Wooden Brakes

[Daniel]

Just been out for a spin and all of a sudden my brakes went wooden as if the servo stopped working. Brakes still work but you've really got to give them a good push.

The brake light also is now on.

I've had a faulty ABS sensor for a while now, could this be part of the problem?

Gutted as I'm doing a track day at Anglesey on Friday so need to sort it toot sweet.

Thanks in advance

[Jonathan]

Depends what system you have.

If you have a later post 94 S4 then the delco can disable the boost function.

1st check is to pump the brakes like a mad man and open the reservior to check what the fluid levels are - IF it is the delco system sometimes the partition stops the 2 halves of the reservoir from filling - i'm pretty sure the rear half is a reservoir for the rear circuit and the boost chamber.

A solid light also means you have a 'stop or else' failure - I'd sort that out asap if I were you.

Unlikely the ABS sensor is a problem - but get it fixed (not that expensive) as it can mask other faults that would normally use the fault light.

[Daniel]

spoke to PNM......top blokes as usual.

told me to tap the relay, and listen for a pump noise....which I did, and the pump set off and everything works fine, so it needs a new relay.

[Simon350S]

Sweet.......

That was a quick fix...

Hope they are all like that for you in the future... One to remember as well....

Should this be a Wiki thingy???

Simon

[Jonathan]

Aye that would do it - if the pump dont run you wont get any pressure in the boost chamber.

You can test the pump by switching the car on and repeatedly press the brake - after a few pumps it should wirr a little to maintain the pressure.

[Daniel]

yeah I've been doing that just to check it and free up the relay.......dont want to head into a corner on friday with dodgy brakes

[Jonathan]

All you'll lose is the power assist, a lot of poeple disable this ABS and drive the car fine, infact a lot of trackers dislike the control an ABS power assisted brake system offers and disable it becaise of that.

Just wondering if you can swap it over with another relay from a not so important service such as air con ?

[Daniel]

OK I've been out for a good run, and it keeps doing it, brake light comes on, lose brake effort.

If I give the vacuum motor a tap with a spanner it springs back in to life, works for a while then sticks again.

So it's a motor problem, I'm hoping PNM have one and can fit it tomorrow.

I've just got home and my GF kept depressing the brake until the motor kicked in, occasionally it stopped and the light came on, so I gave it a tap and off it went.

The car spend a lot of it's time stood in my garage, and things like this I guess happen.

As I left it, it hadnt failed to start 20 time on the run, but I cant risk taking it on track like this.

[superdavelotus]

Hi Daniel,

Saw your car today at PNM having the motor changed. Hopefully you'll be able to go on your track day after all!

If you are picking it up tonight, I might pop over to PNM to say Hi!

Dave Walters