Chevy Duramax w/ Allison Trans: TCM Failure
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Date: 2020-08-05
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Comments and reviews: 10
Robert
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. ;)
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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. ;)
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Felipe
Yep, I just had this same issue happen to me (yesterday) in my 2014 GMC Denali 2500HD - Duramax w/ Allison. After researching for a few hours all signs pointed to Dans Diesel Performance TCM as the cheapest and fastest fix. I had a hard time pulling the trigger on a 675 part with 93 overnight shipping so I called them up and spoke with Dan. I ran through my issues and what I had done to test and he was extremely helpful and reassuring. I had the part next day (today) by 11AM and had it installed by 11: 05AM.
It royally sucks to have the problem but this is definitely the best approach and in the long run likely saved me 300-500. Not to mention if I had taken to a shop i would have been without my pickup for at least 3-5 days.
Install is super easy by the way. no tools required for my pickup.
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Yep, I just had this same issue happen to me (yesterday) in my 2014 GMC Denali 2500HD - Duramax w/ Allison. After researching for a few hours all signs pointed to Dans Diesel Performance TCM as the cheapest and fastest fix. I had a hard time pulling the trigger on a 675 part with 93 overnight shipping so I called them up and spoke with Dan. I ran through my issues and what I had done to test and he was extremely helpful and reassuring. I had the part next day (today) by 11AM and had it installed by 11: 05AM.
It royally sucks to have the problem but this is definitely the best approach and in the long run likely saved me 300-500. Not to mention if I had taken to a shop i would have been without my pickup for at least 3-5 days.
Install is super easy by the way. no tools required for my pickup.
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FreeRepublicUSA
Man I wished I lived close by. My 06 LBZ/6speed Allison tap manual shift wont 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 didnt 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. Im at my wits end.
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Man I wished I lived close by. My 06 LBZ/6speed Allison tap manual shift wont 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 didnt 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. Im at my wits end.
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charlie
I have a 2011 2500 Duramax I was sitting with that Idling for probably 20 minutes and Service stable track and the service engine light came on went to put it in gear and it would not go shut the key off turn the key back on truck would go into gear but would not display on the gear selector and was stuck in second gear with only go into reverse and second limped it home and shut it off for a little bit started it back up light was out Im thinking I have the same problem TCM what do you think
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I have a 2011 2500 Duramax I was sitting with that Idling for probably 20 minutes and Service stable track and the service engine light came on went to put it in gear and it would not go shut the key off turn the key back on truck would go into gear but would not display on the gear selector and was stuck in second gear with only go into reverse and second limped it home and shut it off for a little bit started it back up light was out Im thinking I have the same problem TCM what do you think
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Dillon
I did a voltage test and could only get 10 and 70 to light up. Even when the key is turned on 9, 63, and 69 did not light up. I believe I have a bad TCM due to throwing the same P0708 code. I am going to have the range shift checked on a quality scanner along with any more codes that show that a lower end scanner cannot do. Truck went into limp at startup in a parking lot with the same lights and service messages as this truck in the video did.
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I did a voltage test and could only get 10 and 70 to light up. Even when the key is turned on 9, 63, and 69 did not light up. I believe I have a bad TCM due to throwing the same P0708 code. I am going to have the range shift checked on a quality scanner along with any more codes that show that a lower end scanner cannot do. Truck went into limp at startup in a parking lot with the same lights and service messages as this truck in the video did.
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John
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.
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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.
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Roland
South Main Auto Repair LLC. I have a 2012 2500HD GMC. I purchased it used for Dealer. it has been De-tuned no DEF etc. and has a chip. My issue is when diving normal take it easy she drives great. BUT when I punch it she down shifts but won't shift to the next gear unless I let up and then punch it again. It doesn't do it all the time but it does it. What is it? is it the TCM or the TRANS. PLEASE HELP///
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South Main Auto Repair LLC. I have a 2012 2500HD GMC. I purchased it used for Dealer. it has been De-tuned no DEF etc. and has a chip. My issue is when diving normal take it easy she drives great. BUT when I punch it she down shifts but won't shift to the next gear unless I let up and then punch it again. It doesn't do it all the time but it does it. What is it? is it the TCM or the TRANS. PLEASE HELP///
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Gmtail
It would be really cool if you could colab with other YouTube guys that do component level repairs like jeffescortlx. Granted, once the module is broke it's done and a new one is out the door but the knowledge coming from seeing what actually went wrong would be invaluable.
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It would be really cool if you could colab with other YouTube guys that do component level repairs like jeffescortlx. Granted, once the module is broke it's done and a new one is out the door but the knowledge coming from seeing what actually went wrong would be invaluable.
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Alex
These trucks are notorious for the plugs to the tcm vibrating loose and causing intermediate codes. Gotta unplug them and reseat the pins to ensure a solid connection. I see that 9/10 times with people complaining about hard shifts and other weird issues.
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These trucks are notorious for the plugs to the tcm vibrating loose and causing intermediate codes. Gotta unplug them and reseat the pins to ensure a solid connection. I see that 9/10 times with people complaining about hard shifts and other weird issues.
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Sam
If that module is mounted to the rad. shroud, Id remove it then drill one big hole with a hole saw or a mess of small holes in the shroud then remount the mod. over the hole(s. Maybe that would improve air flow to help cool the mod.
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If that module is mounted to the rad. shroud, Id remove it then drill one big hole with a hole saw or a mess of small holes in the shroud then remount the mod. over the hole(s. Maybe that would improve air flow to help cool the mod.
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