shadowofhate

I bought my Blazer a few months ago knowing the 4wd didn't work at all..but hey, it was $600 bucks and runs like brand new. The guy I got it from is a GM Tech, and said that it needs the switch on the dash, the 4wd module, and the vacuum module on the transfer case I think. Well before I buy all that stuff I want to narrow it down first.

The switch doesn't light up at all, in fact I don't think there's power running to it all...I don't hear any relays or anything clicking at all. Any clue?

shadowofhate

Ok there's power running to the switch, but it doesn't light up at all...even in 2wd. The bulbs are good also.

Where is the t-case controle module?

MT-2500

First thing check for codes on it.
Jumper pin 13 on diagnostic to ground and read codes and post back code no.

__________________
Remember proper testing gives us the answer to many problems.
MT

shadowofhate

I thought you could only flash the codes with OBDI, mine has OBDII and the ECM is on the pass. fender.

MT-2500

That is on engine codes.
The pin i3 is for transfer case codes.
Give it a try.
And let us know what you find.
MT

__________________
Remember proper testing gives us the answer to many problems.
MT

detectingcoins

I have a 94 Jimmy with same problem. I tried everything,,,,new vacuume switch (on top of Transfer Case, with 3 woses). TCCM, Vacuum mod under battery.
The only time the lights on the switch would light is when I first turned the keys on.
I jumped the test panel under the dash and got a #2 code which flashes on the 4x4 switch itself, meaning it was the encoder motor. I DO have instructions on how to check the harness for problems.
I also learned that the ground wire runs through the neutral safety switch on the steering collum. I went under there and wiggled some wires and low and behold,,,,I have 4x4 now.
Good luck,
let me know if you want me to send you the instructions to checking the encoder motor.