Normal Operation

Traction control utilizes ABS components to detect and control excessive rear wheel spin on low-traction surfaces. On high-traction surfaces, traction control will permit a controlled amount of rear wheel spin in the interest of quick acceleration. The traction control strategy will utilize throttle position information provided by the PCM over the High Speed Controller Area Network (HS-CAN) and front wheel speed sensor input to determine if it is necessary for traction control to intervene.

If the rear wheels begin to spin on a low-traction surface, the ABS module will use the Hydraulic Control Unit (HCU) to modulate brake fluid pressure to the rear brake calipers. At the same time, the ABS module sends a message to the PCM over the HS-CAN bus to modulate engine torque. Engine torque modulation is achieved by regulating fuel and spark to the cylinders. Once the rear wheels return to the desired speed, the ABS module stops modulating the brake fluid pressure and stops sending the message to the PCM.

This pinpoint test is intended to diagnose the following:

• Wiring, terminals or connectors
• Instrument cluster
• ABS module