Automobile & Light Truck Certification Test A5 BrakesDrum Brake Diagnosis and RepairMedium
A vehicle owner complains that their parking brake does not hold the vehicle on a slight incline, even when fully engaged. A technician inspects the rear drum brakes and finds that the parking brake levers on both sides are seized in the 'off' position. What is the MOST appropriate diagnostic step to take next?
- ADisassemble the drum brake assemblies to free and lubricate the parking brake levers.
- BCheck for proper operation of the service brake system, as a fault there might affect the parking brake.
- CAdjust the parking brake cable tension at the equalizer.
- DReplace the parking brake cables, as they are likely stretched and worn.
Show answer & explanationAnswer & explanation
Correct answer: A. Disassemble the drum brake assemblies to free and lubricate the parking brake levers.
If the parking brake levers inside the drum are seized in the 'off' position, they cannot activate the shoes to hold the vehicle. The next logical step is to address this identified issue directly by disassembling and servicing the levers, which often involves cleaning and lubricating them.
Why the other options are wrong
- B. While related, the immediate problem is the seized parking brake levers themselves, directly preventing parking brake function.
- C. Adjusting cable tension won't free seized levers; it will only increase tension on a non-moving part.
- D. Cables might be fine; the issue is the seized levers preventing shoe activation.
Seized Parking Brake Levers (Drum)
Internal parking brake levers in drum brakes can seize due to corrosion or lack of lubrication, preventing the parking brake shoes from being activated.
- Prevents parking brake engagement.
- Common cause is rust/dirt.
- Requires disassembly for service.
Memory trick: Lever stuck, parking's luck, no hold, just muck.