ASE G1 Auto Maintenance and Light RepairElectrical/Electronic SystemsMedium
A vehicle owner reports that their dashboard 'BRAKE' warning light remains illuminated even after releasing the parking brake and checking the brake fluid level, which is full. What is the MOST likely cause?
- AA faulty brake light switch.
- BA stuck parking brake switch.
- CA faulty ABS wheel speed sensor.
- DWorn brake pads.
Show answer & explanationAnswer & explanation
Correct answer: B. A stuck parking brake switch.
The 'BRAKE' warning light typically illuminates for two primary reasons: low brake fluid or an engaged parking brake. Since the brake fluid level is full and the parking brake is released, the most direct cause for the light remaining on is that the parking brake switch is stuck in the 'ON' position, signaling the light to stay illuminated even though the brake is disengaged.
Why the other options are wrong
- A. A faulty brake light switch controls the brake lights at the rear of the vehicle, not the dashboard 'BRAKE' warning light.
- C. A faulty ABS wheel speed sensor would typically illuminate the 'ABS' warning light, and possibly the 'Traction Control' light, not the primary 'BRAKE' warning light.
- D. Worn brake pads can sometimes trigger a separate 'brake wear' indicator light (if equipped) or cause a low brake fluid level (as calipers extend), but not directly the primary 'BRAKE' warning light if fluid is full.
Brake Warning Light Triggers
The dashboard 'BRAKE' warning light is primarily triggered by low brake fluid level or an engaged parking brake.
- A float switch in the master cylinder reservoir detects low fluid.
- A switch at the parking brake lever/pedal detects engagement.
- Other brake system issues (like ABS faults) have their own dedicated warning lights.
Memory trick: Brake light's on, fluid's good, parking brake's misunderstood.