Right now I am doing a the rear brake replacement(first time) with Vag-Com. I opened the piston but it didnt open enough to fit over the new pads. I went back in Vag-Com to try and cycle the piston. It closes but it will not open back up. I get error codes for parking brake and it will not open up. I cleared the codes but nothing happens. Also nothing was disconnected.

Car is on jack stand as I type and I have not a clue what to do next.

 

Any chance it internally opened but physically did not? Try separating with slight pressure.

 

Now I have a bigger problem. The piston opened so much that it popped off!! Uggg!! What to do now???

Mister Bally I tried alittle pressure but not too much cause I thought I might break something.

 

If it actually "opened" I don't see how it could "pop off." Maybe you mean just the rubber dust boot surrounding the piston? If so, just work it back on by hand. If instead it "closed" so that it basically came all the way unscrewed and the piston came out, that I don't know other than common sense trying to get it back together and reengaged.

 

When it says it is open, you still have to push the piston back with a piston depresser tool.

 

Yes. First you open handbrake with VCDS than push the piston in. If you do not have special tool (most likely) a carpenter clamp can do the trick. Just set it across one used pad and the back of caliper and squeeze it back. If that rubber protector popped out just push it back in place. That's a bit pain but that's what it is. I hope you didn't pop out the piston and spilled the oil (brake fluid). In the case you did you have to push it back and get rid of ear from the braking system. I really hope that's not the case.

Don't forget to measure new pad thickness.

 

Thanks for the help everyone. MP4, I worked the piston back in there and got the motors to go back in forth with no problems. I changed the rear pads(added new pad thickness threw adapation in VCDS) on both sides and bleed the brake lines. Now I am getting error codes. I tried resetting but I get nothing. The motors both work and I verified that both making them move. Am I missing something?

Saturday,16,July,2011,17:48:16:57746
VCDS Version: Release 10.6.4 (x64)

Address 53: Parking Brake Labels: 4E0-910-801.lbl
Control Module Part Number: 4E0 910 801 C HW: 4E0 907 801 A
Component and/or Version: EPB A32C0220 H02 0220
Software Coding: 0000532
Work Shop Code: WSC 08201 444 74977
VCID: 1F471ADBB72D
Fault Codes have been Erased

4 Faults Found:
02433 - Supply Voltage for Right Parking Brake Motor (V283)
012 - Electrical Fault in Circuit - MIL ON
Freeze Frame:
Fault Status: 11101100
Fault Priority: 1
Fault Frequency: 1
Reset counter: 213
Mileage: 176232 km
Time Indication: 0
Date: 2011.07.16
Time: 17:38:41

Freeze Frame:
Voltage: 11.59 V
Count: 87

02596 - Rear Brake Pads Worn
002 - Lower Limit Exceeded
Freeze Frame:
Fault Status: 01100010
Fault Priority: 6
Fault Frequency: 1
Reset counter: 213
Mileage: 176232 km
Time Indication: 0
Date: 2011.07.16
Time: 17:44:13

Freeze Frame:
Voltage: 12.53 V
Count: 60

02596 - Rear Brake Pads Worn
008 - Implausible Signal
Freeze Frame:
Fault Status: 01111000
Fault Priority: 6
Fault Frequency: 1
Reset counter: 188
Time Indication: 0

Freeze Frame:
Voltage: 9.94 V
Count: 61

02432 - Supply Voltage for Left Parking Brake Motor (V282)
012 - Electrical Fault in Circuit - MIL ON
Freeze Frame:
Fault Status: 11101100
Fault Priority: 1
Fault Frequency: 1
Reset counter: 213
Mileage: 176232 km
Time Indication: 0
Date: 2011.07.16
Time: 17:38:41

Freeze Frame:
Voltage: 11.49 V
Count: 86

 

as long as it is mechanically and hydraulically sound, and the parking brake functions. Notice how high your fault count is on a couple of the errors, plus the low voltage on one. The high count (many dozens) suggests these are old (pre pad change) faults. Thus, I would button it up first, plus clear all the brake codes. Then make sure your pad thickness wear change stuck. That low voltage/implausible stuff says maybe time to get the battery juice back up before reaching any conclusions.

FWIW, last I looked I had one of those rear codes too I couldn't track down after a pad change and VAG COM reset and calibration, even though it all functions. The pad wear adaptation didn't stick the first time though, so after being sure the car had new miles on it I was going to check it on my next scan again.

 

Thanks for the help everyone. I buttoned everything back up. I just got really nervous when the piston popped off and I thought brake motor had broke. After working the piston back, I got the pads back on and bleed the brake fluid. After unsuccesfully trying to clear codes. I just drove the car to do a few errands and after I got back home(a hour later), the rear brakes started it's auto calibrate and the codes end up clearing afterwards without using vag.

I was pretty nervous and thought I just caused myself a pretty hefty repair bill.