Anti-Lock Brake System/Traction Control System: Operation

The Delphi DBC 7 Anti-Lock Brake System/Traction Control (ABS/TCS) minimizes wheel slip during heavy braking. ABS control module monitors speed of each wheel and controls brake fluid pressure to each wheel independently during a braking event, allowing driver to maintain directional stability while minimizing stopping distance. The ABS control module performs a continuous diagnostic routine to detect malfunctions. If module detects an electrical malfunction, it can disable the ABS/TCS or the Dynamic Rear Proportioning (DRP). The DRP is an electronic brake proportioning feature that replaces the mechanical proportioning valve in the base brake system. DRP uses ABS components to regulate vehicle rear brake pressure and provide optimum front-to-rear brake balance in all braking situation.

The Traction Control System (TCS) compares front wheel speed to rear wheel speed to determine if drive wheel loose traction. TCS activates when drive wheel speed exceeds speed on non-drive wheels by a calibrated value. This allows driver to maintain acceleration and directional stability while accelerating on low traction surfaces. TCS limits wheel slip during acceleration when one or more of drive wheels lose traction. During a TCS event, PCM controls wheel slip using a combination of spark timing retard, transmission upshift (A/T only) and fuel injector reduction. PCM disables TCS if traction control switch is depressed, ABS control module indicates wheel speed errors, there is a loss of serial data between ABS control module and PCM, and certain PCM DTCs are set. TCS does not use brake intervention to control wheel slip.