Most modern vehicles use the electronic parking brake (EPB), which removes the need for the traditional lever in the cabin. Like the traditional parking brake or handbrake, the electronic parking brake allows you to lock the car’s wheels, preventing it from moving backward or forward unintentionally, especially on slopes.
Although the electric parking brake is a highly-secure technology, it occasionally develops issues. One of the most common issues is a stuck electric parking brake. Since EPBs are more complex than traditional handbrakes, making DIY fixes more difficult.
Thankfully, this article will explain how the electric parking brake works, common electric parking brake problems, and how to resolve the issues.
What is an electric parking brake?
The electric parking brake or emergency brake is a push-button operated device that uses an electrical signal to operate a mechanism that locks the vehicle’s brakes. The electric parking brake offers the advantages of space(since there is no lever)and safety because its technology won’t allow you to drive with the system engaged.
What happens when the electric parking brake fails?
A faulty EPB is not something to take lightly. As explained earlier, the main purpose of the electric parking brake is to stop the car from moving while parked. So if your electric parking brake fails, the Parking Brake Warning Light will remain on even after trying to disengage it. This could mean the cable has jammed and the brake is not releasing properly.
A bad parking brake will also cause issues when parking on slopes and leaving the vehicle without a reliable brake during emergencies.
Furthermore, when the parking brake cable becomes too worn, the parking brake won’t be able to hold the vehicle’s weight. This may cause the vehicle to roll, even when you fully engage the parking brake.
Additionally, if your electric parking brake stops working, it won’t disengage; therefore, the car won’t be able to move. This happens when water and dirt corrode the cables, causing the cables to snap and the brake pads to stick to the wheels.
Can I drive with a parking brake malfunction?
You should never drive with a faulty parking brake. Otherwise, it can cause serious damage to your transmission and even cause an accident. Although you don’t use the parking brakes while driving, they come in handy in certain situations.
For instance, the parking brake helps with emergency braking and will prevent the vehicle from skidding. Also, you can engage the parking brake when driving uphill, allowing the driver to hold the accelerator and clutch pedals steady without the vehicle rolling backward.
You can also use the parking brake if the main brakes fail while driving. In this case, you can engage the parking brake lever and slowly reduce the speed to a stop. Therefore, driving with bad parking brakes puts you at risk of an accident as you have no system to stop the vehicle when the main brakes fail.
The parking brakes also ensure your vehicle is secure in case another vehicle rams into yours from behind. So if this happens while driving with a parking brake malfunction, your vehicle will roll backward instead of jolting forward.
It’s important to avoid driving your vehicle if your EPB doesn’t disengage. However, doing so can wear out or damage other components of the parking brake system.
What do I do if my electric parking brake is stuck?
The best way to fix a stuck electric parking brake is by first identifying the cause of the issue. There are several reasons that can cause an electric parking brake to stick. The following are the most common reasons and how to troubleshoot them.
Corrosion or rust
If you hardly use the EPD in your vehicle, moisture can build up on the mechanical parts of your EPD system and cause corrosion over time. This causes the cable that engages the parking brake to get stuck. This problem is also common in vehicles in the northern climates, where they apply road salt regularly.
Depending on the rust’s severity, it can be difficult to fix this issue yourself. However, if the rust is mild, you can dislodge the parking by doing the following:
- Apply and release the brake several times.
- Then, shift into drive and reverse several times to move the vehicle back and forth to break off some rust.
Freezing weather
It’s common for the EPB to freeze and become stuck in extremely cold weather. To fix this issue:
- Turn on your vehicle and allow the engine to run for about 30 minutes. The heat from the engine will warm the ice on the parking brake and melt the ice.
- Rev the engine gently to heat the engine much faster. This, in turn, will speed up the ice-melting process.
- Try disengaging the parking brake several times after the car has warmed up to break up any remaining ice.
- If your parking brake fails to engage, there may be more complicated problems, such as ice in your cable housing.
Overapplied electric parking brake
If you pressed the parking brake button too hard, you might have accidentally jammed it. Likewise, excessive force when applying your parking brake can stretch the cable or cause the brake shoe or rear brake caliper to stick against the wheel’s drum walls, preventing them from disengaging correctly from the wheels.
Try applying the brake pedal repeatedly to release the stuck parking brake. If that doesn’t work, get help from a professional mechanic.
You should use only moderate for when applying the parking brake to avoid this issue in the future.
Engaging the parking brake for too long
Ideally, you should only leave your parking brake engaged overnight. However, leaving your parking brake on for too long can become stuck in place. This could be due to freezing from low temperatures or corrosion.
If this happens, try applying the same solution to fixing a frozen parking brake. But if you won’t be using your car any time soon, avoid engaging the parking brake and then use a pair of wheel chocks to keep your vehicle in place. Also, ensure to park your vehicle in a place with controlled temperatures to prevent freezing.
How to release the electronic parking brake
Here’s how to release the electronic parking brake system:
- Switch the ignition.
- Then with the brake pedal pressed down, push down on the EPB brake switch on the console.
The EPB will also release automatically with the ignition switch on, the transmission in gear, and the driver pressing the accelerator pedal. Since the EPB is electronic, an electronic system failure will cause the electric parking brake to stop working and not release.
So, if none of the above solutions work to release the stuck EPB, you can manually release the stuck electric parking brake. But the procedure varies depending on the type of EPB in your vehicle.
This process works on the caliper integrated system. Releasing the stuck brake will require removing the wheels and EPB motor and unwinding the brake caliper.
- First, ensure the vehicle is on solid ground, and there are no cars around you.
- Raise your vehicle using a floor jack or jack stand.
- Get under the vehicle and find the rear brake caliper. Then observe how the parking brake motor is mounted. This is because some are serviceable, while others aren’t.
- It will have bolts securing it onto the aluminum caliper housing if it is serviceable.
- Remove the bolts holding the electric motor to the caliper housing.
- Then carefully remove the parking brake motor without unplugging it and secure it out of the way. Disconnecting the motor from power could cause the system to lose its basic settings. Other times it may require you to replace the brake caliper and the electromechanical parking brake motor to get the system running correctly.
- Ensure the motor or harness does not contact any of the suspension parts.
- Release the brake caliper. Take a socket that fits in the back of the caliper piston and turn the caliper piston adjustment bolt half to one full turn on both sides.
- Carefully lower your vehicle, ensuring the parking brake motors are not caught on any suspension components.
- After fixing the issue, reverse the procedure on the parking brakes. The control module on most newer systems will relearn the air gap between the brake pads and rotors by running the electronic parking brake several times. But sometimes, you’ll have to perform a function test using a scan tool to relearn the air gap.
Do electronic parking brakes automatically disengage?
On the newer systems, the electronic parking brakes release automatically as soon as you drive off. To manually disengage the electronic parking brake:
- Switch on the ignition
- Press the brake pedal
- Then press the electric parking brake switch. When you release the parking brake, the parking brake warning light turns off.
For the other systems, you must press the brake pedal and flick the parking brake switch again to disengage it.
Your electronic parking brake will automatically disengage under the following circumstances:
- The accelerator pedal is depressed
- The driver’s door is closed
- The parking brake system is in working condition
The parking brake warning light will go off to indicate that you have released the electric parking brake. If the parking brake warning light stays on, the electric parking brake will not automatically release. Instead, you will have to release the EPB manually using the switch or button.
How does the electronic parking brake work?
The traditional handbrake uses a lever that tightens a cable or series of cables connected to the car’s rear brake pads or shoes on the drum brake or disc brake to lock the car securely. The electric parking brake works on the same principle to achieve the same effect but forgoes the mechanical lever and hydraulics braking system.
Rather, the EPB is an electrically controlled handbrake and works with the electric control unit (ECU) and actuator mechanism.
The electronic parking brake system consists of the following:
- Electric switch in the cabin
- Control module
- Two rear electric motors or one electric motor and cables
- Brake position sensor
There are two variations of the EPB systems which function slightly differently:
Caliper integrated systems
This is a full electric parking brake. This mechanism exerts more brake force but is more challenging to control.
So, when you press or pull the parking brake button or switch near the center console, it sends an on or off signal to the electric parking brake module or controller. The module processes the command and sends a ground and power supply to the two ECU-controlled electric motors (actuators) on each rear caliper.
Then each motor turns a spindle screw which pushes the pistons and brake pads against the rotor. The parking brake remains engaged until commanded off.
This is on models such as Volkswagen Passat, Audi A6, A8, and Mercedes-Benz.
Cable puller systems
This is a hybrid technology between a fully electronic parking brake and a traditional one.
Activating the EPB button sends a signal to the electric parking brake module, which powers the single electric motor. The electric motor pulls two cables attached to the rear caliper parking brake levers, and the piston and pads tighten against the rotors to hold the wheels in place until the driver sends a release command.
You will find this EPB type on models such as Lincoln LS, Jaguar X-Type, XJ, and most Land Rover models.
Whatever system your vehicle uses, the principles remain the same－pressing the EPB button locks and unlocks the wheels.
Note: If you engage the parking brake switch while driving the vehicle at a speed greater than 6mph, the control unit will send a brake-apply request to the ABS control unit, and the hydraulic brakes will engage. Once the vehicle stops, the hydraulic brakes will release, and the EPB will apply to hold the vehicle.
Signs that your electronic parking brake is faulty
The electronic parking brake is an essential safety feature in your vehicle. Fortunately, there are several ways to know that your vehicle’s EPB is failing or faulty.
- Flashing or solid parking brake warning light. This could signify other issues, but you should service your vehicle to rule out a faulty electronic parking brake.
- A message on the dashboard will appear. The message alerts you that your vehicle needs parking brake service immediately.
- The electronic parking brake doesn’t engage when it should, especially on a hill. If the parking brake system is stuck, the car won’t move or will drive while the brake is still engaged. If the EPB is on while in motion, it will cause your brakes to overheat and cause other issues. You will notice the parking brake light is on, and driving and accelerating will be difficult.
- You’ll notice it becomes more difficult to stop. This is because driving with a stuck EPB can wear down the brake pads quickly. So you could find you’re taking longer to come to a complete stop which could be dangerous during emergencies.
- A burning smell is also an indicator of a stuck EPB. That is the smell of your brakes getting worn down because the parking brake is engaged while you drive.
The electronic parking brake is not working.
There are several reasons why your vehicle’s EPB stops working. The repair also depends on the issue. Here are the most common reasons why your EPB is not working:
Faulty parking brake switch or button
A faulty or dirty parking brake switch or button is a common issue. The button or switch is usually in the center console, which is prone to dirt. There is also the risk of drink and food crumbs spillage on the button, lint, dust, and other debris that can go inside it and cause it to malfunction.
First, you can try cleaning the button. If it doesn’t work, you’ll need to replace it with a new one.
Faulty wiring
The wiring in your electronic parking brake system could be loose, worn out, or shorted. So first, check the entire wiring and the clips connecting the components.
You can easily reconnect loose connections. But you will have to replace the wires if worn or shorted, as they no longer pass the current needed to send commands between components.
Faulty electric parking brake motor
The EPB system has motors on the rotors responsible for locking the wheels when you activate the parking brake. If the motor or motors go bad, then the wheels will never lock correctly. If the electric motor is faulty, it will need a replacement.
Electronic parking brake not releasing
There are several reasons why your EPB is failing to release. Unfortunately, the diagnosis procedure is complicated and requires a scan tool and a professional mechanic. The troubleshooting procedure also depends on which component has failed.
Below is a list of all the problems that could prevent your EPB from releasing.
- Blown fuse
- Faulty EPB motor
- Faulty EPB wiring
- Faulty EPB switch
- Faulty EPB sensor
- Faulty EPB controller
Start by pressing the EPB button; if you hear the motor or motors running, it’s likely a failed motor. If there is no motor noise, it’s likely an issue with the switch or controller. Therefore, you will need to release both rear wheels manually.
Electronic parking brake not holding car stationary
Over time or through a lack of normal use, your EPB may stop holding your car as it should. There are several reasons that could explain this.
Check this too: How to Deep Clean and Restore Your Car’s Dashboard
Faulty adjuster wheel
Usually, you use an adjuster wheel to adjust your brake pads manually and change the shoes’ spread inside the drum. But if the adjuster wheel is damaged or stuck, you will not be able to adjust the shoes. Therefore the parking brake won’t hold the wheel.
Worn out drum
If you haven’t resurfaced your drums in a while, the wear on the inside may prevent the shoes from making contact with the surface. Therefore, the wheels won’t stay in place when you use the parking brake. You will need a professional mechanic to replace the drum for you.
Corrosion
Rust can accumulate on various parts of the EPB system, preventing the parking brake from holding the car. Therefore, the mechanic should inspect the entire parking brake, including the cables, return springs, and shoes, to identify the faulty part.
Low voltage
The EPB relies on the necessary amount of power to function correctly to stop the vehicle when necessary. Therefore, the parking brake won’t hold the wheels if the motor receives less or more voltage than necessary due to an issue with the battery or ECU.
Conclusion
Several things could go wrong with your vehicle’s electric parking brake. Unfortunately, there are few situations where you can solve the issue yourself. So your best bet is to get a professional to diagnose and repair the issue. The best way to avoid EPB issues is by maintaining the system with regular service and frequent use of your parking brake. It will prevent corrosion and alert you on issues before they get out of hand.