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2011 GMC Sierra 2500HD Denali 110K

So I think my TCM decided to take a dump. Getting P0700 and P0708. Got it to limp home and shut it down for dinner. 1/2 hour later it goes into a high idle at start up (800 rpm, regen not possible) won’t go into any gear, shift indicator message, getting a surge in at idle. Checked the wiring seemed fine. Pulled the TCM off tossed it in the freezer and the thing works great 10 min later. Does anyone have an Allison 1000 A50 T14 TCM that works that they want to sell?
 

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Welcome to Duramax Forum!

Unfortunately LML TCM's are the new FICM's. Dropped my LBZ off at the mechanic yesterday to get 8 new Bosch injectors and he told me that he has 3 LML's that need new TCM's. Every "Emergency" request for a LML TCM is canceled by GM and all other OEM part houses.
There are no new TCM's available so I would start calling around for a used one from reclamation yards...

You may try contacting Alligator Performance in Hayden ID... www.alligatorperformance.com
 

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Spent most of the night searching. The price of these has gone up 6x the original in the last month. Some asking ask much as 9k on eBay and my local wrecking yard now wants 2k a pop after you’ve waited your turn. I’m going to send mine off for repair and pray it isn’t fried. I’ve also added my name to the long back order list. But I’m still open to offers if anyone wants to sell theirs!
 

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From the description of the problem -doesn't work when hot but works when cold - that sounds a lot like a bad solder joint to me. I think this might be a good candidate to send to a repair facility. Before sending it anywhere, call them and ask questions. The cheapest is not necessarily the best repair facility.

I saw a post in the last day or so about a TCM for a 2011 and the new price on Amazon was something in the neighborhood of $350. What is the part number and service number for the TCM for your truck?
 

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From the description of the problem -doesn't work when hot but works when cold - that sounds a lot like a bad solder joint to me. I think this might be a good candidate to send to a repair facility. Before sending it anywhere, call them and ask questions. The cheapest is not necessarily the best repair facility.

I saw a post in the last day or so about a TCM for a 2011 and the new price on Amazon was something in the neighborhood of $350. What is the part number and service number for the TCM for your truck?
I believe that’s probably what’s going on with it. It’s the original TCM so I’m not shocked. Most repair facilities I’ve spoke to won’t touch it right now with the shortage going on. The only place I found willing to repair it was G7computers. Thankfully I was able to find a used one with a 2017 manufactured date as well as another spare from a wrecked truck. I’ll report back with how it works out sending it for repairs. Doorman has a projected stock date of November but who really knows. These are being held for ransom right now because Gm has no ETA for their back orders.
 

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I believe that’s probably what’s going on with it. It’s the original TCM so I’m not shocked. Most repair facilities I’ve spoke to won’t touch it right now with the shortage going on. The only place I found willing to repair it was G7computers. Thankfully I was able to find a used one with a 2017 manufactured date as well as another spare from a wrecked truck. I’ll report back with how it works out sending it for repairs. Doorman has a projected stock date of November but who really knows. These are being held for ransom right now because Gm has no ETA for their back orders.
Part # is 24256861
 

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My 2012 TCM and PCM are being looked at now at autocomputerspecialist.com in Florida. I have had a conversation and emails with them. Hopefully, I will get it back before Thanksgiving, install them and update here.

I feel GM has failed us all badly. Even the dealership where I took it did not help or treat me well. I won't go into all that bs here. If anyone else has updated experiences with their repair from autocomputerspecialist.com, let me know how your modules and auto is doing please.
 

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Any luck with your getting TCM repaired? I have a 2011 GMC with a bad TCM and can’t find a replacement anywhere! Mine has been out for a couple months and they seem to be on back order everywhere.

thanks
I sent mine to Auto Computer specialist in Florida. They did some work on it and send it back to me. It appeared to be working for the first two short trips that I made. The second trip was approximately 50 miles in 1 hour long. The next day it was doing what it was doing before it was repaired. So I contacted ACS and I am sending it back to them today. I have had phone calls with a couple other people on this form and we all seem to be having the same problems or indications with the transmission. I'll let you know more if you like we can have a conversation. I've talked to one other guy on the phone and he should be receiving his back from ACS soon. Another guy I spoke with, is waiting to hear how mine turns out.
 

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2011 GMC Sierra 2500HD Denali 110K

So I think my TCM decided to take a dump. Getting P0700 and P0708. Got it to limp home and shut it down for dinner. 1/2 hour later it goes into a high idle at start up (800 rpm, regen not possible) won’t go into any gear, shift indicator message, getting a surge in at idle. Checked the wiring seemed fine. Pulled the TCM off tossed it in the freezer and the thing works great 10 min later. Does anyone have an Allison 1000 A50 T14 TCM that works that they want to sell?
We all sincerely feel your pain brother!
Used on the bay 3 to 4k.. new on the bay 5 to 9k
Keep a positive frame of mind... especially when a new one from GM is $750.00. But none are being produced right now.
 

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Bump Bump, any luck? I'm pretty sure mine is bad as well. First the inhibited shift, disconnected the batteries and presto changeo, it worked. I soon realized that if I started the truck before all the dash lights and dinging stopped, it would inhibit shifting. All of a sudden, started getting a delay in 3-4. Then, hard shifting and slipping/delay all the way up and hard shifts all the way down. When almost stopped, the rear tires would skid, trans locking up. I can't go forward until shifting into reverse, waiting for it to shift, then drive when it takes a bit to get going. I disconnected the batteries for 8 hours today and tried again. It only got to 50F today, but no luck. The 2 mile drive home was just as hectic.
 

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Bump Bump, any luck? I'm pretty sure mine is bad as well. First the inhibited shift, disconnected the batteries and presto changeo, it worked. I soon realized that if I started the truck before all the dash lights and dinging stopped, it would inhibit shifting. All of a sudden, started getting a delay in 3-4. Then, hard shifting and slipping/delay all the way up and hard shifts all the way down. When almost stopped, the rear tires would skid, trans locking up. I can't go forward until shifting into reverse, waiting for it to shift, then drive when it takes a bit to get going. I disconnected the batteries for 8 hours today and tried again. It only got to 50F today, but no luck. The 2 mile drive home was just as hectic.
Sorry to say your transmission seems to be acting up much more than mine. However, neither one is a good scenario. So I'm waiting for my TCM to come back from ACS in Florida for the second time.
 
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