HELP Programming issue

[TBMSport]

:help2: The dealer is programming the TCM in the truck and it is refusing to take. The tech is explaining that the GM computer website is pulling up the truck's ECM and rejecting the VIN being downloaded into the TCM. He cannot 'build' the TCM VIN because of this.

Any ideas on how to wipe the TCM clean and make it ignore the ECM VIN?

[TBMSport]

Perhaps more specifically...can anyone explain how the TCM to ECM 'rewrite' process works?

[Taz]

Sorry ... not 100% clear on the problem, and therefore possible solutions. Would rewriting the VIN in the ECM and / or TCM to the required make / model appease the dealer ? If so, this is easy to do.


Regards,
Taz

[Taz]

Or do you mean the CVN / Checksum data ? See thread below for more info on those ...

http://forum.efilive.com/showthread.php?11715-2010-Camaro-ECM-Flash-Counter&highlight=cvn

Regards,
Taz

[TBMSport]

The problem is the TCM is not engaging ANY gears. There is communication with both, but as the E67 ECM OS isn't normally compatible with the T43 OS, we're attempting to rebuild the T43 with a VIN that has a T43. The technician is stating that no matter what, the TCM keeps pulling up the ECM's VIN and not the one he is manually overriding. Is it he doesn't know what he's doing or is there a special procedure?

[Taz]

Do mainly Gen IIIs ... Gen IVs are a little out of my "comfort" zone ! You can program the ECM and TCM with the same VIN - EFILive does really care what the VIN is (except for the scanner perhaps). So, find a VIN that you think will work for this issue, and enter it in the ECM and TCM - that way no matter what the technician scans, the VIN you want will be "found".

Once you have finished, then you can put the VIN back to what you want.

Regards,
Taz

[TBMSport]

I'm not using EFILive. The truck is at the dealership and they are using GM scan tools.

[Taz]

OK .. don't know your relationship with the dealer, or if they could / would temporarily change VINs for you to allow software to load .. will leave that with you.

If you end up coming back another day ... can enter the VIN that you believe will work using EFILive in both the ECM & TCM. I'm not sure this will overcome the issue the dealership is having, but it's one more variable that you can eliminate.

Regards,
Taz

[ScarabEpic22]

Jesse, the VIN is irrelevant except when scanning enhanced PIDs. Ive heard the Tech II uses it to pull the latest OS from the GM servers. Ive put a random VIN in my TCM for kicks, truck started and drove exactly as before. As for the 'TCM to ECM rewrite', that would be impossible as the 2 modules have very different hardware and will not accept a tune from a non-compatible module. But if you mean how the ECM uses the tables in the TCM, Im honestly not sure. The trick here is going to be finding a TCM OS that will properly communicate the gear status and everything to the ECM.

[TBMSport]

I think I figured out the problem. The situation was the already programmed TCM from another used tranny was put in my truck without reflashing and went into LIMP MODE (Park Reverse Neutral 3rd). Once we reflashed it, all gears were lost. I thought it was a VIN issue. It then hit me that the Park/Neutral wire was not connected to the ECM. Therefore I believe that even though we did a swap from one truck to another without a reflash, the memory in the TCM already established reference points for gear engagement. In the reflash, that memory was wiped clean and therefore has no reference whatsoever, so it's simply not engaging gears to be safe....hence go past LIMP MODE and straight to total shut down.

[gmh308]

Do you know absolutely that you have the right model year TCM for the trans? Flashing in an earlier OS to a '10 TCM and vice versa can cause terminal problems...

Normally with TIS the ability exists to program a TCM without ECM attached. The relevant OS is copied to the tech II based on punched in VIN and then the TCM flashed standalone.

[TBMSport]

We're using an '08 TCM being flashed with an '08 VIN. I have no clue exactly what his procedure is. I don't know how he can program the TCM in the vehicle without the ECM due to the harness layout.

[ChipsByAl]

He can remove the ECM, jumper the hi speed LAN terminals back to each other and attempt to program with the ECM out of the loop. The concern will likely be the BCM though, it also stores the VIN and may inhibit communication between the ECM and TCM.
AL

[TBMSport]

Ahhh. I think we've determined the last hurdle. Unfortunately, the original VIN that worked and that was put into the old TCM was not recorded before we fried the TCM. So we're stumbling around with various VIN's and finding out that some VINs Calibration ID's are very picky.

At this point I'm happy to have Limp Mode back and my PRNDL finally working. I believe at this point the issue seems to be one main problem. We used an '08 TCM VIN Cal ID with an '07 ECM. I know GM made subtle, yet significant changes to there '08-'10 calibrations to tighten down on various aftermarket tuning. So, not knowing where these changes occurred during production runs and/or which vehicles were affected, I believe it would be best to go back to an '07 TCM VIN Cal ID...when programs were less fussy.

They won't have a chance to revisit it until Wed/Thurs.

[joecar]

Sounds like you're having too much fun...:doh2::doh2::doh2::doh2:

[TBMSport]

:hihi:oh yeah!!! :fluffy: lol The only reason I push through and justify it all is because I know it will save those who follow with their own unique projects sooooooooo much money and hassle later.

[ScarabEpic22]

OK glad you're at least making headway on tracking it down. This is in your 5.3 right? Any way you could switch to an 07 T43 OS or switch your ECM to an 08?

[gmh308]

What OS are you running in the TCM?

[TBMSport]

Yup, it's the 5.3L. I thought about upping the '07 ECM OS to an '08, but then I'd have to change the VIN to an '08 and then I remembered that there were changes each model year 06-08 regarding how the ECM monitored and controlled the fan clutch. That would require the patch to keep the MIL from coming on. Plus, I don't want to 'cheat'. I'd rather find a solution that allows the ECM parameters to remain stock and match the vehicle's original specs. You change one thing here and sooner or later you'll find something else changed over there, ya know?

The TCM is currently running a 24239353 OS. It's not only triggering the check engine MIL, but also the powertrain/transfer case MIL. I'm pretty confident this is the problem and a result of GM making a more stringent security checking feature in the program...via checksums, etc.

[gmh308]

Ok so you are running the generic '07 TCM OS. What is the ECM OS? And what are the calibrations of each from? If you are running the stock TB 4x4 ECM cal, then it sounds like it is missing transfer case controller messages.

Might help if you outline your setup in a little more detail :).

[TBMSport]

No, I'm running the original '07 ECM OS and an '07 XLR-V TCM. We tried '08 Denali, Escalade, and 2500 Suburban. None worked. So we're experimenting with various model years and trucks OS's. I think the key is to keep TCM and ECM model years and vehicle drivetrain platforms the same.

[ScarabEpic22]

In an ideal world yes, it would be awesome to use the same platform for both ECM and TCM however the TrailBlazer guys are screwed as a 6spd was never a factory option. Too bad the T43 probably isnt like the LS1 PCM where EFILive added the platform options section to control the differences across the different models. Lets you change the alternator output on a V6 Blazer with a 0411 PCM swap running a Camaro OS for example.

The 07 -> 08 fan clutch difference is the 07 is ECM controlled, the 08-09s arent. Wouldnt throw a light going 07 engine -> 08 OS but going 08 enging -> 07 OS would.

Its a shame we dont know more about how the different TCM OSs interact with their ECM OS counterparts. Wish GM would have made it consistent, but noooo they have to make each one unique and cause this frustrating issue...grr.