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Discussion Starter #1
Hello,

I have a brand new JLU rubicon and every time I go off road (just driving on a bumpy forest road, nothing crazy), my car starts acting up. The transmission shifts to neutral momentarily and then back, often a message "AutoPark Disabled" flashes on the dashboard.... Once I got a code "U0101 - lost communication with TCM" and I had to power cycle the ECM to get the jeep to start again...
I even filmed one trip to prove it to my dealer (who has not been very helpful - their position was hat if they can't reproduce it in the garage, they can't fix it). They agreed to send the link to the video to the FCA engineers but it's been almost a month and there's still no answer (and no new views on the video on YouTube :-( ).
I have a strong suspicion that it's either the cabling or the TCM that has some loose connection inside causing lost comm and consequently the TCM shifts to neutral as a safety precaution. I was asking the dealer if they could just swap the TCM quickly and let me go for a short ride in the forest - their response was that hye can't just be swapping part willy-nilly.... Very frustrating.

I wanted to have a look at the TCM myself but I can't find much info anywhere about JLs and TCMs - I think I know which module is it under the steering wheel but have no idea how to get it out (it's kinda hard to get to and it looks different than the JK that I saw on YouTube)....

Anyone with any insight or thoughts? Instructions on how to remove the TCM on JL would be great... I am desperate, if I have to buy another TCM, I will....

here's the video I filmed:

Thanks
 

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Welcome from Arizona.
 

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Take a tech for a ride through the forest to try and reproduce the issue.
 

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Discussion Starter #5
Take a tech for a ride through the forest to try and reproduce the issue.
I suggested that. Covid 19 (they are not comfortable).... So they took my car alone. According to them - no issues. Then I picked up the car (same day) and went out (frankly I was hoping that they fixed the issue just by looking at the connectors, etc.). That's when I filmed that video - I encountered 7 issue on 15km drive. The conclusion is that the dealer must have lied when they told me they went out.... I can;t see how else would they not see it.
 

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Fuses securely mounted in their clips?
Seat belt buckled?
Driver door closed securely?
Door removal electric harness disconnect/plug connected securely?
TAZER anomalies?

Good luck tracking it down.
 

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I can't comment directly as I do not own a JLU, have a JKU Rubicon Recon. I might suggest checking on the Ram truck or Ram Rebel forums. They use the same auto trans as the JLU although I imagine the shift maps are different. The 8 speed auto has been in the Rams a lot longer than the JLU and maybe someone on those forums will chime in. I have been spending some time on a few of the Ram forums as I am considering the purchase of a Rebel or Power Wagon but I don't recall reading anything about a tranny issue like you describe.
 

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As mentioned above, check your fuses and relays in the box behind the battery. I read about this on another site. When I checked mine yesterday, most relays weren’t fully seated. Some I could actually see the prongs on. He reported that several electrical gremlins went away. I had a problem with my driver door window not going down on the first touch. Yesteday and today it worked fine.
 

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Discussion Starter #9
Hi guys,

Thanks for the suggestions. I have tried all these. So did the dealership (they even opened all connectors and checked for pushed-in pins, etc.). The issue seems to be more tricky. I think the logical thing is to try to replace the TCM but for some reason, the dealer is refusing to do that... Does anyone know if the TCM could be swapped? Does it need to be programmed with the VIN? I found after-market TCMs for JKs but nothing for JLs.

Thanks
Peter
 

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Have you tried shifting the transfer case to see if there is an intermittent connection? The warning dialog AutoPark Disabled would normally appear when shifting into 4Lo, so perhaps the issue is related to an intermittent connection related to the transfer case settings.

Watching the video, it seems that you are also having symptoms of AutoPark actually kicking in. In other words, while it is obvious that the AutoPark Disabled dialog appears there may also be times when it is enabled. For instance, when the transmission shifts to neutral and the engine revs. Is it possible that the driver is bouncing in the seat and the seat occupancy sensor is detecting an absence of someone in the driver seat? Have the connections to the seat sensor been checked etc.?

Good luck.
 

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Discussion Starter #11
Hi Willy,

thanks for taking the time to look at this.
I had the same thought about the transfer case but I encountered this issue while in 4H (most of the time), 4L sometimes and even 2H. Once actually on a normal city road.
The issue does not seem to be related to the "intensity" of the vibrations and much as how "sustained" they are. i.e. it never happened after hitting a big pothole or a bump but it almost always happens after driving a minute or so on a shaky road.... I'm an electronic engineer and this is very consistent with how CAN bus handles errors. If the controller encounteres certain number of corrupted packets in a time frame, it goes into an error mode. So a single glitch will not even be visible but many glitches will cause a shutdown.
I have a feeling that a faulty mechanical switch in the transfer case would make the issues more dependent on the intensity of the vibrations... and then, there's the "U0101 - lost communication with TCM" and the fact that several times the TCM clearly shifted to neutral and back.
In fact, I think that both the ECM and TCM are detecting the comm failures - ECM shows that message and TCM shifts to neutral as a failsafe. TCM probably has a more generous timeout to shift so it happens less frequently than the message.

So in my mind everything points to the TCM comm. Question is what can I do about it (if anything) in a situation when FCA and the dealership are refusing to take action...

Peter


Have you tried shifting the transfer case to see if there is an intermittent connection? The warning dialog AutoPark Disabled would normally appear when shifting into 4Lo, so perhaps the issue is related to an intermittent connection related to the transfer case settings.

Watching the video, it seems that you are also having symptoms of AutoPark actually kicking in. In other words, while it is obvious that the AutoPark Disabled dialog appears there may also be times when it is enabled. For instance, when the transmission shifts to neutral and the engine revs. Is it possible that the driver is bouncing in the seat and the seat occupancy sensor is detecting an absence of someone in the driver seat? Have the connections to the seat sensor been checked etc.?

Good luck.
 

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Hi,
I am just an electronics technician, but I appreciate everything you have explained. One thing I would consider is that it seems unlikely that an integrated circuit has an vibration induced internal fault resulting in the loss of packets, where as it seems highly likely that some discrete connection does. The point being, you may not need a fresh TCM to test if a removal and replacement will be helpful. I will admit that I don't know how to swap out a TCM on a Wrangler JL, but if you intend to do so after you find a replacement part, I would suggest that you go ahead and try it with the existing part.

I am very curious to learn how you solve this.

It seems like you are capable and qualified to work through the details, but I hope you find a dealer that will help you with the diagnosis and fix as the situation certainly seems to warrant the full support of FCA and its dealer network.

Good luck!.
 

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Discussion Starter #13
Thanks Willy,

I agree. It's unlikely that a circuit has an internal flaw (although I have seen some "shit" :). But there could be a cold contact inside the module on the PCB etc.... I would definitely like to have a look at that module - unless it's all potted in epoxy.

On another note - I am really disappointed in the level of support I'm getting from FCA. This is a fully loaded Rubicon I just bought and I have to beg them for every bit of attention (of which I got very little). In any other industry if I but a $50k piece of equipment from you, I would expect at least some support.

I will post here when I make any progress...

Peter


Hi,
I am just an electronics technician, but I appreciate everything you have explained. One thing I would consider is that it seems unlikely that an integrated circuit has an vibration induced internal fault resulting in the loss of packets, where as it seems highly likely that some discrete connection does. The point being, you may not need a fresh TCM to test if a removal and replacement will be helpful. I will admit that I don't know how to swap out a TCM on a Wrangler JL, but if you intend to do so after you find a replacement part, I would suggest that you go ahead and try it with the existing part.

I am very curious to learn how you solve this.

It seems like you are capable and qualified to work through the details, but I hope you find a dealer that will help you with the diagnosis and fix as the situation certainly seems to warrant the full support of FCA and its dealer network.

Good luck!.
 
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