ABS Warning Lamp

PURPOSE
The EBC-5H system is equipped with an amber Anti-Lock Brake System (ABS) warning lamp to alert the driver of a malfunction it has detected.

OPERATION
The Controller - Antilock Brake (CAB) completes the light circuit through pin 13 in the CAB 37- way connector.

The CAB completes the circuit for the ABS warning light by providing a ground. It operates the light by making it do one of two things:
- Light steady for 3.4 seconds during an initial test at the beginning of an ignition cycle
- Light steady when a system malfunction exists

An input monitor circuit within the CAB allows it to detect an open or short circuit for the ABS warning light during the initial test for each ignition cycle. When the ABS lamp is lit, the voltage at the monitoring point within the CAB will be 0 volts. The voltage at the monitor point will be 12 volts when the CAB energizes the relay turning the ABS lamp off.

If the CAB monitors 12 volts at pin 13 before it attempts to go high, it determines that a short or open exists. The CAB will take diagnostic action by illuminating the red brake lamp to alert the driver and storing the (89) Indicator Lamp Circuit Failure trouble code. This trouble condition does not in itself cause the antilock system to be inhibited; some other condition is also required.