How to Change Rear Brakes With an Electronic Parking Brake

Rear disc brakes with an electronic parking brake (EPB) don't wind back like standard calipers. You have to retract the caliper’s actuator motor into service mode before the brake pads or rotor will come off. Prying the piston back manually will destroy the motor. The correct way to do this is by hooking up a bidirectional OBD2 scan tool to electronically open the module. If you don't have a scanner, the field workaround is to unbolt the actuator motor and manually turn the internal spindle clockwise. Once that motor is backed off, you can swap the pads and rotors normally.

What is an Electronic Parking Brake (EPB) rear caliper?

On modern cars, the parking brake isn't a cable you pull. It’s an electric actuator motor bolted right to the rear caliper. When you hit the button in the cabin, that motor turns an internal spindle that winds the piston out to lock the wheels.

If you treat this like an old-school front caliper and just shove a C-clamp in there to pry the piston back, you will snap the motor's internal gearing. A replacement EPB actuator will run you $200 to $400 for the part alone, plus the headache of fixing a car stuck in limp mode.

Comparing EPB Retraction Methods

How do you put an electronic parking brake in service mode with a scan tool?

You connect a bidirectional scan tool to your OBD2 port, pull up the electronic parking brake menu, and hit "Maintenance Mode" to electronically wind the piston back. This is the exact procedure the manufacturer designed.

The Procedure

1. Chock the front wheels and put the car in park.
2. Hook up your bidirectional scan tool, select your make and model, and navigate to the parking brake actuator or EPB menu.
3. Select Open, Retract, or Service Mode. You will hear the motors whining as they wind back.
4. Pull the caliper bracket, pads, and rotor just like a normal brake job. Never pry on the piston.
5. Bolt on the new parts, torque the hardware, and use the scanner to run Close or Apply to seat the piston.
6. Cycle the parking brake from the driver's seat, take it for a low-speed test stop, and make sure the dash is clear of warning lights.

How do you retract an electronic parking brake without a scan tool?

If you are stuck in the driveway without a bidirectional scanner, you can pull the actuator motor off the back of the caliper and manually turn the internal spindle clockwise to retract the piston.

1. Unplug the wiring harness connected to the EPB actuator motor.
2. Pull the two fasteners (usually Torx or Allen) holding the motor to the caliper housing.
3. Pull the motor straight off. The exposed gear underneath is your piston adjuster (spindle).
4. Turn the spindle clockwise to wind the piston back into the bore. If it starts walking out, stop and turn it the other way (some left/right sides are reverse-threaded).
5. Swap your pads and rotor, then bolt the motor back on and plug it in.
6. Cycle the parking brake a few times to get the pedal firm and check the hold on a slight incline.

Note: This gets the job done, but it won’t clear a dashboard EPB fault code if you already triggered one.

What is the best budget scan tool for EPB service?

A Bluetooth TOPDON bidirectional scanner has enough juice to run EPB service modes for most driveway brake jobs. If you wrench every weekend, step up to a handheld TOPDON AD600S.

(Disclosure: We earn a small commission on these Amazon links at no extra cost to you.)

Budget Pick: Buy the budget TOPDON bidirectional EPB scan tool on Amazon. It comes with a year of free updates. After that, renewing the Lite software costs around $49 a year if you want to keep the bidirectional EPB features active.

Mid-Tier Pick: Buy the TOPDON AD600S OBD2 scanner on Amazon. This gives you better coverage and a dedicated handheld unit so you aren't relying on your phone with greasy hands.

What if the rear brakes have drums instead of EPB discs?

Look behind the wheel hub. If you see a big round drum instead of a caliper with a motor bolted to it, stop right here. You have drum brakes, which means dealing with springs, shoes, and wheel cylinders. Read how rear drum brakes work before tearing into it.

FAQ

Can I change EPB rear pads without a scan tool?

Yes, by unbolting the actuator motor and manually turning the spindle clockwise. However, this is a field workaround; using a scan tool to command service mode is the proper method.

Which way do I turn the EPB spindle?

Turn it clockwise to retract the piston on most cars. If the piston pushes outward, reverse your direction, as some calipers use opposite threads.

What scan tool works for electronic parking brakes?

You need a bidirectional scanner, not a basic $30 parts-store code reader. A budget TOPDON Bluetooth kit or a handheld TOPDON AD600S will do the job.

Will a cheap code reader retract the EPB?

No. Cheap readers only pull fault codes. They cannot send commands to the vehicle's computer to open the parking brake motor.

What should I do if the rear brakes won't spread?

If your caliper is stuck or the dash lit up with an EPB warning, text a photo to (770) 686-7955. Road Wrencher will bring a bidirectional scanner out to your driveway, command service mode, and quote a flat labor fee to get you back on the road.