Conditions For Setting DTC
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.
System will set DTC when ATC control module detects voltage in circuit, sees a front or rear drive shaft speed signal, or vehicle speed signal from VCM or PCM over Class 2 data bus is 10 MPH or more for 10 consecutive seconds.
Whenever park/neutral is detected, control module input indicates transmission was in Park. All range shifts will be disabled. SERVICE 4WD light will be on for remainder of current ignition cycle.