GM 4WD problem

Dr. Teeth

Dr. Teeth

Club Member
From time to time my 2003 GMC Sierra will give me a message that the 4WD system needs service and the buttons will be non-functional. Seems to happen when it gets really cold and is intermittent. I hear either the keypad is bad or the servo motor but I'm not a parts changer kinda guy, wondering if any MM mechanics have seen this or know what usually goes bad and how to test.

Thanks,

-Teeth.
 
My dads S10 does the same thing. He unhooked the battery and resets the computer and it fixes it for about 4 months. Never had the time or patience to look into what causes it though, and trucks not worth sending in to get fixed.
 
my astro van does this (I know its AWD) but my reading found that it might be a sensor that needs to be cleaned off...One of the speed sensors gets dirty and throws the light. I have always just keep driving it and it will cycle back to off :) I know, lazy fixes are crappy.
 
There should be some error codes stored in the Chassis module. Get it hooked up to a Tech II to pinpoint it.
 
beertestr said:
There should be some error codes stored in the Chassis module. Get it hooked up to a Tech II to pinpoint it.
Click to expand...

We have one of those at the shop. I'll get it hooked up. Normally I wouldn't bitch about this kind of thing but up here being stuck in 2WD after a heavy snow sucks ass.
 
If directly effected by low temp, I'd lead towards the control panel, probably a cracked solder joint, it gets cold and the crack opens, you can open it up and look for a crack, or just hit all the joints with a soldering iron
 
dave89iroc said:
If directly effected by low temp, I'd lead towards the control panel, probably a cracked solder joint, it gets cold and the crack opens, you can open it up and look for a crack, or just hit all the joints with a soldering iron
Click to expand...

Only time it does that is when it's been REALLY cold. I have a heated garage and never is an issue unless I don't park in the garage, and at that it's only intermittent. I also noticed that there seems to be some kind of a motor noise coming from under the dash right after startup. Sounds like an ailing servo motor. Runs loudly for about a minute then shuts off. Also makes this noise whether or not the 4WD takes a dump or not.
 
Sounds like it could be the updog in the transfer case. Best case will be to get it on the scan tool like already mentioned and figure out what code it's throwing. A lot of times the switch can fail on these also.
 
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