Braking System

[chesh100]

Hi,

I'm having a bit of a brake problem, have read a lot of the posts and have a few ideas, but could do with a bit of advice.

 

My problem: ABS warning light sometimes stays on. - I belive this to be a bad connection on the N/S/F.

Main problem is when the ABS light doesn't come on, sometimes at slow speeds (about 5 mph) when I touch the brake pedal it pulsates and a grinding noise can be heard!

 

I am thinking it might be air in the ABS pump and intend to bleed the system at the weekend, I don't have a manual and am unable to look at a schematic of the brake system to work out what the best way to approach the job.

 

Can anyone advise please or have any other suggestions as to what is going on.

 

Thanks

Chesh100

[Masked Marauder]

The first thing to check is that the ABS ring has not come loose on the CV joint.

[chesh100]

I checked them after reading the other posts, they're ok.

[Masked Marauder]

It is clearly a sensor problem then. Bleeding the brakes won't help.

[sepulchrave]

I'll second that, definitely a sensor problem. Try cleaning the plug and socket with contact cleaner and connect and disconnect a few times to clean the contacts, TBH the sensor wires tend to fracture right near the plug.

[chesh100]

Right update!

 

Checked all sensors and they are all close to 1ohm. Think the N/S/F has been the culprit.Every time the lights come on disconecting and re-connecting seems to re-set the system.

 

What I'm, confused about now is as follows:

 

From reading all the different threads about brakes, the system appears to send a signal when the vehicle first moves away when the speed reaches about 12-14 mph. At this speed I can hear what is best discribed as a "grinding" noise, thought it was supposed to be "clicking". Most of the time this is all that happens and the brakes work correctly. Occasionaly though, this "grinding" can be heard occuring at about 30 mph, and shortly after, the warning light will come on again. Quick disconnect and re-connect puts it all back to normal for a while.

 

The question is, is it the sensor that's causing the problem or, because of the "grinding" thats occuring, elsewhere in the system? and what is it? Any ideas?

 

Thanks in advance

Nigel

[Masked Marauder]

I still think it is the ABS ring on the CV joint...

[chesh100]

I've looked at the ring and can't see anything wrong. It's not loose or cracked, I've given it a clean.Anything else I should be looking for on it?

[Masked Marauder]

As long as it goes round with the joint it should work fine.

 

Short of hooking up VAG-COM, I don't know what else it could be.