Chevy Silverado and GMC Sierra Forum banner

4X4 Problem

2K views 11 replies 7 participants last post by  masterem88 
#1 ·
Good evening,
I'm trying to fix my dad's 2003 GMC Z71. It has the automatic 4x4 option. It seems to go into four wheel drive like normal but when you try to switch back to 2 wheel high you have to hit the button 5+ times before you hear the "clunk" and it switches back. I have read that the 4x4 selector switch's on these models were not that great. Does anyone else have a similar experience? Would you agree that this would be the first thing to try? If so is it very difficult to get the switch out? I drive an 84 GMC.. much simpler! Thanks!
Michael
 
#4 ·
You may also want to do some research on encoder motor/sensor concerns. We have replaced quit a few at the shop and my truck needs one. does the service 4wd lt ever come on? If it does you could get it scanned to see what code is present which may help the diadnosis.
 
#12 ·
the enocoder motors on these trucks are (excuse me for saying such a thing here) junk! if you are pushing the selection you want on the switch, no matter which one it is, and that selected light flashes at all, then you know the switch is working because it only starts flashing like 4 or 5 times as its trying to engage because it recognizes your selection. but the weak link is that these encoder motors get weak over time (just like starter motors do) and dont have enough strength to move the shaft and shift fork. i have seen quite a few corrode between the encoder motor and t-case even though there is a gasket between it and the corrosion works its way to the inside of the motor and foams out. obviously if you have a good enough scanner to scan the t-case module then do that and see if there are stored encoder motor circuit codes. i would then remove encoder motor from t-case (which requires removal of front driveshaft) and manually rotate the shift arm coming out of the t-case and see if you can with decent effort get t-case to shift into 4 positions, you'll feel them clunk into position. If not then i would suspect internal t-case shift fork wear, if so then i would replace encoder motor. i think through our shop from the stealer dealer is like 125. so normally around 180. but DO NOT BUY AFTERMARKET! and DO NOT TRY TO SHIFT THE T-CASE WITH SWITCHES WHEN ENCODER MOTOR IS REMOVED. I have heard of way to many people trying this to see if motor actually moves and its instant encoder damage. hope this helps.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top