Hi everyone, my first post here. I have a 4 button NV236 transfer case Blazer, the truck is clean, and low mileage.
The Service 4WD light stays on and all lights on the switch buttons flash and then stay on.
I checked all fuses, and connections I could reach, and found everything in good condition. I tried all resets, and replaced the switch module. I the Blazer checked with a tech II and found the scanner was unable to communicate with the TCCM, no codes available, everything else seemed OK, This indicated a bad TCCM.
I picked up a used TCCM and installed it, leaving the battery disconnected for more than 1/2 hr. When I powered it up, The Service 4WD came on again, but now the switch button lights flash quickly once, and then all go out, and stay out.
I put the original TCCM back in and all switch lights again blink and stay lit.
Any Ideas? Does anyone know of a place that can test, and maybe repair a TCCM? I would like to know the status of the TCCM before more trouble shooting.
Thanks in advance for any replies.

 

im having the same issue...the words "service 4x4" is not what i wanted to see on this years first real snowfall after a 12hr shift...
please keep me updated with your progress, im going to be speaking with a gm shopforeman tomorrow and see what he can tell me. my service 4x4 light flashed 5 yrs ago and it wouldnt go into 4x4 but the next day it worked and i never had a issue untill today, and i use to use 4x4 a lot.