Hi, I am new to this, really hoping someone can help me out. I have a 2000 blazer LT 4x4 with 4x4 auto. It will not shift out of 4hi. I took the battery and battery pan out to determine that it is actually in 2hi when it is in park, and it engages into 4hi when the ignition is turned on. I then did some research and found out that the TCCMs on these things go bad all the time. So I took mine out and it stayed in 2hi after ignition. Awesome. I proceeded to order a used one on ebay(because I'm cheap) only to receive it to have a completely different problem. It shifted through the gears but not corresponding to the button that you pushed. I assumed it was another bad module, the seller guaranteed it was good, but send me another one after I returned it. I received that one today and it does absolutely nothing. I'm at a complete loss. There is minor corrosion on the harness but nothing extreme. Does anyone have any advice? Any feedback will be highly appreciated.

 

Don't know if this will help but I found with my 1999 trailblazer that the wiring going into the module was bad....Left it doing all sorts of wierd things. hope this helps.

 

For anyone who cares, i kept trying TCCM's until i got a good one and it solved the problem. They go bad often and many bad ones get sold. Make sure you buy from someone reputable.