2500HD Code U0101 Service Stabiltak light / Transmission in limp mode

Cmcrice89

New member
Jul 4, 2020
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Help please!
I have a 2009 2500HD with code U0101 and the services stabiltrax and engine light on with transmission in limp mode. I found leaking internal transmission wiring harness leaking. Replaced it and still have same. Spiral batteries were 9 years old, even though they showed to be still good I went ahead and replaced them. (Figured I can use those batteries in the boat.) Still the same. Tested ground cables from each battery to block ( tested to 0 ohms) cleaned each block location at ground contact, still the same problem. Added additional ground from cab to block, still same problem. I don't have a schematic of the TCM but tested plug at TCM found 2 good constant batteries, and found 2- good ignition batteries. Have not tested to plug at internal harness, does anyone know what pin configuration I should look for at the transmission and can anyone tell me if I need to see more batteries at the TCM? Also how many grounds should i see at the TCM and where in the pin location would they be? Kinda getting to a loss here, any help would be greatly appreciated!!
 

Ron Nielson

Active member
Oct 11, 2009
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Berryton, KS
Go to GMUPFITTER.COM, look in the body builder section, then look for your year/model, then look for the electrical manual for your year/model. Not every part of every circuit is there, but most are.
 

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Cmcrice89

New member
Jul 4, 2020
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Thanks Ron, all really great information, unfortunately no details for the TCM, or at least not that i could find.