On a car with an electronic parking brake (EPB), the rear calliper has a small motor that pushes the piston. If you try to wind the piston back by force with a tool, as you would on a conventional calliper, you can damage that motor or its mechanism. The right way is to put the system into maintenance mode with a diagnostic tool so that it retracts the callipers itself.
How EPB maintenance mode works
The EPB function on a diagnostic tool tells the parking brake control unit to open the callipers fully. With them open, you can change the pads (and discs if they are due) without forcing anything. When you have finished, the tool closes them again, sets the position for the new pad thickness and, on some cars, runs a calibration or logs the change.
While the system is in maintenance mode, the parking brake does not work. That is why the order of the steps matters.
Safety: work on level ground, with chocks on the front wheels and the gearbox in P or first gear. With the EPB open, the car has no parking brake. Use proper axle stands and never get under a car held up only by a jack.
Step by step: changing the rear pads
- Get the car ready. Level ground, chocks on the front wheels, gearbox in P or first and engine off.
- Connect the tool to the OBD2 port and turn the ignition on without starting the engine.
- Identify the vehicle by VIN or by selecting make, model, year and engine.
- Go into Service → EPB (it may be listed as parking brake or pad reset).
- Choose the option to open or retract the callipers (maintenance mode or pad change) and wait until you hear the motors run and see the confirmation message.
- Switch the ignition off if the tool tells you to, raise the car and take off the rear wheels.
- Change the pads. Clean the calliper and carriers, check the condition of the disc and fit the new pads. If the piston needs to go back a little further, check the manufacturer's manual: on some callipers it is wound back and on others pushed, always with the motor already retracted.
- Refit the wheels, lower the car and reconnect the tool with the ignition on.
- Choose the option to close the callipers (exit maintenance mode). If your car asks for the pad thickness or a calibration, follow the on-screen instructions.
- Check it works: apply and release the parking brake several times with the switch and make sure no warning lights stay on. Read the faults in the EPB module and clear any left over from the procedure.
New pads need bedding in. The first few stops will be less effective: test the car at low speed somewhere safe before heading out on the road.
Common mistakes
- Disconnecting the battery to "reset" the EPB. It does not retract the callipers and can leave the system with fault codes.
- Pressing the parking brake switch with the calliper off. The motor pushes the piston out of its bore.
- Forgetting to exit maintenance mode. The car will be left with no parking brake and the warning light on.
- Selecting the wrong model on the tool. Some manufacturers use different systems depending on the year or calliper type.
Which iCarsoft tools can release the electronic parking brake
The EPB / pad reset function is on the current multi-brand tools and on the V2.0 single-brand tools with an official iCarsoft spec sheet. The V1.0 range does not have it: its service functions are limited to oil and steering angle.
| Tool | Type | EPB | Bidirectional |
|---|---|---|---|
| CR Pro | Multi-brand, 58 makes | Yes | No |
| CR Pro+ | Multi-brand | Yes | Yes |
| CR Max P | Multi-brand, 58 makes | Yes | Yes |
| BMM V2.0, VAWS V2.0, MB V2.0… | Single-brand | Yes | No |
| V1.0 range | Single-brand | No | No |
For a driver who changes their own pads, the CR Pro or a V2.0 for their make is enough. If you also want to activate components for diagnosis (ABS pump, fans, actuators), you need a bidirectional tool such as the CR Pro+; we compare them in CR Pro vs CR Pro+. You will find every tool for home use under diagnostic tools for DIY drivers.
When the rear pads are due
Many cars have a wear indicator light that comes on when the pads reach their limit, but not all of them have one on the rear axle. Check them at the same time as the fronts, looking at the thickness of the friction material through the wheel or with the wheel off. If you hear a metallic squeal when braking or feel vibration, don't ignore it: the pad backing plate may already be rubbing on the disc.
If the parking brake does not apply after closing the callipers, or an EPB fault appears, don't force the system by pressing the switch over and over. Read the code, check the connector on each motor and repeat the closing procedure with the tool.
After the pad change
If you are also changing the brake fluid on the same job, on cars with ABS it is best to bleed it using the tool's dedicated function. And if the dash says a service is due, take the chance to do the service reset when the time comes.
