Brake Knock And Warning Light

[skinner2k3 3]

Hi

 

Seeing as the Passat forum is cack compared to this one I though I would get peoples opinions on here.

 

At the weekend I applied the brakes and felt a mechanical knock come up through the pedal, I am sure I heard it too. The brakes didnt feel right. The ESP (Elec Stability Prog) light flashed and then stayed on. This light will also come on if the ABS is at fault. In the past I have had the light come on (but no knock) when carrying passengers in the back of the car, but will go out and not return when the ignition is switched off/on. Two garages have put this down to a load sensor in the rear being faulty.

 

It felt like perhaps a pad had broken up or was moving in the carrier. In fact it felt more like 205 1.6 GTI brakes when the sliders are worn and there is movment in the carrier. But I got the wheels off and the pads are fine, nothing seems to be loose.

 

I did wonder if a bush has gone somewhere and I felt movement in a suspension component but it has just gone through an MOT so I would think they would find that.

 

Not sure where to look next, dont want a VW mechanic crawling over it for 3 hours at £80/hr only to tell me nothing is wrong.

 

The car is a 2002 VW Passat TDI Sport.

 

Any ideas?

[Tom Fenton 1,542]

Sounds to me more like the ABS pump or something playing up rather than a mechanical problem. When the ABS does something you do feel it through your foot on the pedal, and also it makes a noise.

 

If the light is on the first thing to do is get it plugged in and see what its trying to tell you.

[smithy 1]

Common problem on some vag abs pumps a pressure switch inside gives trouble,used to be a new pump job but vag finally admitted a fault and released a repair kit for couple hundred pound.

Although you will need to get fault codes read first do a google for vw abs,ESP probs loads info will come up.

[smithy 1]

Get yourself a cheap vag com off fleabay for about a tenner save a fortune on diag tests

[skinner2k3 3]

Oh god, sounds expensive! It has been on VAG com a couple of times during the period that I have had the flashing light occasionally and nothing flagged up.

 

I do actually have a copy of VAG COM and the lead at home, but never wanted to use it for fear of screwing something up.

 

A local VW specialist is looking at it tomorrow. I explained the problem and he said it's quite common for the pads to jam in the carriers, what I may have experienced was it freeing up as I applied the brakes causeing the knock I felt.

 

I will ask them about the ABS whilst it is in.

 

This sounds either fairly simple or chuffing expensive, lets hope its the former!

[Tom Fenton 1,542]

If the light on the dash is on, then I think you are kidding yourself that it is just something simple like a sticky pad I'm sorry to say.

 

Before you take it to this place and start paying labour at £40 per hour or whatever, I really would get it plugged in yourself and see what it can tell you. The free VAGCOM stuff won't do enough to let you change anything, so all it will do is read codes.

 

I have a VAG plug in scanner, if you were closer I'd offer to plug it in for you.

[skinner2k3 3]

If the light on the dash is on, then I think you are kidding yourself that it is just something simple like a sticky pad I'm sorry to say.

 

Before you take it to this place and start paying labour at £40 per hour or whatever, I really would get it plugged in yourself and see what it can tell you. The free VAGCOM stuff won't do enough to let you change anything, so all it will do is read codes.

 

I have a VAG plug in scanner, if you were closer I'd offer to plug it in for you.

 

Your probably right. Although the light went off the next time I switched the ignition off and didnt return on the way home.

 

Normally I would have a look myself but I need the car to go on holiday this weekened and wont have time before then to tinker.

 

Its over there to be looked at today, they are going to check over the brakes physically and have it plugged in whilst they do it. I think they are more than £40/hr so I hope they dont take too long only to tell me its all ok!

 

Thanks, I wish there was someone closer who was familiar with VAG COM just to run though it with me the first time.

[skinner2k3 3]

The car has been to VW and they found nothing which could cause the mechanical knock I experienced but they did find the cause of the light. It is the Yaw rate sensor. It is giving an implausible signal.

 

Not great news as it is a £800+ job!

 

I can simply switch the ESP off and not use the system, but when I want to fix it its going to be expensive.

 

Still not happy with the knock though.

[skinner2k3 3]

Looking around a clunking when the ESP malfunctions is normal, so it is related.