Hi there,

I have a 1999 GMC 2500 4x4, 6.0L V8. The issue exists with the automatic 4x4 system, or push button 4x4 system.

All of the indicator lights: Auto 4x4, 2HI, Nuetral, 4Hi and 4Low are lit at once. But the truck is NOT in 4x4 mode and pushing the different buttons has no effect.

Each mechanic has told me it will be a major fix and all, but I cant find info or similar issues online to trouble shooot.

Last winter this also happened at like -40'C but it blew the fuse and replacing the fuse corrected the problem. no such luck this time.

PLEASE HELP ANY SUGGESTIONS OR TIPS VERY APPRECIATED!!! Please email to lukeburnett@live.ca many thanks.

 

The simplest thing to try first is to take the 4WD switch apart and see if anything in there needs to be resoldered. If you have a friend with the same truck you can also swap the switches to rule that out. Most of the time when I have found a bad switch nothing lights up on them, but it would be worth a try. There is also a actuator on the transfer case which has a tendency to go out. Try the simple stuff first.

 

It's your push button ... I have a manual transfer case for that very reason... That push button from chevy costs like 600 bucks...open it up and look for corrosion...