hey everyone, my vehicle is as follows:

2005 jimmy 4auto 4l60e

Here are the symtoms
- no 4x4
- none of the indicator lights show on the button (backlight still work)
- even when I turn the key, nothing on the buttons except the backlight
- I switch from 4 auto to 4hi last week and everything just quit
- service 4wd light came on

Here is what I troubleshooted
1) remove TCCM, observe, clean pins, put back in - no help
2) after the above, now my service 4wd light doesn't come on (even when I turn the key......
3) removed encoder motor plug, observed, no corrosion
4) checked for vacuum to the front solenoid (on firewall, 4auto version) and the vacuum was good
5) tapped the encoder motor with a rubber mallet, nothin
6) tried the 'positive and negative' terminal trick, nothing
7) finally, I removed the 4x4 switch/buttons, unplugged, looked, nothing out of the ordinary


So, that's it. If I had to guess, I would say TCCM since I have no more service 4wd light (I guess I have to check the bulb) and none of my lights turn on my 4x4 switch (except the backlight),

Any help or tips troubleshooting further is appreciated. Thx guys

 

Have you been hearing any light clicking sounds from your TCCM recently or in the past? They will do that before they fail completely. To me, when it was failing, it sounded like it couldn't decide what state to put itself.

 

Check ATC fuse in under the hood relay center and 4WD fuse in fuseblock at left side of dash - report back with findings.

 

Oh.......... My............. God.................

ATC fuse was blown. As soon a I put a new one in I heard that transfer case motor clicking around. Thank you for this.

What is the difference between the 4x4 fuse inside, and the ATC fuse inside the hood? I'm guessing ATC is for the transfer cause (AutoTrac)?

 

Disconnect and inspect TCCM connector terminals for corrosion, especially big red and black wires. Remove encoder motor and make sure you can click through transfer case range with a wrench on the shaft. DO NOT hook up encoder motor without being actually mounted on the transfer case. Report please. Pics if corroded terminals please.

 

I'm sure you're going to need an encoder motor as little else can draw enough current to blow a 20A fuse. Question is if transfer case is preventing it from turning, or if poor connection caused it to fail (other problems as well).

There are several fuses involved in the 4WD system. ATC is the big kahuna for the encoder motor. The others are just for the controls.

You can look at this thread for information and wiring diagrams. https://blazerforum.com/forum/2nd-ge...-blazer-89044/