Traction Control System

The traction control system (TCS) utilizes the active braking controls in the ABS and the engine torque reduction function of the engine management system to prevent longitudinal wheel spin during vehicle acceleration.

When drive wheel slip is noted while the brake is not applied, the EBCM will enter traction control mode.

First, the EBCM requests the ECM to reduce the amount of torque to the drive wheels via the requested torque signal circuit. The ECM reduces torque to the drive wheels by retarding spark timing and turning off fuel injectors. The ECM reports the amount torque delivered to the drive wheels via the delivered torque signal circuit.

If the engine torque reduction does not abolish drive wheel slip, the EBCM will actively apply the drive wheel brakes. During traction control braking, hydraulic pressure in each drive wheel circuit is controlled to prevent the drive wheels from slipping. The master cylinder isolation valve closes in order to isolate the master cylinder from the rest of the hydraulic system. The prime valve then opens in order to allow the pump to accumulate brake fluid in order to build hydraulic pressure for braking. The drive wheel inlet and outlet solenoid valves then open and close in order to perform the following functions:

• Pressure increase
• Pressure hold
• Pressure decrease

If at any time during TCS mode the brakes are manually applied, the EBCM will exit the TCS brake intervention mode and allow for manual braking.