Red Brake Warning Lamp

Symptom: The red brake warning lamp stays on after the initial bulb check.

POSSIBLE CAUSES: Parking brake applied, malfunctioning parking brake switch, wiring; Low brake fluid level, malfunctioning fluid level sensor; Loosen or damaged connectors or wiring; Low accumulator pressure; Faulty lamp driver module.

INSPECT

1. Turn ignition off.
2. Properly connect 94-00101-A to vehicle.
3. Turn ignition on. Using 94-00101-A, read brake pressure.
4. If brake pressure is OK, [12,411 kPa (1800 psi) or greater], go to step 5. If brake pressure is low, perform test (D) "Low Or No Boost Pressure". (D) Low or No Boost Pressure
5. Disconnect brake fluid level sensor connector from the Powermaster III. Does lamp go out? If yes, check for low brake fluid or faulty low fluid level sensor or switch.
6. If the red brake warning lamp is still on, apply and fully release the parking brake. If the lamp remains on, inspect the parking brake switch, wiring and connectors.
7. If lamp is still on, locate and unplug lamp driver module. Verify lamp driver module input is ground. If so, and lamp goes out, replace lamp driver module. If OK, check low fluid sensor wiring and ignition switch bulb test circuit for short to ground.