GMC Sierra 4 wheel drive won't disengage

I have a 2003 GMC it has two buttons to use 4 wheel drive as most all do with push button controls...One is for standard highway driving with 4 wheel drive the other is for 4 wheel drive a low speeds for off road driving and conditions that need low speed less spin driving..not designed for highway use..and must be stopped to engage where 4 speed highway can be shifted on the go..hope this answers your question..good luck..

hi
yes seems like you switch is faulty.]
replace the switch
Thanks

try selecting from nutreul or less then 3km

Drive forward, put it in neutral, the into reverse. If you have not used the 4wd for awhile it will need vacuum to activate and disengage

My 00 did the same thing , If you did get it in 4x4 it took 30 minutes pushing 2wd to get it back..I change the selctor switch work'd fine since. About 40 50 bucks.HOPE THIS HELPS

I believe the 4 wheel drive is engaged by a vacuum actuator on this model. Look under the hood for a rubber "banjo-like" diaphragm that has a cable coming out of the middle of it. If I'm right, you'll find a tear in that rubber diaphragm. Post back if this doesn't work and I'll dig deeper. Check that first though.

The engagement piston might be dirty causing it not to fully engage. Also check your linkage on your transfer case.

I am not sure about Ford, but several of the 4x4 models use a vacuum hose connected to engine vaccum to switch the 4x4 functions. If you have a push button engage system then you may want to check the rubber hoses around the front drive shaft. This only applies for the push button models.

sometimes it helps to back the truck up a little ways, for some reason it helps lock it in.

if the light just flashes then you blew a fuse check all the fuses in the cab and in the engine bay, if none blown, then you have a broken wire