Automobile & Light Truck Certification Test A5 BrakesDrum Brake Diagnosis and RepairEasy
A vehicle's parking brake does not hold the vehicle on an incline, and the parking brake lever feels loose with excessive travel. The technician confirms that the parking brake cables are not seized and the internal drum brake components appear to be in good condition. What is the MOST likely cause of this issue?
- AInsufficient tension in the parking brake cable.
- BWorn or glazed service brake shoes.
- CA faulty master cylinder.
- DA leaking wheel cylinder.
Show answer & explanationAnswer & explanation
Correct answer: A. Insufficient tension in the parking brake cable.
A loose parking brake lever with excessive travel and poor holding power, when cables are not seized and internal components are good, strongly points to insufficient tension in the parking brake cable. This cable needs to be adjusted to take up the slack.
Why the other options are wrong
- B. While worn shoes contribute to poor holding, the 'loose lever with excessive travel' specifically indicates cable tension.
- C. A faulty master cylinder affects the service brakes, not primarily the mechanical parking brake.
- D. A leaking wheel cylinder affects service brakes and would not directly cause a loose parking brake lever.
Parking Brake Cable Adjustment
The process of setting the correct tension in the parking brake cable to ensure proper engagement and holding power with appropriate lever travel.
- Prevents excessive lever travel.
- Ensures adequate holding force.
- Performed at the equalizer or cable ends.
Memory trick: Cable too loose, parking's no use, adjust the noose.