RAM 2500 Truck 4WD V8-5.9L VIN Z LDC (1998)
ABS Light: Description and Operation
General Information
SYSTEM OPERATION
The Anti-Lock Brake System (ABS) lamp gives an indication when the ABS system is faulty or inoperative. The lamp is controlled by the
instrument cluster circuitry based upon messages received from the Controller Anti-lock Brake (CAB) on the Chrysler Collision Detection (CCD)
data bus. The lamp is turned on by the CAB for about two seconds when the ignition switch is turned to the On position as a bulb test.
After the bulb test, the CAB turns the lamp on or off based upon the results of the ABS self-tests. The CAB continually monitors the ABS circuits
and sensors to decide whether the system is in good operating condition. The CAB then sends the proper messages to the instrument cluster on the
CCD data bus to turn the lamp on or off. If the CAB turns the lamp on after the bulb test, it indicates that the CAB has detected a system
malfunction and/or that the ABS system has become inoperative. If only the amber ABS lamp is illuminated, and the red brake warning lamp
remains off, the base brake system will operate normally.
Each time the instrument cluster circuitry receives a lamp-on message from the CAB, it will light the lamp for the duration of the ABS
malfunction. The CAB will also flash this lamp during the diagnostic mode, unless a hard fault is present. If a hard fault is present, the ABS lamp
will illuminate without flashing.
