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My apologies for the length of the following description, but when "everything electronic" goes wrong, it takes some 'spanin'. My vehicle is a 2014 JGC Diesel with just 16,000 miles on it.

While on a drive from Seattle to Idaho a few weeks ago, the first occurrence of the problem happened just as we cleared the Snoqualmie summit. This failure is best described as a one-off resulting in a constant check engine light on, ECO off indication, and Electronic Stabilization Control (ESC) off indication. In addition, the Service Shifter and Service Transmission indicator came on momentarily. All the individual gear indicator lights in the shifter handle illuminated. The radio turned off. Fault chimes enunciated. Blind spot indicator lights illuminated with no vehicle in the area. I’m sure there were others, but we didn’t note them at the time. We checked the manual, focusing on the ESC off indication which basically said that something tripped the ESC and it should clear after a few driving cycles which it did, as well as the check engine light going off, after two days of normal in-town driving.

While in Idaho doing just regular in-town driving, we could get the car to momentarily flash (drop out) the dash instrument panel coincident with left hand turns of sufficient speed, but all indications would immediately return to normal. The feeling at this time was that a loose connector or wire short was occurring. This kind of behavior is very reminiscent of a microprocessor loosing it’s ground reference.

On the way back from Idaho, we were again approaching the summit, and the instrument cluster again blanked out (no left hand turns required). Fault chimes enunciated. Park sense and blind spot lights and annunciations sounded without other vehicles around. The emergency brake light in dash illuminated. The tach dropped out to zero then back to normal. The temp indicator dropped out then back to normal. The tire pressure fault light turned on. The speedometer readout would go to zero then back to normal. The windshield wipers would cycle. The seat belt indicator would illuminate. A Service Shifter and Service Transmission indication would be displayed. The ASC illuminated. The check engine light came on. The ECO and ESC indicators again illuminated. Basically, the car was possessed!

We took the summit exit and stopped at the end of the exit. When we continued on to get to the summit businesses, the car was “stuck” in a low gear. We pulled into one of the parking lots and could not get the car out of drive – it would not go into park, reverse, nothing. Finally, I just shut off the engine.

After waiting a half hour or so, we started the car again and all seemed to be working well. By that time, I had been able to locate, via a web search, that there had been a recall on certain 2014 Jeeps which matched our symptoms perfectly (SR-N58/NHTSA 13V-483). It was a good assumption that this was the problem, so we decided to continue on to Seattle at a reduced speed to take it to the Jeep dealership to have the recall checked out. I decided to get off the freeway and take an arterial. At the bottom of that exit, there is a roundabout. As expected, all faults reappeared halfway through the roundabout (left hand turn), so we continued on until we could pull of the road to turn the engine off and restart to limp our way in. Unfortunately, where we pulled off there was an incline leaning right, which simulates the forces of a left hand turn, so this time, the car would not start after being turned off. In fact, you really couldn’t say that the car actually turned off. The engine could be turned off, but the ignition (accessories) really didn’t turn off. So we had to call a tow truck to take us to the dealership.

The dealership pulled a long list a fault codes which included the Electronic Shift Module (ESM). Additionally, the ESM would not show up on their topology readout, so they concluded that it was a bad module and required replacing it before they would perform any other diagnostics. Before doing that, I demanded that they check the recall notice even though my VIN was not included. After all, the recall was merely the tightening of an alternator ground wire and updating the software on two modules, so no big deal. They said they checked this out and the wire was good and the software up to date. Even though the mechanic agreed that there was clearly a CAN Bus issue, they wouldn’t proceed with that until the module, at $1,000, was replaced.

After the ESM was replaced, the dealership said that it now showed up on the topology report, but the original failure modes could still be reproduced by taking a left hand turn of sufficient speed, but the shifting and transmission were good to go. In discussions with the dealership’s mechanic, he didn’t know what to look for next, so I decided to take the car and drive it for a few days to hopefully gain some additional insight into the problem. The problem did reoccur in the first roundabout I came to, so I immediately took the car to my regular mechanic to get the service engine light fault codes recorded. They were:

U0101 Cosy Comm w-TCM
U0001 Hi Spd CAN Comm Bus
We cleared the fault register and I continued on to observe more behavior.

The next day, the same problem occurred, only more serious this time, and included the new ESM. This time, in addition to all the other failure indications of multiple warning lights, various system service notifications (specifically the gear shifter), the vehicle now had the additional behavior of not staying in gear. Speaking only of the gear shift issue, previously if the fault occurred the service gear shift indication would come on, the gear handle lights would blink on and off and the vehicle would go into a mode where I would have to turn the ignition off in order for it to be placed in park. In other words, the transmission would not move out of drive with the vehicle stopped until the ignition was turned off. In this new instance, all of those behaviors were again present, however this time, upon restarting the vehicle, which before would allow it to be driven again, upon putting it in drive, as soon as the vehicle started to move forward, it would immediately pop out of drive into neutral as indicated by the behavior of the vehicle and the indication on the gear shift handle.

It was an embarrassing experience limping the car back again to the dealership stopping and starting multiple times while holding up traffic. At the dealership, I insisted that before they perform any other diagnostics, they first needed to prove to me that the new ESM was still good since it clearly wasn’t working. After a few days, they called and told me that it checked out based on the following criteria:
  • Power & ground okay
  • Registered as present on topology report
  • CAN Bus voltages within tolerance
  • No functional bench testing possible.
Based on this, I was more convinced than ever that the original ESM probably wasn’t bad in the first place, so now the Jeep is at my regular mechanic.


If you have any insight into this that I can pass on to my mechanic, I would really appreciate your opinion.
 
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