What causes electronic parking brake to malfunction?
The most common causes are electrical faults (power and wiring), mechanical binding or actuator problems, and software or sensor faults.
In practice, failures can stem from a weak 12-volt battery or poor electrical connections, a seized actuator or caliper, worn or misaligned pads, or faulty control software and sensors that guide the system’s engagement or release. Environmental conditions, corrosion, and aging components can contribute as well.
Electrical faults and power supply
Electrical issues that deprive the EPB system of clean power or reliable signaling are frequent sources of failure. The following items cover typical electrical culprits.
- Weak or dying 12-volt battery or voltage drop under load
- Blown fuse or failing relay for the EPB control circuit
- Damaged, corroded, or loose wiring and poor grounding in the EPB harness or control module
- Faulty CAN bus communication or control-module failure affecting the EPB
- Moisture ingress or water damage to connectors and modules
Electrical faults are often identified by warning codes or fault lamps in the instrument cluster; addressing power delivery and communications can restore normal operation in many cases.
Mechanical and hardware issues
Mechanical problems with the EPB’s actuator, caliper, or linkage can prevent proper engagement or retraction. The following issues are commonly observed:
- Seized or corroded EPB actuator or caliper pistons preventing movement
- Sticking or seized brake calipers causing drag or jam
- Worn, contaminated, or misaligned brake pads or rotors affecting clearance
- Debris, ice, or snow obstructing the EPB mechanism
- Overheating or motor stall from heavy or prolonged use without service
Mechanical faults may require actuator or caliper replacement, cleaning, or re-alignment to restore function.
Software, sensors, and controls
Many EPB systems rely on electronic control units and a network of sensors. Software glitches or sensor faults can mislead the system about its state. Common software/sensor issues include:
- Faulty or outdated EPB control module firmware or software bugs
- Sensor faults (parking brake position sensor, wheel speed sensor, brake pedal switch) causing incorrect status signals
- Incorrect calibration after battery removal, module replacement, or service
- CAN bus communication errors disrupting command and feedback loops
Software updates and proper calibration by trained technicians are typically required to resolve these issues.
What to do if your EPB malfunctions
When the electronic parking brake warning appears or the brake won’t engage or release, follow these steps to minimize risk and seek appropriate service.
- Stop safely as soon as you can. Do not force movement if the car won’t roll or if the brake remains engaged.
- Check for obvious warning indicators and try a gentle reset: turn the ignition off, wait briefly, and cycle the ignition back on, then attempt to operate the EPB again if your vehicle allows it.
- Inspect the 12-volt battery and electrical system. A weak or discharged battery can cause EPB faults; if the battery voltage is low, recharge or replace it and re-test.
- Check fuses and relays related to the EPB as described in the owner’s manual; replace any blown fuses with the correct rating.
- Look for a vehicle-specific emergency release procedure in the owner’s manual. If available, use it only as directed and in a safe location; many procedures require accessing a service point near the caliper or interior release mechanisms.
- Consult roadside assistance or a certified technician for diagnosis using proper diagnostic tools (OBD-II codes, EPB module status, and related CAN signals). Do not attempt extensive repairs yourself unless you are trained, as EPB systems are high-torque and can cause injury.
Addressing an EPB fault promptly is important. Delayed diagnosis can lead to the system not holding the vehicle on inclines or failing to release when needed, creating safety risks and potential further damage.
Safety and maintenance considerations
Regular maintenance can reduce the likelihood of EPB faults. Keep the battery healthy, address corrosion on connectors, and follow service advisories from the vehicle manufacturer. If a fault code points to the EPB module or motor, professional repair is usually required to ensure proper calibration and safety.
Summary
Electronic parking brake malfunctions typically arise from electrical supply issues, mechanical binding, or software/sensor faults. Diagnosis usually starts with checking power and fuses, followed by inspection of actuators and calipers, and then assessing control software and sensor inputs. Because EPB systems involve high-torque actuators and safety-critical signaling, professional diagnosis and calibration are advised for any persistent fault.
What does it mean when your car says parking brake malfunction?
A "parking brake malfunction" message usually indicates a problem with the electronic parking brake (EPB) system, often caused by a faulty switch, sensor, motor, or a loose electrical connection. For a traditional parking brake, causes can include a worn or stretched cable, rust, or issues with the rear brake calipers.
This video explains how to troubleshoot electronic parking brake (EPB) issues, including potential causes and a reset procedure: 58sDashboard warning lights YouTube · Jul 9, 2025
Common causes for electronic parking brakes (EPB)
- Faulty switch or sensor: The button or a sensor that tells the system the brake is on or off might be damaged, dirty, or malfunctioning.
- Wiring issues: A loose, corroded, or damaged wire harness or connector, especially near the rear brakes, can trigger a malfunction.
- Stuck caliper or actuator: The motor or mechanism that applies the brake can become stuck or jammed, often due to corrosion or debris.
- System needs a reset: A recent battery replacement or a drained battery can cause system errors, and a reset may be necessary.
- Aftermarket parts: Sometimes, a malfunction can occur after rear brake replacements if sensors or cables are not properly reconnected or calibrated.
Common causes for traditional parking brakes
- Stretched or broken cable: Over time, the cable can become worn, stretched, or frayed, leading to a loss of tension and effectiveness.
- Rust and corrosion: Moisture, road salt, and dirt can cause components like cables, levers, or calipers to seize up.
- Worn brake pads/shoes: The parts that the parking brake activates can wear down over time, making the brake less effective.
- Incorrect adjustment: If the system is not properly adjusted, it may not engage correctly.
- Overheating: Driving with the parking brake partially engaged can cause excessive heat and damage components.
What to do
- Check the basics: Ensure you have completely disengaged the parking brake. For EPBs, check if the switch is dirty or damaged.
- Look for simple fixes: If it's a traditional brake, you can try cycling the lever a few times or gently checking the cables (without forcing them). Some EPB systems can be reset by turning the vehicle off and on again or by using a specific procedure (check your owner's manual).
- Seek professional help: It's not safe to drive with a parking brake malfunction. Take your car to a mechanic to diagnose the problem and perform any necessary repairs, such as recalibrating the EPB system or replacing worn parts.
What are common problems with electric brakes?
Possible Electrical Problems:
- Damaged/exposed wiring.
- Shorted electro-magnet (taking power from whole system causing other drums in the setup not to function)
- Open circuit on electro-magnet (will cause a drum to not brake while the others do)
How much does it cost to fix a parking brake malfunction?
Emergency brake repair costs vary widely depending on the issue, but a common range is $250 to $300 for cable replacement. However, costs can be significantly higher for more complex problems, ranging from a few hundred to a few thousand dollars for things like seized brake components or electronic parking brake system failures. The final price depends on the specific vehicle, the labor rates of the shop, and the parts required, which can include cables, pads, rotors, calipers, or electronic actuators.
Factors influencing cost
- Type of system:
- Cable-actuated: The most common type, with repair costs often averaging around $250 to $300 for a cable replacement.
- Electronic parking brake: Repairs can be more expensive, especially for the actuator, which may cost $150-$200 per side on its own before labor.
- Specific part needed:
- Cables: The most common repair, with a national average estimated around $250-$300.
- Brake pads/shoes: If the parking brake system uses the same components as the main brakes (e.g., integrated drum-in-hat systems), you may need new shoes or pads, which can add to the cost.
- Rotors: If the parking brake is integrated with the rear brake rotors, a seized or damaged rotor will need replacement, adding to the price.
- Actuators: For electronic systems, replacing the actuator is a common and expensive fix.
- Vehicle and labor rates:
- The make, model, and year of the vehicle significantly impact part prices and labor time.
- Shop labor rates vary by location and shop, affecting the final bill.
- Complex issues may require dropping the exhaust or fuel tank, which increases labor time and cost.
Potential price examples
- Average cable replacement: Approximately $250–$300
- More complex repair: A seized rear brake or actuator on a larger vehicle could cost over $1,000 or even several thousand dollars, especially if it causes heat damage to other components.
- Electronic parking brake actuator: Parts alone can range from $150-$200 per side, not including labor.
How do you fix an electronic parking brake malfunction?
To fix an electric parking brake (EPB) problem, try a simple reset by disconnecting the car's battery or using the vehicle's specific reset procedure. If a reset doesn't work, inspect and repair any loose or damaged electrical connections, or consult a mechanic for issues like a faulty actuator, switch, or wiring. For an emergency release, look for an override lever, which can be found in the owner's manual.
Initial troubleshooting and resets
- Perform a system reset: This can fix minor software glitches.
- Disconnect the negative terminal of the car battery for a few minutes, then reconnect it to restart the system.
- Alternatively, follow the vehicle-specific reset procedure in your owner's manual, which often involves pressing the parking brake switch in a specific sequence. A common method is to hold the parking brake switch on, then off, while the car is on and the brake pedal is pressed.
- Check fuses: A blown fuse can cause the EPB to malfunction. Consult your owner's manual to locate and inspect the relevant fuse.
This video demonstrates a common procedure to reset the electronic parking brake: 1mWeeklyToolsYouTube · Jul 6, 2023
Advanced troubleshooting
- Inspect electrical connections: Check all wiring harnesses and connectors for any signs of damage, loose connections, or corrosion and repair them as needed.
- Diagnose faulty components: A persistent issue could be a faulty electronic control unit (ECU), parking brake switch, or actuator. These may require professional diagnosis.
- Bypass a stuck EPB: If you need to move the car immediately, you may be able to manually release the EPB.
- Find the emergency release cable or lever, often located near the rear of the center console or near the left rear taillight.
- Use a screwdriver or pliers to pull the cable until the brake releases. You may need a second person to help release the brake.
When to seek professional help
- If the warning light remains on after trying a reset, it indicates a more significant problem that requires a professional diagnosis.
- Faulty components like the actuator are common but may require specialized tools or expertise to replace.
- For safety, do not drive the vehicle if the parking brake warning light is still on, as it can affect the brake system's lifespan.
