Traction Control System

TRACTION CONTROL SYSTEM

The traction control (TC) system is used only on vehicles containing ABS. 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. The PCM monitors the wheel slip, as communicated by the ABS. The data is received from the ABS controller. When traction is in the enable mode (switch On) and the PCM senses wheel slip of 0.8 km/h (0.5 mph) during cruising or 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 (A/T) 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.


TRACTION CONTROL SWITCH

The traction control switch is a momentary contact switch read by the ABS controller, with the ABS also controlling the status of the LED. When the light is On, traction system is enabled and with the light Off, the traction system is disabled. At engine start, (no malfunctions present) traction control system is enabled regardless of previous switch state and the ABS controller illuminates the TC LED. The ABS controller continues to monitor TC switch for a change in state. If traction control is disabled for any reason other than driver input (turning switch Off), the LED will be turned Off and the malfunction indicator lamp or ABS telltale will be turned On to indicate malfunction. At this time the ABS controller will store switch status as being On although system and LED are Off. This is to prevent repeated toggling of the TC switch leaving switch status in Off when traction control becomes available again. If the malfunction goes away, the TC LED will light and the TC system will be enabled.


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 TC switch and communicates this data to the PCM initiating spark control. The ABS controller also turns the TC LED On or Off depending on the command from the PCM.


TRACTION ACTIVE TELLTALE

The traction active telltale is located in the instrument panel cluster. When the traction control system attempts to prevent wheel slip, the traction active telltale will begin to flash. This indicates traction system is currently working. Traction Active telltale is controlled by the ABS when the PCM communicates to the ABS, indicating traction control is active.

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 in both the PCM and the ABS controller for proper system operation.