Service 4WD Light Stays On When Key Is On
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 1998 GMC Yukon, 1998 GMC Suburban, 1998 GMC Pickup, 1998 GMC Cab & Chassis, and 1998 Chevrolet Tahoe. However, it is still accessible from the selected car via links, so may be relevant.
- If ATC system check was performed, go to next step. If system check was not performed, see ATC SYSTEM CHECK .
- Connect scan tool to DLC. Turn ignition to run position (engine off). Using scan tool, command SERVICE 4WD light off. If light goes off, go to next step. If light does not go off, go to step 4).
- Replace ATC control module. See REMOVAL & INSTALLATION . When replacement is complete, see ATC SYSTEM CHECK .
- Turn ignition off. Disconnect ATC control module connectors C1 and C2. Turn ignition to run position (engine off). If light is off, go to step 3). If light is on, go to next step.
- Locate and repair short to ground in Light Blue/Black wire between SERVICE 4WD light and ATC control module. When repair is complete, see ATC SYSTEM CHECK .