Automobile & Light Truck Certification Test A5 BrakesDisc Brake Diagnosis and RepairHard
A vehicle with an integrated electric parking brake (EPB) system requires rear brake pad replacement. After physically removing the caliper, what essential step must be performed using a scan tool before the pistons can be safely retracted?
- ABleed the rear brake lines.
- BReset the ABS warning light.
- CPlace the EPB into service mode.
- DCalibrate the new brake pads.
Show answer & explanationAnswer & explanation
Correct answer: C. Place the EPB into service mode.
Vehicles with electric parking brakes utilize an electric motor to extend and retract the caliper piston for parking brake engagement. Attempting to manually compress these pistons without placing the EPB into 'service mode' via a scan tool can damage the EPB motor, gears, or the caliper itself. Service mode retracts the piston electronically, allowing for manual compression or direct replacement.
Why the other options are wrong
- A. Bleeding the brake lines is done *after* pad replacement and piston retraction, not before, and doesn't affect piston retraction for EPB.
- B. Resetting the ABS light is typically done if a fault code was present, not as a standard step for EPB piston retraction.
- D. Calibrating new pads (e.g., bedding-in) is a post-service procedure, not a prerequisite for piston retraction.
Electric Parking Brake (EPB) Service Mode
Before servicing rear calipers with an integrated Electric Parking Brake (EPB) system, a scan tool must be used to place the EPB into service mode to safely retract the piston.
- Prevents damage to the EPB motor and caliper.
- Electronically retracts the piston.
- A critical step for vehicles with EPB.
Memory trick: EPB's electric, scan tool's the trick, for safe piston retraction, quick!