Service 4 WD light is on

mustafade · April 11, 2005

Any one has exprince this problem with their truck "Service 4WD" light comes on, on the massage center. What couses that and how to fix it without taking to the dealership.

Thanks,

Mustafa

silverado man · April 11, 2005

http://www.gm-trucks.com/forums/index.php?showtopic=40590It is more than likely the 4wd switch on the dash. See this thread for part number.

2003yukonxl2500 · April 11, 2005

Mine does the same thing from time to time. If I shut the vehicle off and back on it resets.

-Jeff

99silveradoz71 · April 12, 2005

Mine came and went as well when it ended up being the switch.

roden001 · April 12, 2005

Based on the following info from my service tech CD's, I pulled a fuse under the hood, waited 30 seconds, put it back in, and the message went away when I cranked the truck again. Hasn't come back, and that was six weeks ago. Apparently, if the problem is recurrent, you have to go on and have that reprogramming done (described below).

Or, it could be the switch failing, like everyone agrees is very common.

Adm Msg - Inoperative 4WD/AWD or Service 4WD Indicator (Admin Number VSS20020131 10/4/02) #VSS20020131 - (Oct 4, 2002)

Adm Msg -- Inoperative 4WD/AWD or Service 4WD Indicator (Admin Number VSS20020131 -- 10/04/02)

Chevrolet Silverado, Tahoe, Suburban, Avalanche, TrailBlazer, TrailBlazer EXT; GMC Sierra, Yukon, Yukon XL, Envoy, Envoy XL; Oldsmobile Bravada

With RPO Codes: NP8 - Autotrack Transfer Case; NP4 - Autotrack Transfer Case; NP1 - Electric Shift Transfer Case

Important

Corporate Bulletin Number 02-04-21-006A will supersede this message.

Customer Concern

Some customers may comment that the service 4WD indicator is on, or the 4WD system is inoperative.

Cause

The Transfer Case Control Module (TCCM) has not received the wake-up call during key-up and has remained in the "sleep mode." When the TCCM is in the "sleep mode," it will not communicate with the class II bus or the Tech 2.

Correction

Remove the underhood TCCM fuse (labeled ATCM or TREC). Wait 30 seconds and then reinstall the fuse. The module should "wake up" and communicate with the Tech 2. Reprogram the TCCM using normal SPS procedures, using operating system calibration number 12580062 (or the most current calibration).