ABS Light: Description and Operation

ABS WARNING INDICATOR
The amber ABS warning indicator is located in the instrument cluster. It is used to inform the driver that the antilock function has been turned off due to a system malfunction. The CAB controls the lamp indirectly. The CAB monitors its own functions. If the CAB determines that the ABS warning indicator should be on, the CAB sends a message via the PCI BUS to the instrument cluster and the cluster turns on the indicator. The indicator will remain lit during every key cycle until the circuit or component fault is repaired and the CAB no longer detects the fault. After repair of a sensor signal fault or a pump motor fault, the CAB must sense all four wheels at 25 km/h (15 mph) before it will extinguish the ABS and TRAC OFF Indicators.

The Instrument Cluster will illuminate the ABS Warning Indicator if it loses communication with the CAB.

When the ignition key is turned to the ON position, the amber ABS warning indicator lamp is lit until the Controller Antilock Brake (CAB) completes its self-tests and turns OFF the lamp (approximately 4 seconds). The amber ABS warning indicator lamp will illuminate when the CAB detects a condition that results in the shutdown of ABS function. The CAB sends a message to the Mechanical Instrument Cluster (MIC) instructing it to turn ON the amber ABS warning indicator lamp.

Under most conditions, when the amber ABS warning indicator lamp is ON, only the ABS function of the brake system is affected; The Electronic Brake Distribution (EBD), the base brake system and the ability to stop the vehicle are not affected.