Traction Control General Description

TRACTION CONTROL COMPONENTS
The traction control system is composed of the traction enable switch with LED, traction active lamp, ABS wheel speed sensors, ABS controller, and the PCM's control of spark timing, fuel injectors and transaxle upshift.

OPERATION
Overview
The PCM monitors the wheel slip and the status of the traction switch. The data is received from the ABS controller. When traction is in the enable mode (switch on) and the PCM sees wheel slip of 1 km/h (0.5 mph) during cruising or 3 km/h (2 mph) during launch, the PCM begins to retard the spark timing to limit torque to the wheels. If wheel slip continues the PCM will command a transaxle upshift one gear at a time until fourth gear is reached. If slip is still present, the PCM will reduce the authority of the spark system, and control slip by toggling the fuel injectors on and off.

PCM Interaction With Traction Control
The PCM is the "master" of the traction control system receiving inputs on Traction Control switch and wheel speed status from the ABS controller. The PCM looks at this data then verifies no Engine Control/Transmission Control codes are present and commands the ABS controller to turn on the traction LED, indicating traction control system is enabled. The PCM will disable the traction control system under the following conditions:
^ The driver presses the Traction Control switch, requesting Off.
^ The ABS controller has indicated wheel speed sensor problems to the PCM. (One of diagnostic trouble codes 21-28 is set).
^ No serial data communication between the PCM and ABS controller. Certain PCM codes are set.

ABS Controller Interaction With Traction Control
The ABS controller takes the average of the two front wheel speeds minus the average of the two rear speed sensor inputs and calculates wheel slip. It then determines the status of the Traction Control switch and communicates this data to the PCM initiating spark control. The ABS controller also turns the Traction Control LED On or Off depending on the command from the PCM.

TRACTION CONTROL USE WITH CHAINS OR SPARE TIRE
The traction control system can be used with chains or the spare tire. The traction control system can be turned Off for improved vehicle launch while using chains.

OPTION BIT STATUS
Traction control vehicles must be programmed with the correct options in both the PCM and the ABS controller for proper system operation.