Technical ABS activating under light brakeing

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Technical ABS activating under light brakeing

john55

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I intermittently get the ABS pump activating (I can feel it through the brake pedal) under normal or light braking. I also get ABS/ ASR failure warning coming up intermittently after driving for a bit (Not at the same time as the ABS is activating), usually on a corner, U turn etc. I have cleaned all the connectors in the system, removed the ABS sensors themselves and cleaned them. I don't get any warning on startup, just randomly later on. It could be after driving 10 meters, or 50 miles. I have checked the brake lights and they work normally so I dont think it is a switch problem. I have even taken each wheel off in turn, turned the wheel and heard the beep-beep of traction control actvating, then pulled and twisted the wire to each ABS sensor but have not been able to get a failure by doing this.

Any suggestions?
 
Have you done a recent pad change and not clamped the brake hose before pushing the piston back in..:chin:
 
Are all the castalations clean where the sensor
heads are on each wheel hub?

Does this system have any ABS relays or is
it all computer boards now. If no relays check
any cable joints joints in the system.

John
 
Are all the castalations clean where the sensor
heads are on each wheel hub?

Does this system have any ABS relays or is
it all computer boards now. If no relays check
any cable joints joints in the system.

John

That was my next thought, but it involves taking the drive shafts out. I will do it if you think it is likely to be the cause but it is a bit of work.

Also I have already been through all the connectors in the system. No relays. ABS is directly wired to the battery at all times on a Stilo.

and no, I haven't recently changed the brake pads.
 
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As it's not there at start up, acts at random and when you turn corners/ U turns, have you checked ABS earth point C12?

Does warning light happen only when you are using the brakes or does it trigger even when not using them?
 
As it's not there at start up, acts at random and when you turn corners/ U turns, have you checked ABS earth point C12?

Does warning light happen only when you are using the brakes or does it trigger even when not using them?

C12? where is that. I can have a look at it.

Just had a nasty thought. It is probably the steering angle sensor playing up.
 
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I have checked the brake lights and they work normally so I dont think it is a switch problem.
Any suggestions?

My brake lights were working normally but I still needed a new brake switch to stop the "Christmas tree lights".

It was the same as yours, could be driving for 10 meters or 50 miles before it all lit up. I always lost the cruise control aswell on mine.

Dave.
 
Have you done a recent pad change and not clamped the brake hose before pushing the piston back in..:chin:



Just out of curiosity, how does this make a difference? can the reverse pressure damage the stilo? on most cars this isnt a problem so i want to know before i accidently do it in the future haha. :yum:
 
If you clamp the hose and open the caliper bleed nipple then you squirt the dirty and contaminated fluid that's been in the caliper for years out and gone rather than back up through the system. ABS unit also doesn't like hydraulic back pressure being applied through its little valves

abs electrics 1.JPG
Here's ABS earth point C12
 
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I seem to have fixed something. While my brake lights are working normally, I decided to pull down the brake switch plunger. It immediately went click click back in when I released the brake pedal and made no difference to the brake lights, but I have not had the ABS/ ASR failure since. Not driven it a lot, but touch wood, it is working.
I still get the intermittent ABS activation under normal braking, but I think I may have to disassemble the hubs and clean the ABS pickup rings to cure that.

With regard to the earth points, they are fine. I went around the engine bay about a year ago and cleaned/ copper greased all the earth points asd they look OK. I tried wiggling them with the engine running, but it did not cause any Beep Beeps's.

Thank you all for the replies.
 
john55 sounds like a good idea if you took some photo's of the hub removal and ring clean and put them in the guide section (y)
 
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