Hence the motor running - pause - and then running again. I get it. Keeps looking like transfer case is screwed and motor can't quite move all the way to the position it wants, but I'll spend the $113 to make absolutely sure its not shorted TCCM before giving up completely. If/when I give up on this vehicle (which seems to be of female gender) I'm sure it will feel a lot like a very nasty divorce after a super hot attraction and whirlwind courtship - followed by a short and very disappointing marriage - all in spite of tons of work and effort to save it!!!! At some point one simply needs to cut your losses. One more chance..... But I've said that before (I really love this vehicle - it's so pretty and fine and lovely when it is behaving!) We will have to see. What else would I do with my time?

Thanks Captain,

Les

 

Guess what - the new TCCM fixed the remaining 4WD issues. All of the 4WD functions work fine now - even goes into 4LO and back out! So seems that when the encoder motor shorted and died (which it definitely did - even blew fuses for a while and then fell completely silent), it also managed to damage the TCCM which could not correctly recognize the position of the transfer case, even with the encoder motor sensors operating properly in the new encoder motor. Like I said, the two encoder signals that were both pulled to ground were beside each other on the board in the TCCM. Seems these two circuits were shorted together inside the TCCM and causing the position problems. Guess GM wouldn't have allowed this TCCM replacement under warranty as there was communication with the TCCM and no code - yet the TCCM was bad (service bulletin). Goes to show you there is always an exception. I am really happy about finding the OBD2 Terminal commands to communicate with the TCCM. Seems this is a quite valid way to read and clear TCCM codes.

Les

 

Cool! Glad you've got 4WD now! Just in time for Summer 4WD fun! Thanks for posting back.

 

So I purchased an encoder motor from a junkyard. Unhooked the old encoder motor off of my transfer case and hooked up the power plug from the new encoder motor without mounting it to the transfer case. Hopped in the truck turned key over and the switch inside the truck indicated that it was I'm 4 wheel Drive high. So I push the switch 2 to two wheel drive and now there's nothing.... Can somebody help me please.

 

Read the first line in bold under TCCM installation here: http://my.cardone.com/techdocs/930870-83.pdf The encoder motor has a position sensor that does not locate on the motor - it locates on the shaft coming out of the transfer case. Encoder motor also has a brake that requires current to release the brake before it will even move. Have no idea if you burnt it up or blew a fuse or just needed to ground the encoder motor???? You will have to install it to diagnose. But difficult to do if you don't really know if the rest of the system is good. So why are you replacing it in the first place?

 

^^ X2 Probably destroyed the encoder motor by operating it without it being installed.
There is an alignment tool that must be used before installing the encoder.

 

Hi Captain!!

 

New to forum and sorry to dig up old thread. I just got a 2001blazer 4x4 that was sitting idle for who knows how long. I was told 6 months but I wouldnt know if that was true or not and I can't figure out why 4wd doesn't work...no indicator lights on 4 button switch..i have illumination though. Can't hear any clicking anywhere. TCCM? located on passenger side kick panel correct? Took plugs off and looked corroded. Sprayed them with electronic cleaner then put dielectric grease on them. I've read quite a few posts on this site but some answers are for the 3 button switch which I'm assuming is different than the 4 button switch which I have. Ive checked the ATC fuse and the 4wd fuse and they both are good. Any help in figuring out what is wrong would be greatly appreciated.

 

This is a necro post! Please start your own thread and I will attempt to help you. Thread closed.