Hello!

I have a 2001 GMC Sonoma 4x4 with an uncommanded 4x4 problem.

Driving to work yesterday and this morning, when I arrive I'm finding the truck in 4 Hi. I have no recollection of pushing the 4 Hi button. Tonight on the drive home, I watched the 4 Hi light come on solid and the 4 Lo start flashing. No button presses from me. I pushed 2 Hi, and less than 30 seconds later the same thing happened and I recorded the clip below.

The truck is definitely engaging 4x4 and pushing 2hi is definitely disengaging. I've been searching and reading but haven't come up with someone having the same problem where it engages itself.

Any thoughts?



Gif of problem

 

Maybe it's something in the 4wd switch? Like the contacts are making up or something?

Might be worth a try to unplug the switch and see what happens

 

...... I'm ashamed to say that didn't cross my mind. I'll try that and see what happens!

 

If you have the 3 button 4x4 system, those switches are known to have a cold solder issue. I never had my 4x4 engage on it's own, but mine did have issues with engaging properly when the button was pushed. Taking the switch apart and reflowing all the solder joints on the board fixed the issue for me on my 2002 Sonoma.

 

Update.... I removed the switch and the problem went away. So, then I took the switch apart and there was a burn spot where the 4 LO button is on the circuit board. Replaced it with a NOS part from eBay and haven't had the problem since.

 

Thanks for checking back in and closing the loop on your question. I'm glad you've solved the issue.