88 Brake Warning Lamp (Red) Circuit

NAME OF CODE:
88 Brake Warning Lamp (Red) Circuit


SET CONDITION:
The following criteria must be met for this trouble code to be detected.

1. CAB microprocessor control software commanding the red brake system indicator lamp to be turned on.
a. During the bulb check at vehicle ignition turn "ON".
b. In response to any CAB microprocessor detected trouble condition that results in microprocessor controlled inhibiting of the ABS function.
2. High feedback voltage from the low side of the BRAKE warning lamp.
3. Criteria 1 and 2 satisfied for 10 consecutive checks spaced 5 ms apart.


POSSIBLE CAUSES:
- Anything that keeps brake system indicator lamp feedback voltage high when the red BRAKE warning lamp is supposed to be turned on
- Shorted to vehicle battery voltage in the wiring between the BRAKE warning lamp and the CAB.
- Open ABS warning lamp relay driver transistor in the CAB.
- Short to high voltage in the lamp feedback path within the CAB.