vehicle with a known low battery condition, you may want to put a booster pack on it to prevent the extremely low cranking condition from happening. You also may think twice now about leaving the key in the on position to listen to the vehicle tunes in the car while doing simple work on it. That very low battery cranking issue might just come back and bite you. I’m hoping this story hits home with a lot of techs out there and has enhanced what you know or don’t know.

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