2007 Passat EPB motor repair

[r1chm]

Evening All

Been having a read through some of the EPB repair threads on this site and just wanted to clarify some points if I may.

I recently had the EPG issue where the brake seized on unexpectedly after i'd applied it, gave me the "Parking Brake Fault - See Owners Manual" message and beeped at me. At the time, I had not read about this seemingly common issue. It also happened in the middle of Leeds city centre during rush hour, so my frantic trying to go, press parking brake button, rinse & repeat in desperation probably didn't help matters given what I have read about the control module :/

It seemed like the driver side was stuck on, but passenger side was operating normally. Eventually, the drivers side released and I was on my way. I had the permanent orange P warning light, together with a flashing red parking brake warning light and the EPB button was flashing, as appears to be quite common. Also had the constant Beep whilst driving. I could put up with this and just didn't use the hand brake anymore.

Now comes MOT time, I decided I best take a look. As expected from what I had read, the bottom of the motor housing had cracked on drivers side and allowed moisture in which knackered things up. I got a new EPB motor from eBay - I know it will just be a cheap copy but it had good reviews from previous buyers, and this car only needs to last me a couple of years or so, so I bought it.

Whilst I had the EPB motor off, I thought I had best check to make sure the piston wasn't seized. The 6-Torx fitting that the motor spline slots into moved freely, and I was able to wind the piston out no problem, smooth as you like. When I tried to wind it back in again, the piston didn't actually move back with the winding. I expected it to wind itself all the way in too? but it stayed exactly where it was. I had to push the piston back in manually (after I had finished manually winding the piston torx thing back all the way). I achieved this by undoing the bleed screw and it went back in all the way smoothly enough. I don't know if this is normal behaviour?

Anyway, after I finished cleaning up the (aluminium?) thing that the O-Ring slots onto, I fixed the new motor in place, put the caliper back on, cleaned brake discs, bled brake, put wheel back on and eagerly sat in the car & started it. I fully expected peaceful nothingness. Unfortunately my night was ruined by the same flashing lights as before. I decided maybe I needed to give it a quick run out and use the EPB a few times so that the car knows its fixed. Queue annoying beeping.

Nothing I tried resolved my issue so I dejectedly went for a cup of tea and a moan to the missus about how **** EPBs are, then i remembered I forgot to plug the EPB in after i'd finished. I practically skipped outside, face under the car with a torch and sure enough the EPB motor was unplugged. Hurrah! full of anticipation i plugged it in and went to grab my keys. For the second time in about 20 minutes my night was ruined as the same fault/issues remained. I disconnected the battery for half an hour to see if that would clear any faults but it did not.

Now, reading through this site I notice people mentioning putting the car into service mode but I obviously didn't do this, and I don't have the tool to do it. Have I broken it? I can hear BOTH motors working, but only the passenger side engages. Even though i hear the drivers motor "work" it does not engage the hand brake at all.

Is it just a case of taking it to a VW specialist and have them retrospectively tell the car the brakes have been changed using their magic VCDS(?) machine? I only have access to the Torque Pro app using my phone. That doesn't show any fault codes when I search, but at this stage I am not even sure that this app can do anything other than report the engine RPM

If anyone can shed any light on this i'd be eternally grateful, and for confirmation of whether the caliper behaviour described above is normal or indicates a nackered caliper?

Thanks all
Rich

[Crasher]

VCDS warns you about messing around with this system, you can fry the controller just by looking at it the wrong way...

[philipharmes]

If both EPB motors are working I think your controller will be fine.
But you do have to be carefull not to keep pressing the button repeatedly.

Every use heats up the FET output semiconductors & they will overheat & be destroyed by continual operation.
So best to leave about 30 seconds between each application.

The behaviour of the piston when you wound out the EPB screw is normal.
The screw just moves a plate behind the piston but is not directly attached to the piston.

So it will push the piston out but won't pull it back in.
You have to wind the screw which withdraws the plate behind the piston, then push the piston manually back in.

When you removed the EPB motor the controller remembered that the brake was on.
So before you refit the EPB motor, you need to wind the screw pushing the piston out until the pads clamp the disc.

But as you have operated the EPB a number of times now, it probably doesn't know where it is now.

Basically whatever state the working one is in ie. is the brake on or off, then that needs replicating on the side you have had apart.
So get the good one to be on, then wind the repaired one until the pads clamp the disc.

Work the button a couple of times allowing cool down time between presses & it should be ok.

Another problem that can occure is that the female spline on the caliper that mates with the EPB motor rusts away.
The spline then eventually rounds off & doesn't engage with the spline on the EPB motor, allowing the motor to turn, but not turn the caliper screw.
This may well have happened in your case as you can hear the motors turn.

You can get a replacement caliper screw off eBay, but does of course need the caliper stripped down to replace it.

Be aware there are two different sizes of spline.

[r1chm]

Thanks for your input guys.

I will try manually clamp the disc this weekend and see what happens. Up to press its been good side handbrake off, and repaired side wound back all the way but I guess the good side probably doesn't actually wind back all the way when I disengage the HB? It just winds back enough to release the pads?

When you say 2 sized splines, do you mean the male 12 and 6 sided torx? I made sure I bought a 6-sided as thats what came off.

I don't believe the female spline has rusted away - as I can wind it in/out manually no problem using a torx driver. Glad to hear it doesn't sound like the actual caliper is nackered.

Rich

[philipharmes]

" When you say 2 sized splines, do you mean the male 12 and 6 sided torx? I made sure I bought a 6-sided as thats what came off. "

It's a few years since I repaired my wifes Passat, just remembered there were two different types, changed around 2008 I think.

When the handbrake motor winds it only moves about 1 turn to wind the pads on/ off.

When the pads clamp tight the HB motor is stalled, so draws a lot more current, the HB controller senses this so stops the process & then knows the HB is on.

[DieselMonster]

You need to tell us what the fault codes are. You need to carry out a resync of epbs using the VCDS. You may need a new control module and that would need coding in with vcds. Additionally it may need a new epb button too. It can be an easy fix of swapping out the motors but sometimes it needs vcds.

[r1chm]

Hi All

Quick update on this.

I ended up buying a new/reconditioned caliper with motor from a German car part specialist because I wasn't happy using the existing caliper just with a new motor, since it was covered in crap from the previous failed seal.

I borrowed a SP Diagnostics VAG service tool (SP Diagnostics Audi VW Electronic Park Brake (EPB) Tool - YouTube one of these... not my video BTW). I did the "open" sequence, old caliper off, new caliper on, bled the system, plugged in the EPB motor and then did the "close" sequence. During both the open and close sequences I can hear BOTH motors in action, yet the hand brake on drivers side never actually engages. I performed the open/close sequences a few times and its the same result.

I have a generic error code reader, which is showing no error codes. I have also bought and tried a new EPB switch with no luck.

I don't have access to a VCDS system so if that is required I may well now be at the mercy of the local dealer... unless I'm doing something obviously wrong and someone can point me in the right direction? Or if anyone local to the Selby, North Yorkshire or Leeds, West Yorkshire areas has a VCDS system and fancies scanning/trying to reset it for me for some beer money?

Any help much appreciated.

Thanks

[DieselMonster]

Have you replaced the button and if the drivers side is not working, any fault code, is parking brake button flashing? I can come down and have a look but answer the above questions first. I did everything you did, then I changed the parking brake button and had to recode a used parking brake module as mine was fried. Then I did the brake sequence and then it worked.

[r1chm]

Ta for coming back to me.

I bought a new button and it does exactly the same as the old button.

The current symptoms are a permanent orange brake warning light on the dash, together with a constant red flashing warning light and the EPB button warning light flashing. When driving there is a constant audible beep. Only passenger side of the hand brake is engaging, even though i can hear both motors working.

Someone earlier in the thread said the parking module could be fried but i am hoping that is not the case, given both motors are being manipulated by the SP Diagnostics tool?

Someone else mentioned that the 2 EPB motors might be out of sync so requires VCDS to resync the control module.

I'm open to suggests at this point... MOT due next month :P

Rich

[DieselMonster]

Yes, the control module becomes damaged when you use it with only one motor working. The earlier revisions of the module were very sensitive. If you've changed the motors, button with an OEM one and wiring is most likely fine, chances are it's your control module.

What you need to do is find out what control module you have, either by looking through VCDS or removing the centre console where it is located. Then get another control module with the same revision number as newer may not work well and code it in with VCDS. To code it is a lengthy process as you have to set the steering angle sensor, brake pedal and code in the ABS module as you'll lose the coding once you change the parking brake module. It sounds tougher than it is.

What you need to do now is find out what model number of the parking brake module is. Then buy a used one as I did for about £25 and code it in or a brand new one, up to you. Then I cleared all the codes, went into basic settings in VCDS and I did a function test which opens and closes the brakes so both motors know how much torque to apply to open and close the brakes.