TCM write error

[Executor999]

All,
Everything with the G8 is done except the tuning. We are having issues with uploading a TCM file to the transmission. For some reason it halted after over 50% was written.

I just remembered that I still have the VMS TCM tune in place and forgot to return it to stock before getting it tuned locally. I've contacted VMS directly but does anyone know offhand if a locked TCM tune would cause a write error? Can it be erased or reflashed with a Tech II without using VMS's software and cable to upload the stock TCM file?

Thanks in advance!

[Muff Daddy]

What are you trying to tune with? When I use hptuners that happens once in awhile. All you need to do is disconnect the battery for 10 minutes then re connect or you can pull the tcm relay under the hood and then put it back in after a couple of minutes.

[Executor999]

Yes, it is HPTuners. I'll give the tech your suggestions. Thanks.

[Muff Daddy]

It should be throwing a code. Also if he watches the screen real close when he tells it to write he will notice that no serial number pops up on the top of the screen next to the letters tcm. if its connecting properly a number will show up there just like it does for the pcm. Clearing the code via hptuners wont help he has to actually do one of the two things I listed above.

[Executor999]

Yes it is throwing a code. I'll let him know. Thx again.

[MANOFSTEEL69]

The Vector and Livernois tunes have to have the TCMs unlocked by them I believe. HP Tuners can not crack that. I made the mistake of going with the Livernois one and wasn't made aware at the time that is was now locked up. So, I will have to go back up to Livernois to have that undone, and my original file put back in so that I can use HP Tuners software.

[Muff Daddy]

I have had the exact error happen on 3 seperate g8's at random times now. I wouldn't chalk it up to the vms tune until he has tried my above suggestions. One day it will flash fine, the next day I end up pulling the relay to reset the code.

[Executor999]

The weird thing is, if I understand the tech correctly, he was able to erase the TCM that was there but when he uploaded the HPT TCM file it stopped with an error after halfway through the process. The car starts but there is a check engine light for obvious reasons, the entire TCM file wasn't uploaded.

[wreckwriter]

Generally the ECM is locked, TCM not locked with Vector. Pull the TCM fuse in the under-hood fuse box for a minute or 2 then reset it and retry.

[Muff Daddy]

The weird thing is, if I understand the tech correctly, he was able to erase the TCM that was there but when he uploaded the HPT TCM file it stopped with an error after halfway through the process. The car starts but there is a check engine light for obvious reasons, the entire TCM file wasn't uploaded.

yes because the code you are getting is a tcm communication error. have him look for the numbers I told you about. I banged my head for about an hour before figuring out what was going on. I'm pretty confident that you are experiencing the same issue.

[Executor999]

Thanks everyone for replying so quickly. Thomas reflashed the TCM with his Tech II and then uploaded both the ECM and TCM files from HPT so we are good to go!

[GeoffA]

I'm bumping this thread because this happened to me recently. Although I wasn't loading a tune I was checking one with my HPT. After I was done reading the car we too got an ABS fault and a TCM comm error. Not knowing that just reading the tune would have done this (cause it didn't to mine) I was pissed and embarresed being this was the first car other than my own that I read.

We didn't know about pulling the cable, we didn't have any tools where we were either, so we ended up clearing the code and re-flashing his car with his hand held.

Searching for this on HPT shows that this is quite common for the 6L80e's to lose TCM communication which I find odd and hope they can fix the issue.

[minytrker]

I have had it happen with both EFI and HPT on G8's and also new camaro's. I havent had it happen with EFI in a pretty good while, I think they fixed it with an update. The first time I had it happen I was at the track and I was loading my trans tune when it froze. I had to ask around to find some tools to un-hook the batt, I didnt know about the relay at the time. My wife wasnt to happy, she was freaking out thinking we were going to have to get the car towed, lol.