So I have a 2004 blazer Zr2 with the 4 button 4wd
i have searched a lot of threads but I need some direction. When I first got it there was no lights on the 4 buttons. Nothing happens when you hit them. I know there’s a vacuum actuator at the front that goes to the diff, the diaphragm looks good and works. I have put my blazer on four jack stands and tried to bypass the vacuum solenoid by connecting the vacuum line before and after so the actuator is pulling the diaphragm. When I put t in gear, all 4 spin, and I put it on the ground out of the garage, onto ice, only the rear tires spin. I then replaced the dash switch, encoder motor and tccm. Now the lights turn on but it says it’s in 4hi, but the Tcase is still in neutral from installing the motor. I don’t know what to do. Don’t want to spend a fortune at the dealer. Please help

 

Did you use new parts or junkyard parts? Give me the part numbers you installed. Did you inspect the TCCM connector terminals? Do the lights flash when you push a new button? You did connect the second connector for the encoder motor, correct?

 

I have used remanded parts. Dorman 599-102 tccm and dorman 600-901 encoder motor

 

And what about my other questions please.

 

Terminals looked fine, I used contact cleaner and dielectric grease on it. The lights do flash but just continues to flash, then I turn it off and try again and the lights are off. I just put the connections on, is there a special way to put it on? And are you referring to the connector and wire on the encoder motor itself or the connection on the back of it?

 

I was talking about both of the wiring connections to the encoder motor - just trying to ensure you had them both plugged in.

Parts you listed are correct.

This continuous flashing lights on one key cycle and then no lights on the next key cycle seems pretty strange behavior. How are you able to get them to flash again, once you have turned it off and the lights are off on a cycle? I suppose you could have a defective TCCM, but in reality that's probably not the case. Unfortunately, there is only so much you can do for diagnosis on 4WD without a Tech2 and it seems you have it covered already other than checking the wiring terminals on the connectors that plug into the encoder motor and the oddball array of fuses that gives input to the 4WD system. Illum and 4WD in IP fuseblock, 4WD and ATC in Underhood relay center.

Did you say that your TC is physically in neutral and vehicle will not move?

Some info on your system here: https://blazerforum.com/forum/2nd-ge...-blazer-89044/

 

So I found that the ATC fuse blew out when I was trying yesterday. I have replaced the fuse and still no lights on a new key cycle. But now i believe it is in low range(just rears) with no 4wd dash lights. I’m so confused.

 

I would concentrate on finding out why the ATC fuse blew and you will will probably find the rest of the problem. Wiring schematics are in the link that I gave.

 

Everything is all functional now. Brought to the dealer and for $230 they installed the encoder motor and programmed the tccm. Just some tccm codes was the problem they said

 

Glad to hear you have success!