ASE G1 Auto Maintenance and Light RepairBrakesHard
A vehicle with an electronic parking brake (EPB) system has a warning light illuminated on the dashboard. The owner reports that the parking brake sometimes fails to engage or disengage. The technician connects a scan tool and finds a DTC indicating a 'Parking Brake Motor Circuit Malfunction'. What is the MOST likely cause?
- AWorn rear brake pads
- BA fault within the EPB caliper motor or its wiring
- CA low brake fluid level
- DA stretched parking brake cable
Show answer & explanationAnswer & explanation
Correct answer: B. A fault within the EPB caliper motor or its wiring
An 'Electronic Parking Brake (EPB) Motor Circuit Malfunction' code directly points to an electrical issue with the motor that operates the EPB caliper, or the wiring that connects to it. EPB systems use an electric motor to actuate the parking brake, and a circuit malfunction indicates a problem with that specific motor or its electrical supply/signal.
Why the other options are wrong
- A. While worn rear brake pads can affect parking brake effectiveness over time, they would not directly cause an 'EPB Motor Circuit Malfunction' DTC.
- C. Low brake fluid typically triggers a general brake warning light, not a specific EPB motor circuit malfunction code.
- D. A stretched parking brake cable applies to traditional cable-actuated parking brakes, not EPB systems which use electric motors at the calipers.
Electronic Parking Brake (EPB) Motor Circuit Malfunction
A diagnostic trouble code indicating an electrical fault with the motor or wiring responsible for actuating an electronic parking brake caliper.
- EPB systems use electric motors at the calipers, not cables.
- The fault points to an issue with the motor's power supply, ground, or control signal.
- Requires electrical testing of the motor and its associated wiring harness.
Memory trick: EPB motor circuit fault means the electric gears aren't turning.