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U0101 code - Lost Communication with TCM Help

59K views 42 replies 11 participants last post by  theheder  
#1 ·
After replacing my Alky Control pump in the trunk this afternoon and testing it is working as expected in the garage. I shut the car off and went inside to wash up / change clothes for a test ride to the grocery store.

Come back out and start it back up then I see the "Service stabilitrak / traction control off" message and the CEL on. Connected HPtuners and pulled code U0101 - lost communication with TCM. Tried removing the battery for 10 minutes and while I was checking the connections / grounds but really didn't find anything. Just putted around the driveway to see how it acted but shifts really hard 1-2 so I pulled it back in the garage. I checked a handful of what fuses that I thought maybe of interest but didn't find any blow ones. Everything else works normally.

I gave up for the night and grabbed a cold one and came here. I searched this forum and see that there was some mention of checking the Magnetic ride sensors. I visually checked the rear and front ones but I saw nothing obvious. Also saw some threads about BCM changes but didn't really match my symptoms




Any suggestions?


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#2 ·
Cleaned up the battery terminals and the ground in the trunk.

All codes and dash lights cleared up. All good after a 20 mile drive.


Puzzled but glad it was an easy fix.



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#3 ·
This happened to me again at lunch time today. Drove fine to work and out to lunch, but when I go to head back to work after lunch I go the same messages - Service stabilitrak / traction control off / Parking brake light on.

I disconnected the battery for about 10 minutes but that didn't resolve it. I had to get back for a meeting, so I drove it on a back road stuck in what seemed to be 3rd gear (40mph @3k rpm) and coasting in neutral when I could.

For no particular reason I heard the door locks activate and the dash lights went out then everything was back to normal....... IDK what is going on........ My gut says electrical issue, so I will dig around and see what I can find.
 
#4 ·
How old is the battery? Do you have anything plugged in the OBD, sometimes my dashlogic screws with the stabilitrak and I get the warnings.
 
#10 ·
Fwiw, when my Dashlogic would cause this the DIC warning would go away immediately after i pulled it out of the port.
 
#11 ·
This damn U0101 came back today while I was working with HPTuners and I can't get it to go away. Communication with the ECM works fine.

I unplugged everything from the ODBII port, disconnected the battery for 1/2 hour, checked the plug / wires / pins / connector in the trans and blew some air in them to remove any possible debris, cleaned the battery posts and trunk ground, cleared the codes and it comes back immediately when I turn the key on.

"Stabilitrac Off"
"Parking assist Off"
"Service Stabilitrac"
"Service Tire Monitor System"
"Service Traction Control"

Not sure what else I could try to get this bitch to recognize the TCM at all.


Any suggestions or recommendations are welcome!
 
#16 ·
Before pulling it out I am going to try and isolate the problem by test connecting another known good TCM to see if it talks.

Running down to Rick Crawford's place to pick it up tonight
 
#17 ·
Any luck here? I had this issue in the car my drivetrain came from, never could get the car to even start. Not as much on these cars, but in other places I have read where people had issues with broken wires(generally grounds) somewhere in the harness, not even necessarily showing at times. Sucks because it is extremely hard to find. If I still have the problem when I Get my car going my plan is to use my ohm meter and check resistance throughout the harness.
 
#18 ·
I have also heard about wiring, ground, and intermittent CAN / ODBII port issues. I have looked for them more times than I would like to share.

Faulty TCM is the next suspect. Hopefully I'll know more tomorrow when I get a chance to test with another TCM.
 
#19 ·
Damn it.

I tried 4 different TCMs with no change in behavior.

I went back and checked / tightened every ground I could think of:

Trunk by the battery
Back of both heads
Under the intake
Behind the passenger headlight
Top strap on top of the passenger tire well
Driver's side kick panel
Under the rear seat on the Fore fuel system
Trunk around the Bose amp and Alky set up


I strongly dislike this car at the moment.
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#20 ·
#29 · (Edited)
Thanks! I'm no wiring fan at all. I'll give that a try.

I found it interesting that when I pulled back the plastic wire loom and wads of black tape on the TCM connector and back of the OBDII port, I can see small pin insert holes in the wires that I am interested in (Tan and tan with black stripe). I am guessing those were from testing.

Someone else has been in here before.......

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#30 · (Edited)
Poking around some more with the wiring.

I see that the wires of interest are tightly wound. Like some one put them in a drill and twisted them. Wondering if that is a problem?

I've seen that on audio equipment like what I have in the trunk for the extra amp.

I'm tempted to pull it out and unwind it.




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#32 ·
If the wires look suspect it may be a fair place to look. When I disassembled my harness I don't recall seeing any like that or in a factory "twisted pair" setup. Building on the above post, you could also throw a jump pack on the battery to make sure you're getting all you need. I had an 08 Ram 2500 cummins a couple years ago do something similar, ended up being a poor connection at the terminal on the drivers battery that was making the whole truck go limp. Wild because it was on a brand new battery, and I nearly had to bust the connector getting it tight enough to be happy, but it never happened again.