I have a 2008 H3 with 120K km on the clock, 4 days ago after a 500 km drive I got a transmission failure message after stopping for 10 minutes or so and trying to restart. 1st gear indicated on the dash and the car stuck in park. Unfortunately I was in the port leaving France for UK and had passed passport control. After some research I found the shift lock override and the next morning was able to get the car out of the port. I started the car and put in gear, then the fault cleared, the transmission indicated drive and all was fine for 10 minutes until I switched off and restarted, when the fault came back.
What I am finding is after leaving the vehicle to cool for a good while (30 minutes to an hour), I can start the car, use to bypass on the shift lock to get the car in gear and the fault will clear, and stay clear until I stop and restart. The other night I drove from Portsmouth to oxford (about 2 hrs) with no issue but once I turned off and tried to restart, the issue was back. Diagnostics has given U0101 fault which is TCM failing to communicate.
I have seen posts about loose pins and damaged 12v supply causing U0101. My suspicion (given the predictability of failure) is this is probably a component overheating in the TCM rather than a cable/connection problem. Any thoughts would be appreciated.

 

Welcome to HF. I MOVED this for you as any/all H3 questions go in the H3 section. Drivetrain has been an archive no post area for years. Gotta LOOK before you post...

Anyways, TCM failures are far and few between, pretty rare. What is mot likely is harness and connector corrosion as your H3 is OLD, as in 17 YEARS OLD. That does means corrosion and compromise in harness, connectors and grounds.

Are you still trying to use the OEM Battery Terminal Connectors? If so, replace with a quality aftermarket set like Stingers or your favorite brand. The #1 mod to be done to very H3/H3T. Known electrical issue failure point. You have an electrical issue, it could be a bad TCM, but before sourcing one, having it programmed to your vehicle (got no idea what you would pay for that over there) I would trace the harness to it, look for fraying, rubbing, cracking, disconnect it, spray connections with CRC Electronics cleaner and reconnect after dry, and check that the fuse for that circuit is clean and corrosion free and/clean it as well.

Good luck. Let us know where this issue goes.

 

Doc Olds, thanks for putting the post in the correct location and your advice well received. I have taken a brief look at the loom and the connector to the TCM as I had read of one instance where a cable had been damaged by the cable tie on the connector. I have managed to establish that the permanent feed, ignition feed and ground are good at the TCM, also I am getting 12v on a number of sensor feeds, although didn't have time to check which ones, Checked the fuses also. Since the first post my conviction that the problem resolved itself after a period of cooling has been proved wrong, it held good for a few days but then I lost the TCM permanently on the drive back from North UK to SW France. Car is now parked up for a few months while I am away with work. I have seen TCM units on sale on a certain auction sale and these are offered pre-programmed, even with the cost of postage from the US to EU they are not too expensive so will take a gamble on one on the chane it may save me several days tracing a fault in the loom, will also take your advice with the post terminals. The only other time I had a problem with this car since new, was not starting due to a poor battery connection - quickly fixed once identified.

 

No doubt any electronic part can fail so it is quite possible your TCM died. I have seen far more BCMs and PCMs short than I have TCMs, but you are onto a good plan.

Please circle back around and let us know what happens when you can get to it.

 

OK 3 months later and I am back home with a couple of weeks to try and sort out the problem. Since posting last, I have been pondering could this be a poor connection, the expansion tank has lost fluid since this car was new and when I moved the tank to get access to the TCM last, I noticed there was quite a bit of moisture below the tank, that got me wondering if the PCM contacts which are directly behind the tank could be the problem. Today I put a diagnostics scanner on the the truck and got a fault reported on the PCM not communicating with the TCM, the TCM showed OK. I also had a brake system warning, I tried to clear the faults from the scanner, the brake system fault cleared but returned after stating the engine, however the ECM fault does not clear. I tried disconnecting and reconnecting the PCM to see if it could be some oxidation on the terminals but made no difference and the pins look spotless. I am going to try and spend the afternoon tomorrow checking earth connections. I need to get some electronics cleaner ordered so I can go through the connectors per Doc Olds advice. Next job I presume will be to try and check the circuits between the PCM and TCM, fortunately they are in close proximity, so I am hoping I can identify the various connected pins from the wiring diagram. Another thing I have noticed is the engine seems to run a little rough since this issue started, this has go me wondering if it could be the PCM rather than the TCM that is at fault ( assuming the wiring and connectors are OK).

 

Welcome back. Keep after it now that you have some time.

Good luck.

 

This afternoon I spent a couple of hours checking fuses and codes again. My diagnostics reader decided to throw a wobbler meaning I had to spend 45 minutes reloading the software, but after that ran the scan a few times, initially I had been getting a fault on the PCM(ECU) that communication to the TCM was lost, that then developed into PCM not fitted, that seems to have been that I hadn't pushed the connector lever back home on the TCM, having made sure connector to TCM was firmly in place, the ECU code cleared.
I managed to locate the electronics connector to the auto gearbox, that appears to have been an issue on the H2, gave it a wriggle about, but will need to get the car over the pit to get better access to remove and clean the connections, tomorrow my pit is booked out to friend wanting to replace diff pinion oil seal on his MG, so will need to get that out of the way first.
I am now getting ECU OK, TCM not fitted and a data fault on the brake control unit (presumably arising since the system cannot find the TCM)
I think tomorrow I will start opening up the loom to look for damage to cables, I read somewhere someone having the same fault I have on a 2010 model due to 12v feed to the TCM being damaged.

 

Update,
Have checked a few of the cables to the TCM that I can easily identify.
Permanent and ignition 12v feeds to the TCM OK, TCM earth OK, HI SPD Serial data bus + & - between TCM and ECU both OK.
Diagnostics telling me the TCM is not fitted, and ECU has lost communication with the TCM.
Given I know there is power to the TCM and the Data bus between ECU and TCM is OK, is it reasonable to assume that the TCM has malfunctioned or do I need to start chasing down the various signal feeds?
Any thoughts appreciated
The TCM is not too expensive to replace, however postage to France from the USA is a few weeks and I am heading away for work again in a weeks time.

 

3 months on, and I am back from working away.
Problem solved.
Replacement TCM programmed to the VIN has got me back up and running.
Thanks for the pointers an checking circuits etc.

 

Wow thanks for the follow up.