Traction Control General Description

PREVENTING WHEEL SPIN DURING ACCELERATION
Traction Control System (TCS) is designed to prevent wheels from spinning excessively during acceleration. The system operates at all vehicle speeds, and reduces wheel slip by braking the wheel which is losing traction. A primary difference between the traction control mode and the antilock braking mode is that brake fluid pressure is increased to lessen wheel spin during traction control, but is reduced during antilock braking to enable greater wheel spin. A normal characteristic of traction control system includes initialization noise the same as the ABS.

REDUCING TORQUE TO THE DRIVING WHEELS
Traction control will not have any effect on the operation of the vehicle until the control module detects one or both of the front wheels rotating faster than the rear wheels. At this time the Electronic Brake Traction Control Module (EBTCM) will request the Powertrain Control Module (PCM) to reduce the amount of torque applied to the drive wheels.

Retarding Timing and Braking Front Wheels
The PCM does this by retarding timing, turning off the supercharger, and the fuel injectors. The EBTCM will apply the front brakes, thus reducing torque to the front wheels. Once the front wheels begin to rotate at the same speed as the rear wheels, the system will return full control to the driver.

Directing Torque
During Traction Control mode, if the brake is applied to only one front wheel, most of the torque from the engine will be directed to the other front wheel which will improve the traction of the vehicle.

Master Cylinder Isolation
The braking is accomplished by closing the TCS master cylinder isolating valves; this isolates the master cylinder from the rest of the system. The TCS prime valves open to allow the pump to get brake fluid to build pressure for braking. The drive wheel circuit solenoids are energized as needed to allow for pressure hold, pressure increase, or pressure decrease.

SYSTEM DEACTIVATION
The TCS may be deactivated by the driver if desired. In order to deactivate the TCS with the engine running, depress the Traction Control disable switch. This will cause the "TRACTION OFF" lamp in the instrument cluster to illuminate. The system will remain deactivated until the ignition switch is cycled, or the switch is pressed again.

NOTE: The Speed Dependent Steering System (MAGNASTEER) (TM) incorporates its controller into the EBCM/EBTCM. MAGNASTEER Diagnostic Trouble Code (DTC) C1241 will not cause the "ABS" or "TRACTION OFF" indicators to turn "ON."