Traction Control System (TCS) Description

TRACTION CONTROL SYSTEM (TCS) DESCRIPTION (IF EQUIPPED)
The main purpose of traction control is to reduce wheel slip and maintain traction at the driven wheels when road surfaces are slippery. The traction control system reduces wheel slip by braking the wheel that is losing traction. The system is designed to operate at speeds below 56 km/h (35 mph).

TRACTION CONTROL OPERATION (IF EQUIPPED)
The Anti-lock Brake Module (ABM) monitors wheel speeds. If, during acceleration, the module detects front (drive) wheel slip and the brakes are not applied, the ABM will enter traction control mode. Traction control works in the following order when drive wheel slip is detected.
1. Close the (normally open) isolation valves.
2. Start pump/motor and supply volume/pressure to front hydraulic circuits (pump runs continuously during traction control).
3. Open and close build and decay valves to maintain minimum wheel slip and maximum traction.

The cycling of the build and decay valves is similar to the ABS except that they work to control wheel spin by applying brakes. ABS function is to control wheel skid by releasing brakes.

Two pressure relief valves allow excess fluid volume to return to the reservoir when not used by the build/decay cycles. These are required because the pump supplies more volume than the traction control system requires.

If at any time the brake pedal is applied during a traction control cycle, the brake lamp switch will trigger the ABM to switch off the traction control.

The traction control system will be enabled at each ignition cycle. It may be turned off by depressing the Traction Control Switch. The traction control system function lamp will illuminate Traction Control immediately upon depressing the traction control switch button. The indicator will illuminate during a traction control event.

If the ABM calculates that the brake temperatures are high, the traction control system will become inoperative until a time-out period has elapsed. When in this thermal protection mode, the traction control indicator will illuminate; however, a fault will not be registered.

TRACTION CONTROL FUNCTION LAMPS

The traction control function lamp illuminates during a traction control cycle.

The traction control system is enabled at each ignition cycle. It may be turned off by depressing the traction control switch button. The traction control function lamp illuminates immediately upon depressing the button.

If the ABM calculates that the brake temperatures are high, the traction control system becomes inoperative until a time-out period has elapsed. During this "thermo-protection mode", the traction control function lamp illuminates; note that no trouble code is registered.

In the event that a system fault occurs thus illuminating the ABS warning indicator lamp, the traction control function lamp will also illuminate.
CAUTION: The ABS uses an electronic control module, the ABM. This module is designed to withstand normal current draws associated with vehicle operation. Care must be taken to avoid overloading the ABM circuits.