Automatic Traction Control

Vehicles with electronic engines and ABS may have Automatic Traction Control (ATC). On these vehicles, the ATC system automatically limits wheel spin during reduced-traction situations. In normal braking applications, the standard air brake system is in effect.

During reduced-traction situations, the ATC solenoid valve controls air pressure to the modulator valves and they in turn increase, hold, or reduce pressure to the appropriate brake chambers to provide better traction whenever wheel spin occurs.

When the ATC system is in the NORMAL mode, it will apply gentle braking to the spinning wheel, to feed power to the wheel(s) with better traction. If both wheels are spinning, the system will signal the engine to reduce power.

ATC may include a deep snow and mud option to increase available traction on extra soft surfaces like snow, mud, or gravel. If so equipped, a momentary contact rocker switch labeled ATC will be located on the dash. Pressing the switch will temporarily allow more wheel spin. The activation of the deep snow and mud option is indicated by a flashing WHEEL SPIN lamp. Pressing the switch again will cycle the system back to normal operation.

After the ignition switch is turned on, the ABS indicator light and the WHEEL SPIN indicator light illuminate for about three seconds. After three seconds, the warning lights go out if all of the ABS components are working.

During vehicle operation, solid illumination of the ABS light indicates a problem with the vehicle ABS. Repair the ABS immediately to ensure full braking capability.

If equipped with ATC, an amber WHEEL SPIN indicator light illuminates if one of the drive wheels spins during acceleration. When the light illuminates, partially release the throttle pedal to stop the spinning wheel. The light goes out when the wheel stops spinning.

If slippery road conditions continue, turn on the differential lock switch. See Drive Axles With Differential Lock for axle switch instructions.