Why is my emergency brake not holding?
The parking brake not holding is usually caused by worn or misadjusted components, a stretched or seized cable, binding from rust, or a fault in an electronic parking brake (EPB) system. The exact fix depends on whether your car uses a mechanical or an electronic parking brake.
When a parking brake fails to hold, it can indicate a problem in the rear braking system or in the mechanism that engages it. This article outlines common causes, how to diagnose safely, and practical steps to address the issue. It covers both traditional mechanical cables and modern electronic parking brakes, as well as when to seek professional service and how to prevent recurrence.
Quick checks and safety steps
Before diving into fixes, perform these quick checks to gauge the issue and stay safe. If the vehicle moves or you notice fluid leaks or excessive heat after parking, stop and get professional help.
- The car should be on level ground and secured with wheel chocks before any inspection.
- Note whether the lever or switch feels loose, sticks, or requires unusual force to engage or release.
- Check for any warning lights related to the parking brake or brake system.
- Look for signs of contamination (oil, brake fluid) on the rear drums/shoes or pads.
- Feel for unusual heat on the rear wheels after the vehicle has been parked for a while; excessive heat can indicate a stuck brake.
These quick checks help you determine whether you can safely proceed with a basic inspection or if you should stop and contact a professional.
Common causes for not holding
- Worn or misadjusted parking brake shoes/pads
- Parking brake cable stretched or seized
- Rust, corrosion, or binding in rear calipers or drums
- Parking brake lever or electric actuator failing to engage or release
Addressing these issues often involves inspection of the rear brakes and the parking brake mechanism, followed by replacement or adjustment as needed. If the fault is electronic, diagnostics with the appropriate tool are usually required to pinpoint the exact code or component failure.
How to diagnose safely
Use these steps to diagnose the root cause. Always prioritize safety and consult your owner’s manual for model-specific guidance, especially for EPB systems.
- Identify the system type: mechanical (cable) parking brake or electronic (EPB).
- Inspect rear wheels for obvious signs of wear, contamination, or stuck components (drums, shoes, pads, calipers).
- Check the parking brake cable for fraying, rust, or stiffness. At accessible points, try moving the cable by hand gently to feel for smooth movement.
- For mechanical systems, remove the rear drums (or access the shoes) to inspect wear on shoes/pads and to check the adjuster for proper tension.
- Test the system: engage the parking brake and attempt to move the vehicle on a safe incline (in a controlled environment). Note how much force is required and whether the car remains stationary.
- Look for signs of fluid leaks or oil contamination on the shoes or pads; replace contaminated components if found.
- If you have an EPB, check for fault codes with an appropriate diagnostic tool, inspect the battery state of charge, and verify fuses related to the EPB system.
After completing these checks, you should have a clearer sense of whether the issue is purely mechanical, electrical, or related to contamination or wear. If any step reveals a potentially dangerous condition (car moves unexpectedly, excessive heat, or inability to engage), seek professional service immediately.
Troubleshooting by system type
Mechanical (cable-based) parking brakes
These systems rely on a cable connected to rear brake assemblies. The most common failures are wear, stretching, and improper adjustment. Follow these steps to address a mechanical system:
- Inspect the parking brake cable for fraying, corrosion, or kinks. Replace if damaged.
- Check the rear brake shoes/pads for wear; replace worn components and inspect for signs of oil contamination.
- Ensure the cable tension is correct. Many vehicles have an access point at the rear brakes to adjust tension. Refer to the service manual for the correct procedure and torque specs.
- After adjustment, test the system by applying the brake and attempting to move the car slowly on a gentle incline. The car should be held securely without excessive lever force.
- Reassemble and recheck for smooth operation, ensuring there are no rubbing noises when the brakes are released.
If the rear drums are out of round or the calipers are sticking, replacement of the worn parts or caliper service may be required. Regular inspection helps prevent this issue from recurring.
Electronic parking brake (EPB)
EPB systems use electric motors and control modules to actuate the rear brakes. Common causes include electrical faults, battery issues, and software/calibration problems. Follow these steps if you have EPB:
- Check fuses and the battery: a weak battery can prevent the EPB from holding or releasing properly.
- Read fault codes with a suitable OBD-II scanner or the manufacturer’s diagnostic tool. Note any EPB-related codes.
- Listen for the EPB motor when engaging the brake; a lack of motor activity or abnormal noises can indicate actuator failure.
- If codes point to calibration or module issues, the system may need a reset or software update performed by a dealer or qualified shop.
- If the caliper motor or actuator is physically stuck or damaged, replacement is usually required.
EPB issues often require professional diagnostics and recalibration. Do not attempt to force a stuck EPB, as this can damage the braking system or wiring.
When to seek professional service
Call for professional help if you notice any of the following: the vehicle moves unexpectedly when parked, the parking brake cannot be released, you hear grinding or burning smells, or warning lights indicate a brake fault. Complex EPB issues, persistent sticking, or rear brake contamination also call for a trained technician.
Prevention and maintenance tips
- Use the parking brake regularly, especially in damp or humid conditions, to prevent cables from seizing.
- Have the rear brakes inspected during routine service, and replace shoes/pads in pairs as recommended by the manufacturer.
- Inspect for oil leaks that could contaminate brake shoes or drums and address leaks promptly.
- Keep the EPB system healthy by ensuring the 12V battery is in good condition and the vehicle’s electrical system is clean and free of corrosion.
- Avoid over-tensioning the cable during adjustments and follow manufacturer guidelines to prevent cable wear or fraying.
Preventive maintenance reduces the likelihood of a parking brake failure and helps ensure the system engages reliably when needed.
Summary
A parking brake that won’t hold is usually caused by wear, misadjustment, binding, or a fault in the electronic system. Start with a safety-focused assessment, then identify whether your car uses a mechanical cable or an EPB. Inspect rear shoes/pads, cables, and calipers or drums for wear and contamination, and check for fault codes if you have EPB. Depending on the diagnosis, you may simply need an adjustment or a component replacement. If you’re unsure or the problem involves electrical diagnostics, seek professional assistance. Regular maintenance and proper use of the parking brake help prevent future failures.
What is the most common cause of parking brake failure?
Worn Out or Stretched Brake Cables
One of the most common reasons for a parking brake failure is a worn or stretched cable. Over time, the cable that connects the parking brake lever to the brakes can become frayed or stretched, leading to a lack of tension.
How to fix a loose emergency brake?
Clean and lubricate the threads on the cable adjuster. Back off the cable adjuster nut on the passenger side at the vehicle's midpoint or beside the parking brake lever. Loosen the adjustment so there is slack in the cable. Finally, tighten the nut until you feel a slight drag on the rear wheels.
How do you fix a parking brake that won't hold?
A few things to check:
- Check the parking brake cables for any kinks, cracks or damage from being suddenly released under load.
- Check where the parking brake lever connects to the cables.
- Check condition of the parking brake shoes/pads.
- Check parking brake adjustment at each wheel cylinder/caliper.
Why isn't my handbrake holding?
Common Reasons Your Handbrake Isn't Holding
If you notice your handbrake lever pulls up higher than usual or feels loose, worn shoes or pads might be the culprit. The handbrake cable can stretch or weaken over time, especially in colder climates where moisture and road salt contribute to corrosion.
