NEED HELP C0321/4x4 issues on silverado

To begin, yes i have read thru many posts close to mine but no luck yet. I will start at beginning and run thru all i have so far. I have an 05 silverado and original issue was when making hard turns in driveway and parking lots, the truck felt like 4wd was locked in, although switch indicated its in 2hi. Well 3 days later 4wd switch didn't have any lights on and "service 4wd" popped up on cluster. Well i started at switch and tested the ohms and all was good except Auto4wd, got new switch and same deal. Tested it and it ohm'd exactly the same as old one. So before i spend more $$ random replacing, i paid a guy i know with a tech 2 scanner and he gave DTC: C0321. Just cant remember which one exactly and he done cleared his scanner. But along the lines of circuit malfunction. He said his best idea was a wire issue. So i start by cleaning grounds at drivers cab bushing. No change. So i test the 12v (orange), ground (black) and "low volt signal wire" (red) at the connector for encoder motor. 12v and ground was fine but the "red" was not giving any power. So i followed red wire thru harness, testing in several spot, as i have heard of pinching issues, and ended at the tcc module. At the module black 4 pin connector, again i tested 12v and ground, fine. But still nothing from the red. I went and got a used module from truck with blown engine. Put it in and still having same problem. Once again i test red wire but this "new used" module is giving 1.3v thru it from module all the way down to encoder motor connector. Have read its suppose to be 5v thru that wire. Put my old one back in and its testing 1.3v exactly also. Im at a stand still and not sure what to try next that doesn't cost me a encoder motor without certainty. Also i must add, while hooked to tech2 scanner, he was able to manually switch it between 4hi,4lo and 2hi so i really don't believe the issue is in the actuator on the differential, since it was locking into gears and operating actuator. I have removed 4wd driveshaft to try and test encoder wires closer to housing.
 
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Let me correct myself as i somehow got screwed up on wiring diagram. The red wiring i was originally testing is actually the shift motor b. I have went back and tested the green/black and do have the 5v there going to encoder motor. Curious about testing the encoder motor. I have read NOT to bench test as it will break internally but read about testing th ohms between 2 wires going to the encoder, just not sure which two to use.
 

Mooseman

Moderator
Roadie has been inactive for a few years now and unfortunately, I don't have any real experience with the Silvy's 4x4 system. If it's anything like the TB's, you could try using this thread from the GMT360's:
4WD not working? Step inside.
 
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I appreciate it. I wasn't even sure if i could tag but seen i can. Also after i tagged roadie, seen he hasn't been active for a while. Im gonna see if the local junk yard would happen to let me trade the module i bought for the encoder motor, if not i found one local for $50. I've traced all wiring and all checks out, and I've replaced all other parts so im gonna try the encoder that most have had issues with. I really appreciate it man
 

Mooseman

Moderator
I also changed your title a bit for hopefully more repsonses. We do have a few members with full size trucks that hopefully can chime in.
 
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I appreciate it so much. I decide to to ahead and pull encoder motor to check my connections inside. I open it up and it is full of moisture and looks like it has a while. Connections have green on them but the actual motor housing is broken. Im gonna swap it out when i pick the other one up and hopefully it will be fixed. Will post back with confirmation

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