EPB Problem: Passat 3C, 2009 Model

Hello.

I'm on the verge of despair...

Since I replaced the rear brakes on my Passat 3C5, manufactured in 2009, I've been having endless problems with excessively hot brake discs (100°C or more, while the front discs are only lukewarm after the same journey) and increased wear! This problem has existed since the brake replacement (both left and right rear) on both sides.
It might be important to know that I have an EPB (electronic parking brake).

What have I done so far?
- Replacing brake pads.
- Replacing brake discs.
- Replacing brake calipers, including servo motor and mounting brackets.
- Brake fluid changed and the system bled.

In the meantime, all the components have been replaced with original, new VW parts, which were selected based on the vehicle identification number (VIN).

Procedure in VCDS:

- STG 53 - Parking brake -> Basic setting 04.
1. Piston-operated locking motors open.

2. Replaced the linings, pistons, and seals (the pistons in the seals did not need to be reversed because they were new).
3. Brake fluid was changed and the brake system was bled.

- STG 53 - Parking brake -> Basic setting 04.
4. Lock the piston locking motors.
5. Functional test.

Everything worked perfectly.

There are no error codes present in the control unit, neither in the parking brake system nor in the "normal" braking system.

I was able to narrow down the error (using the following steps):

If - STG 53 - parking brake -> basic setting 04.
1. Piston-operated locking motors open.

Then the brakes are definitely not working properly. There's about 0.5mm of clearance between the pads and the rotor.
The behavior is the same when I apply the brakes hydraulically (using the foot brake); in this case, there is also approximately 0.5 mm of air gap with the engine running.

If - STG 53 - parking brake -> basic setting 04.
4. Lock the piston locking motors.

Then the pads are definitely worn down. There's no more space between the pads and the rotor.

If - STG 53 - parking brake -> basic setting 04.
5. Functionality test (open 3 times, close 3 times).

Then the pads are definitely worn down. There's no more space between the pads and the rotor.

Therefore, it is clear that the electronic parking brake is not opening sufficiently.

What can be done about it?

"Thank you very much!"

Raphael.

Hi,

I would almost completely exclude the EPB (Electronic Parking Brake) and its motors, as I understand that the duration for which the motors keep the brakes open cannot be adjusted, and therefore nothing can be changed.

More likely:
- Damaged brake seals, resulting in contaminated or rusted brake pistons, which makes them difficult to move.
- Brake pad guide is too tight due to rust, causing the pads to get stuck in the guide.
- Brake caliper guide is misaligned or seized.

Best regards, Rainer.

Hi Rainer,

As mentioned above, all the parts installed are brand new VW parts, so there's no rust.

But I would appreciate any further ideas.

Best regards, Raphael.

Forgot to replace the master cylinder.

Why should the master cylinder be replaced if the pressure comes from the actuators?

Because I wrote above that the servo motors are probably innocent.
Either the motors start up when the handbrake switch is activated, or they don't.
The basic setting doesn't do anything different; it simply keeps the valve open until the end of its travel is reached, exceeding the motor current.

Furthermore, you mentioned that you had already replaced the servo motors and brake calipers with new parts.

It depends on the servo motors, or rather, their settings.

Therefore, it doesn't make sense to replace other parts unnecessarily.

I was able to narrow down the error (using the following steps):

If - STG 53 - parking brake -> basic setting 04.
1. Piston-operated locking motors open.

Then the brakes are definitely not working properly. There's about 0.5mm of clearance between the pads and the rotor.
The same thing happens when I apply the brakes hydraulically (using the foot brake); in this case, there's also about 0.5mm of air present with the engine running.

If - STG 53 - parking brake -> basic setting 04.
4. Lock the piston locking motors.

Then the pads are definitely worn down. There's no more space between the pads and the rotor.

If - STG 53 - parking brake -> basic setting 04.
5. Functionality test (open 3 times, close 3 times).

Then the pads are definitely worn down. There's no more space between the pads and the rotor.

Therefore, it is clear that the electronic parking brake (actuators) is not opening sufficiently.

There are two different part numbers from ATE for the rear brake pads for the Passat 3C. Both physically fit, but one type squeals.

The topic is old news in the Motor-Talk forum and on the old Passat-Forum.com.

It's possible that you're not experiencing this issue because your pistons are completely retracted, but I still suspect the cause I mentioned earlier. Try searching on Google for "ATE brake pads Passat 3C sticking" or something similar, and I'm sure you'll find plenty of information.

Greetings.
Guste.

The original VW brake calipers, with part numbers 5N0 615 403 and 5N0 615 404, were installed.

Brake pad, original VW (Eco): JZW-698-451-G

I would like to refer you to the following manual:

http://wiki.ross-tech.com/wiki/index.php/VW_Passat_(3C)_Parking_Brake#Basic_Setting

Unfortunately, I am unable to adjust the "Longitudinal Acceleration Sensor (G251)" setting. VCDS always indicates that channel 020 is not available.

How can I adjust this channel 020?

What you can adjust with VCDS, and how to do it, you should best ask your VCDS seller.