UPDATE: I thought I'd check the brake pedal was returning to the top 100%. It was, but the brake lights are working normally now.
And VCDS confirms that the switch is working properly too.
So no idea if the problem was just a glitch or if there is an intermittent fault but it's working for the...
Can anyone tell me if its possible to test the brake pedal sensor using VCDS? I.e reading the value the ECU sees from it, pressing the brake and see if the value changes?
The pushrod that goes from the pedal to the MBC was sitting in the wrong place (right at the top instead of in the middle) and appears to have been scraping against the MBC piston (which has damaged the brand new MBC) instead of pushing the piston in.
I've finally managed to fix my brake problem after nearly 2.5 years and finally have fully working brakes. However, the all of the brake lights are now permanently on.
I've tried all of the following but nothing has stopped the brake lights staying on:
- 3 different brake light switches
-...
The car is now all back together, brake pedal is rock hard and the servo is working perfectly! I'm so happy!
The brake lights are stuck on, even with 2 different brake light switches. Hopefully it's just a fuse though, will check when it's daylight.
Hope this thread helps someone in the...
I believe I've found the issue - the servo pushrod was sitting in the wrong place (right at the top instead of in the middle) and appears to have been scraping against the MBC piston (which has damaged the brand new MBC) instead of pushing the piston in.
That would explain why the pedal never...
Update:
I bench-bled one of my old master cylinders last night and got it to the point where I physically can't compress the piston using both hands - while this isn't as much pressure as using a foot pedal, I'm thinking that one *might* be OK. What's the betting it'll stop working as soon as...
No, but the engine has been off the entire time so the servo shouldn't be affecting anything.
Although if the servo wasn't such a nightmare to change, I'd do it just to be 100% sure.
My 2012 A3 2.0TDI has been off the road for well over 2 years now with a weird brake fault where the brake pedal won't go firm, no matter how many times it's bled or what parts have been replaced.
I've gone to the extreme of blocking off the brake pipes at the ABS pump and bleeding it fully...
I replaced just the brake cylinder, not the servo.
I'm no expert in brake servos, but doesn't it just boost the brake pressure when the engine is on? With the engine off, it shouldn't have any effect, should it?
I would replace it anyway (since nothing else seems to fix the issue), but it...
I've had a thought - my understanding of the master brake cylinder is that it has 2 separate pistons inside - presumably one for the FL & RR brakes, one for the FR & RL brakes...
It's massively unlikely but if all 3 of my master brake cylinders had a faulty seal/piston, could this cause my...
No, the car hasn't moved off my driveway for 19 months and would be dangerous to drive to an MOT. I could pay to get it transported but I don't think it would give me any answers.
Tomorrow, I'm going to take the caliper off and try to see if the piston moves when the pedal is pressed.
I've bled the ABS using VCDS several times.
I've just swapped the caliper for one from a working car and it still doesn't bleed using the 2-man method. I haven't had a chance to try the pressure bleeder yet but I expect the same result.
I removed the bleed valve and the fluid runs out as I'd...
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