The stand alone TCCM 08 LMM, the last hurdle

Mogman

Member
May 3, 2020
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Papalote, TX
OK so it seems I am getting most of the problems squared away on my LMM/Humvee conversion, the last one is the TCCM, I have replaced the motor.
From what I have read the motor "self learns" every time the ign is turned on.

When the ign. is switched on I see all the position lights light up for a couple of seconds then nothing, no lights or action after that.

Someone that builds a stand alone setup for the Duramax (that does not work on the LMM) says on the LMM the switch must be calibrated with a scan tool or dealer tool.

Can anyone confirm this? if so can it be done with EFILive?

THANKS!!
 

Cougar281

Well-known member
Sep 11, 2006
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St Louis, MO
I Believe the TCCM on the LMM does need to run through a relearn procedure under some circumstances. I've had to do it once or twice on friends LMMs. In their case, I don't know what triggered it.

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Mogman

Member
May 3, 2020
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I Believe the TCCM on the LMM does need to run through a relearn procedure under some circumstances. I've had to do it once or twice on friends LMMs. In their case, I don't know what triggered it.

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How do you do a re-learn?
 

Mogman

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May 3, 2020
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Papalote, TX
I tried with the key on, twisting the switch past 4L and held for a minute but did not here the motors move.
Edit, I do not see any codes, even with the switch unplugged, I looked at the tune and do not see anything so I guess I need to tear down the dash again and look at the GMLAN connections, I was getting a code earlier, "fail to learn" which most posts say is a failed motor which I replaced, but I would expect the TCCM to complain that there was no switch..
 
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Mogman

Member
May 3, 2020
341
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Papalote, TX
Well I have just about run out of ideas, I have ohmed out the cables including the GMLAN and all look fine, I installed a new factory TCCM with the same part number that I took out of a sealed package and it will not do anything, not even light all the position lights when powered up, so I have a new switch, new motor and have tried a new TCCM, I marked and connected the old motor and it does not appear to try and move, guess I will try removing the new motor and see if it tries to move next.
The front servo motor which is connected but of course not doing anything (no front GM diff) does cycle when powered up.
 

Cougar281

Well-known member
Sep 11, 2006
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St Louis, MO
I had never heard of the 'hold it past 4LO' to do the learn... I don't recall the exact symptoms or procedure, but I've done the relearn on two LMMs with my tech2.

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Mogman

Member
May 3, 2020
341
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Papalote, TX
Thanks guys, I see a "GM TECH 2 scanner" for for less than $100, is that all I would need?
Actually that looks like an unreliable source, looks like $250 or so from recognizable sources
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
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Thanks guys, I see a "GM TECH 2 scanner" for for less than $100, is that all I would need?
Actually that looks like an unreliable source, looks like $250 or so from recognizable sources

maybe. those chinese units sometimes work awesome, sometimes dont do shit. if you can easily return it, you can give it a shot
 
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Mogman

Member
May 3, 2020
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I did find a cheap one that the guy sent these screen shots, he does offer free returns, may take a shot at this one...
1.JPG
2.JPG
One would think one would be available for rent, considering I hope to only need it once.
 

Mogman

Member
May 3, 2020
341
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Papalote, TX
I swapped in the TCCM from my 08 1 ton and it appears I have 2H, 4H and 4L YEAH!!
I can read but have not been able to reset the old TCCM with the cheapo scan tool I bought, the "NIP" TCCM I bought will not read or do anything.
FWD is not too important right now in the 1 ton...
 

DAVe3283

Heavy & Slow
Sep 3, 2009
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Boise, ID, USA
It isn't uncommon for new GM modules to come unprogrammed. If you could get a dealer to flash the "new" module, it may we'll work.

Sent from my FlashScan V2 using Tapatalk
 

Mogman

Member
May 3, 2020
341
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Papalote, TX
I was able to do the relearn by twisting the switch to the neutral request position with the truck in neutral and in the ign. switch in the ACC position. I am still curious how long the TCCM has to sit without battery before the learn is lost, I had the one out of my one ton for only a few minutes and it was fine, the donor truck in which the TCCM that needed to be "relearned" sat for many months with the battery cables cut by the fire dept.

DAVe3283 seems to be right on the money with the factory new module as it will not even boot (all lights flash on together when the ign. is tuned on) indicating it has no program, dealer wants $144 to flash it, not a terribly high charge.
 

Coryend

New member
May 21, 2023
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Hey did you run a bcm in your swap? I can’t get my tccm to connect at all. I can get it to Shift hi and 2 hi thanks it