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In this video I have a look at a 2009 GMC 2500 that is exhibiting some really strange transmission issues. It only seems to act up once the TCM (mounted on radiator shroud) gets hot. We call it "hot soaking." It sets tons of erroneous codes that just don't make sense. I try to duplicate the symptoms in this video. These are a very common failure on these trucks. -Enjoy!
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49 thoughts on “Chevy duramax w/ allison trans: tcm failure”
  1. Avataaar/Circle Created with python_avatars Doug Kelley says:

    Thanks for bald eagle shot

  2. Avataaar/Circle Created with python_avatars Diamond Press Co says:

    had same issue with avalanche my way of testing is hot soak and pour cold water on modiule

  3. Avataaar/Circle Created with python_avatars Ireland 1968 says:

    Great video 👍

  4. Avataaar/Circle Created with python_avatars John Godley says:

    Thanks for videos. You do an excellent job explaining your work

  5. Avataaar/Circle Created with python_avatars Chad Winget says:

    Wanted to start by saying I absolutely love all your videos! I wish your shop was closer to me cuz you would be one of the very few I would trust my vehicle with.
    I am having basically the same issue with my TCM with my 2002 Silverado with Allison transmission and I was trying to follow the steps you had taken but cannot find the mail plug pen diagram online where it unplugs from the TCM so I can check hots and grounds. I'm sure you're always busy but thought I would ask if you got a chance would you mind sending me a diagram for that. My truck is a 2002 Chevy Silverado 2500 HD 8.1 with Allison transmission

  6. Avataaar/Circle Created with python_avatars dakota manor says:

    I got a 2009 gmc lmm duramax. I put a new engine in it Bc the crank broke. It runs and drives but it doesn’t drive but 15-20 mph and it’ll read “engine power is reduced” on the cluster. It does that when it needs to shift to go into second gear. It’s full on trans fluid. What is causing this?

  7. Avataaar/Circle Created with python_avatars double K says:

    Thanks for sharing your expertise

  8. Avataaar/Circle Created with python_avatars Cindy Felisko says:

    Here I am sitting in TX with my Vermont 2012 Chevy 4500… trying to see how to reset computer after battery disconnect, computer not communicating with tcm….n I get a video from Champlain N.Y. go figure if only I were home I'd know who to go see….. hey thanks for the eagle viewing….. sure make me miss home

  9. Avataaar/Circle Created with python_avatars Christopher Gonzales says:

    My lbz shuts off while driving or at park. And range shift inhibited comes on the cluster. All fuses and relays are new. Could a new tcm solve this?

  10. Avataaar/Circle Created with python_avatars Vic-Ohio-A says:

    Funny, I am a mobile diagnostician in training and have a 2010 Chevy 3500HD w/ Allison 1000 had the PO708 code, and would not move in any gear, went to clear code, no dice. I verified my PRNDL in scan tool everything good. Go and tap gingerly on TCM and go back to scan tool it clears code, now the truck goes in gear. Perfect, will check my powers and grounds, and call it from there, thank you sir!

  11. Avataaar/Circle Created with python_avatars Jackie Hayes. says:

    You just helped me,I can,t think you enough, send information, where I can purchase,s, that, program ain't,thanks again.😎😎🦅

  12. Avataaar/Circle Created with python_avatars Chris Haynes says:

    Mines popping up lost communication with tcm. Any ideas.

  13. Avataaar/Circle Created with python_avatars homesteading survival says:

    Got a 06 lbz clogged line messed up the converter rebuilt the tranny and added a trango Jr and new cooler drive hits hard reverse hits hard and sometimes acts like it come out of reverse and right back in and stays 1 to 2 and then 3rd gear hit hard and acted like it slipped a bit then p0700 code shut me down cleared the codes keep repeating that after about 7 short drives 1st to 2 and hit normal but when its third it throws p0700 code and shuts me down any ideas what it might be. Have not got it relearned yet or if that will help

  14. Avataaar/Circle Created with python_avatars John Dickerson says:

    I was wondering if you did a trans service as well.

  15. Avataaar/Circle Created with python_avatars James in the Engine The Mr. Bill says:

    You are the man you saved me so much money .thank you.

  16. Avataaar/Circle Created with python_avatars Bobby Martinez says:

    Quick question will a bad Tcm on a 08 Silverado with 5.3 cause no crank no start

  17. Avataaar/Circle Created with python_avatars Steve Luken says:

    Late to the party but had to say, if my mechanic told me "I think its the TCM but it wouldn't throw a code so I hammered it and torched it until it did. So I replaced it." I'd probably find a new mechanic. 😆

  18. Avataaar/Circle Created with python_avatars DormantIdeas NIQ says:

    how can I get a complete list of all the sensors and control modules on my 2010 Chevy Express Cutaway chassis 4500 with the 6.6 LGH DURAMAX with 2011 exhaust emissions level! yes, maybe weird but it is a 2010 on VIN but 2011 on emissions! All factory no mods. The upfitting is minibus (Arboc mobility)… making it my motorhome.

  19. Avataaar/Circle Created with python_avatars Chris Bayne says:

    If you get a chevy c6500 kodiak with 3126 truck gos to limp mode replaced speed sensor on tail shaft of trans and gas pedal sensor

  20. Avataaar/Circle Created with python_avatars John Morin says:

    Oh man that looks like quite a nightmaire with out those proper tools. great deductions WATSON

  21. Avataaar/Circle Created with python_avatars Barry McCarty says:

    Great video Eric, today my truck slammed in to 3rd gear when i was pulling my camper, and it will not come out of 3rd gear, but you can shift it to park,reverse low i will try it in the morning when it cools down. I have a 2015 GMC. Thanks for the vid.

  22. Avataaar/Circle Created with python_avatars Shaun Adams says:

    Maybe just charge for the hour and a go pro and they won't have to worry about it

  23. Avataaar/Circle Created with python_avatars Shaun Adams says:

    Or the torch love it keep them rolling

  24. Avataaar/Circle Created with python_avatars Shaun Adams says:

    Just need a bigger hammer

  25. Avataaar/Circle Created with python_avatars duramax4life says:

    People laugh at the claw hammer but the rubber oval handles or wooden handles work great for pushing the pistons back in ur calipers. I stick it in the caliper with the old pads and rotate it like an accentric and it pushes the pistons back in easy👌

  26. Avataaar/Circle Created with python_avatars TODOS POR EL CONGO USA. says:

    Where u buy this scanner?

  27. Avataaar/Circle Created with python_avatars Donald Rackley says:

    Great video Mr owe as always full specs

  28. Avataaar/Circle Created with python_avatars Nicholas Andre says:

    I know some GMs have solder joint problems. With my 2000 Sonoma it has it on the ABS module. The pads crack and every time you go over a bump at whatever temperature. All you have to do is crack it open and resolver the pin pads with some solder that isn’t garbage.

  29. Avataaar/Circle Created with python_avatars TowTruk 412 says:

    Can I bring my truck 4127089160

  30. Avataaar/Circle Created with python_avatars Rey Noyola says:

    Please what kind of scanner are you using for this problem please thanks

  31. Avataaar/Circle Created with python_avatars Juan Godínez says:

    Why wouldn't you just check the connecters?

  32. Avataaar/Circle Created with python_avatars Ralfie says:

    This reminds me of the old 1970’s Ford Duraspark modules. If it wouldn’t start, smack that module with a hammer and it would start every time until it went completely out and you had to replace it.

  33. Avataaar/Circle Created with python_avatars miguel favela says:

    Oh wow. I’m in Vegas and the shop is changing the p0708 sensor.
    But I only have 95 k miles. I wish I could have seen this before. I hope the problem gets fixed but from watching this I’m sure it most likely the tcm

  34. Avataaar/Circle Created with python_avatars Jorge Guzman says:

    What was the cost for this service?

  35. Avataaar/Circle Created with python_avatars Avery Alexander says:

    What a ridiculous place for a computer in a hot and wet engine compartment, everyone knows that heat and moisture is bad for computers.

  36. Avataaar/Circle Created with python_avatars kenneth bode says:

    you can find lots of stuff with a hammer

  37. Avataaar/Circle Created with python_avatars Carlos Gutierrez says:

    awesome video! my truck is in the shop right now the guys couldnt figure out why so many codes with 64k miles on it. my truck is doing everything the one you are working on is doing.

  38. Avataaar/Circle Created with python_avatars Robert Harrison says:

    Okay. Before any diagnosis of TCM of transmission. The first place to look is the wiring harness containing a hundred tiny wires tightly fitted over top any access to the lower part of the engine. What are the odds, some big fat arm pushed its way past the wiring harness and loosened just one of those tiny wires. If it did, your code reader is going to show failure of the communication between the TCM and the many, multiple, functions it communicates with every second. And, all it is, is a loose wire. I had a transmission shop tell me this repair would cost 1600.00 minimum and there would be no warranty. All it was, was a loose wire. Do you think the transmission shop knew the bad code was probably a loose wire? Of course. Do you think I would return to pick up my vehicle and the shop would say, hey good news it turns out all that was wrong was a loose wire and the bill is only 100.00? This is a warning to all the shops who think they can still dupe the customer. Be nice, be honest and you can have a good living. Be a creep and take advantage of vulnerable people, and it could be you asking me how much I want to make this go away. I was even offered a job. All it was was a loose wire. 😉

  39. Avataaar/Circle Created with python_avatars Bob Risso says:

    Thanks For this video Eric 😀.i have a 2009 Chevy Duramax LTZ that would throw 11 to 42 codes after warm up. Let it cool and clear DTC’s would run great until it warmed up. I replaced TCM reflashed it and now all good.

  40. Avataaar/Circle Created with python_avatars John Doe says:

    El Pooh Job Chevy Duramax TCM failure solution? Extend wiring loom so TCM module can be left flapping around outside engine bay in 4 degree slipstream. Then when summer rolls around, poke it through firewall and cable tie it to a HVAC vent and drive with A/C always on high… when that eventually doesn't work anymore, cut the cable ties, that way when it malfunctions it can be slammed against the dash. Works for TV remote, why not TCM.

  41. Avataaar/Circle Created with python_avatars Sonia San Juan says:

    If I replace the module does it have to be programmed?

  42. Avataaar/Circle Created with python_avatars Andy Hagenbuch says:

    rip hammer not claw. rip is strait claw is curved just saying both are hammers. I have been watching your vids for a while and find them extremly helpful in working on my own veh. thank you.

  43. Avataaar/Circle Created with python_avatars Ozzy Krahn says:

    You got codes saying code dump it in the scrap yard

  44. Avataaar/Circle Created with python_avatars Ozzy Krahn says:

    This one is making me laugh

  45. Avataaar/Circle Created with python_avatars david morrill says:

    Glad to see your bald eagles. They are making a great come back

  46. Avataaar/Circle Created with python_avatars FreeRepublicUSA says:

    Man I wished I lived close by. My 06 LBZ/6speed Allison tap manual shift won’t work. I took the column apart and found broken wire where the tilt wheel pinched it. Even though my tow/haul has always worked. Fixed the wires and it still says (6) gear when I shift to (m) manual mode. I even swapped my shift lever out of my other 06 and still didn’t work. I put the shift with broken wires in my other truck and both shifters work as should….Tcm? No codes, no blown ign 0 fuse or any fuses. I’m at my wits end .

  47. Avataaar/Circle Created with python_avatars Matt Man Productions says:

    Why would they put a module that has circuits and since circuits don't like heat and that has heat shields that are to cool off the module, but when it's combating heat from the motor and it's trying to dissipate the heat from itself it grows redundant and no longer works and becomes a heater for the module🤦‍♂️🤦‍♂️ 🤦‍♂️ great job there GM

  48. Avataaar/Circle Created with python_avatars Matt Man Productions says:

    As my grandfather always told me, if it doesn't work get a bigger hammer 😂. He always used to hammer away on things until it work and normally did.. This just shows he was right in his method of fixing haha

  49. Avataaar/Circle Created with python_avatars asymptotic singularity says:

    Don't force it. Use a bigger hammer. Just kidding…… close hood.

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