I have a 2000 silverado 1500 and when I put a scanner on it doesn't connect to the tccm. I just bought the truck and the 2high and 4lo buttons were lit up so I bought an encoder shift motor and now all lights are lit up on the switch. Then I plugged a scanner in it and it says no communication with the tccm and the hvac modules. Any help would be greatly appreciated.

 

You likely need a professional level code reader/live data scanner in order to connect to and read the TCCM, HVAC module, ABS module, etc. Most consumer level/DIYer OBD II code readers/scanners only connect to the ECM/PCM.

 

Check your fuses for the TCCM. There is a 4WD fuse in the instrument panel fuse box and an ATC fuse in the underhood fuse box.

 

Yes sir I have an autel maxisys ms909 and it wouldn't communicate with the tccm or the hvac. I have checked for power and ground to both and checked and cleaned all fuses. Cleaned and retightened the grounds. New encoder motor and switch. Just wondering if I missed anything before I buy a module
thank you all for any help

 

Turns out it was an intermittent loose orange power wire into a connector in the back of the i/p fuse block. Always check your powers and grounds repeatedly and give them a tug.