Anti-Lock Control

Anti-Lock Control





The Anti-Lock Brake System (ABS) modulates brake pressure on each wheel independently to maintain vehicle stability during braking. The ABS continually monitors the rotational velocity of each wheel anytime the ignition switch is in the RUN position and determines if a tire is loosing traction when the brakes are applied. Only then does the ABS intervene to modulate the brake pressure to the necessary wheel. The modulation continues until the wheel rotates freely. The brake pressure is then restored and the modulate/restore cycle is repeated whenever loss of traction is detected. This cycle occurs at a rate of several times per second.
The ABS module is capable of detecting the following system conditions
- Hydraulic valve failure
- Wheel speed sensor failure
- ABS power relay short circuit
- Interconnect failures to the ABS sensors, power and ground to the ABS module
- Over/under voltage conditions
The ABS provides self-diagnostics and displays failure messages, via the ABS indicator, in the instrument cluster. Failure of the ABS module, for whatever reason, will not compromise the normal operation of the brake system.
Dynamic Stability Control (DSC) maximizes vehicle stability under all conditions. The DSC system compares actual vehicle course to that intended by the driver. If the intended course differs from the actual course due to over steer or under steer conditions, the DSC system will brake individual wheels and reduce engine torque to bring the vehicle back to the driver's intended direction. By using a combined yaw rate sensor and lateral accelerometer, the vehicles rotational motion around its vertical axis and centrifugal forces generated while cornering are calculated to determine the vehicle's actual behavior. Using additional sensors for detecting steering wheel position and road wheel speed enables the system to recognize the driver's intentions.
Traction control is an additional function added to the DSC system. The vehicles driven wheels are continually monitored for wheel spin relative to the calculated reference speed and to each other. If wheel spin is detected, the traction control function intervenes independently of the driver, applying brake pressure to the slipping wheel and reducing the engine drive torque supply. Meanwhile, brake pressure is modulated by the traction control until traction is re-established. Traction control brake actuation is diminished above 25 mph. Above this speed traction control relies primarily on engine torque reduction.
Dynamic stability control is enabled/disabled via the DSC "ON/OFF" switch. When the switch is in the "OFF" position, the amber DSC warning lamp solidly illuminates within the instrument cluster message center. The DSC is automatically activated when the ignition is switched on. The DSC provides self-diagnostics also via the instrument cluster message center.
The traction control brake intervention is automatically disabled whenever the brakes exceed a temperature limit. The traction brake intervention will remain disabled until the brakes have cooled, irrespective of ignition switch position or ignition switch cycling.