Chevrolet, GMC Warning Message
“Service 4WD”
The four-wheel drive or all-wheel drive system has detected a fault. The transfer case, front axle disconnect, or electronic shift module may not be functioning correctly.
moderate severity
Common Causes
- Transfer case encoder motor failure
- Front axle disconnect actuator fault
- Transfer case fluid degradation
- TCCM (Transfer Case Control Module) fault
- Wiring harness corrosion
Immediate Action
The vehicle may default to 2WD. Drivable on paved roads. Avoid off-road or severe weather conditions until repaired.
Typical Repair Cost
$300–$2,500