2000 GMC Jimmy 4x4 2-DR 4.3

Okay so where to begin I’ll try to make this short and sweet. The other day while driving home from work from a dead stop my 4x4 was trying to engage partially it almost sounded like I had cards on my rims almost like a dirt bike then when I hit the brakes to slow down you could hear a loud clunk from the passenger front then it would stop.. It wouldn’t do it all the time just randomly. I’ve done my fair share of research (I believe) so I checked my Vacuum line actuator and noticed there is no play in the line and the diaphragm is completely pressed in and everything is tight. I think that would mean it’s in 4x4 even though my buttons says 2HI… next on my list is to check / replace the Vacuum Actuator Switch on top of the transfer case hoping that will be my problem. Currently the fuse is blown for the 4x4 not sure if that another symptom or not but it hasn’t been doing it the past 2 days. I am currently waiting for the actuator switch to be delivered (if im going to take the old one out I might as well replace it). I am just looking for people who’ve had the same experience and maybe some things I should expect and advice.

The video shows no movement in the actuator while truck is running switching between 2hi and 4hi i can hear it trying to switch but nothing happens. (i put a fuse in just for the video)

 

Well it was the Actuator switch on top if the transfer case that was my problem. The line moves freely now without any problem.. But now every time i push the brake down the fuse blows. Ive already check the the TCCM for corrosion and cleaned it up.. still not working also found a ground close to the actuator under the battery tray cleaned that up too.. No luck. Does anyone know whats going on? im not the best at electrical work but i can try my best. Ive read a lot of the other post but am a little lost.

 

2000 GMC Jimmy 4.3 - 3 button 2hi 4hi 4lo

I know there are a million threads for the 4x4 problems but i can not find one for blown fuses. I just replaced the actuator switch on top of the transfer case and everything was working fine 4hi and 4lo are engaging with no problems.. Then i take it for a drive get up to 80km/h and the fuse blows.. now i cant even roll out of the garage without the fuse blowing. soon as i hit the brake you can hear it pop and i lose the lights to the switch. I just cleaned up the TCCM there was hardly any corrosion anyways. I also found a ground for the Actuator under the battery tray cleaned all that up and no luck. ANY advice would be appreciated or if there is a thread with the same symptoms as mine please re direct me. Thanks

 

Try the "Search" button

https://blazerforum.com/forum/tech-a...ill-help-7180/

 

Okay after hours of research and bunch trial and error. How do i ground PIN #13 ? do i just run a wire to it and ground it? im trying to find some error codes with my TCCM.. any help would be appreciated

EDIT- Figured it out. Just having trouble identifying the code could anyone one help? Hopefully i am not talking to my self starting to feel that way.

 

I have read almost every post and have tried everything. I cannot find anything similar to my problem. my 4x4 engages fine except 4lo. then when I drive away the fuse blows.. if you can prove me wrong and find a thread simular to mine I would love that.

 

There are several fuses involved with 4WD, both in the instrument panel fuse panel, and in the underhood fuse panel. Which fuse is blowing when you hit the brake?

 

It's the 4wd fuse in the instrument panel number #15 blows everytime I've looked at all the others under the hood there fine. The fuse original blew when the actuator switch went and the hubs were trying to engage. So I'm thinking it's maybe the TCCM?

 

https://blazerforum.com/forum/2nd-ge...-blazer-89670/

Circuit 241 from fuse 15 goes to your control switch, Your TCCM, and to your front axle indicator switch. It continues on to your PCM as circuit 1695 and also feeds into your ABS. Will need to isolate cause of high current draw. See link above for wiring schematics.

Sounds to me like your ABS is popping the fuse if it blows when you hit the brakes.

 

Yup, it's a brown wire and feeds several things for 4WD: VCM, 4WD dash switch, and the front axle engagement switch on the right front axle tube next to the front differential. Will need to disconnect each one separately and see if the fuse stops blowing, then trace it down. No easy fix here, it's a matter of tracking it down. I don't see anything in the schematic that has a direct relationship with the stop lamp switch. Not saying it's not possible, but don't see any direct connection. First place I'd check is the axle engagement switch & harness.