ABS/ASC Light on....a common problem i believe!

[Kenhayes247]

Hello all,

So, after 3 and a bit years of overhauling/renovating my 2001 1.9 Z3 it is nearly ready to be put back on the road. Most of the underside components have been removed, cleaned, inspected and either repaired or replaced. The same can be said of the body work with the final piece being to have the bonnet re-sprayed.

Anyway, i decided to do a short (Private) road test before putting the car on the trailer and heading for the painters for the last time.

Just a few metres in and the ABS/ASC lights came on. I returned to my garage and using a Creative 310 Plus scanner it listed the following as faults:

Wheel speed sensor front right
Wheel speed sensor front left
Wheel speed sensor rear left

The front and rear sensors are all new, Non OEM - Delphi. Conducting a live stream shows that both Front L & R sensors are providing information when the wheels are rotating, when they are not rotating they show up as a fault. During the live stream the rear left was not sending information when rotating so i replaced it with the original old sensor the rear right was okay.

I cleared the faults went for a drive again and the lights stayed off. However now there seems to be a low buzz or judder felt through the brake pedal just as the car is coming to a stop. Braking normally is fine it is just as the car is about to come to a halt that the pedal starts to pulse really quickly as though the ABS has engaged.

I did another check with the scanner and the same 3 faults appeared as above but the ABS/ASC lights remain off. This time i removed the battery negative lead for ten minutes, reconnected it and went for a test drive, the ABS light remained off but the ASC light came on and went off after 2 or 3 minutes. The ABS effect i mentioned above is still happening just as the car again comes to a stop. Other than what is mentioned above there are no other faults showing.

Before all the work began there were no problems with either braking, ABS or ASC so i might go back to OEM with the wheel sensors. However before i do has anybody else had a similar issue?

Any input gratefully received.

Many thanks

 

[colb]

Given that the car has been inactive for a good length of time its probably had a shock with its reactivation, usual problem is as you stated duff wheel speed sensors which you have already tested. Could be a build up of rust on the recultor rings in the hubs that the sensors take their readings from as the gaps pass by the sensors. See if you can clean them without having to dismantle the hubs, think you may be able to see them with the wheel off and give them a scrape with a flat blade screwdriver. Rescan them with the Creator and ensure they are all reporting. As to the pulsing of the pedal, have you changed the brake fluid and bled the entire system, give that a go and drive the car to give the brakes some work to do so it cleans the discs up under some use.

 

[Kenhayes247]

Thanks colb,

Front wheel hubs, bearings and ABS rings are all new. No rust as the car is dry stored. I only put the front hubs on a few weeks ago. The rears Hubs similar story although the rings are original but totally clean. The pulsing of the brake pedal only started today once the ABS/ASC lights went off....strange i know.

During the overhaul I did let the brake fluid totally drain, would that cause a problem with the ABS unit/Pump? I bled the brakes the old fashioned way. Is there anything else i should have done with the ABS

 

[137699]

I have read of issues with pattern sensors which is why when one failed I stuck with OEM.

 

[Kh77777]

Hello all,

So, after 3 and a bit years of overhauling/renovating my 2001 1.9 Z3 it is nearly ready to be put back on the road. Most of the underside components have been removed, cleaned, inspected and either repaired or replaced. The same can be said of the body work with the final piece being to have the bonnet re-sprayed.

Anyway, i decided to do a short (Private) road test before putting the car on the trailer and heading for the painters for the last time.

Just a few metres in and the ABS/ASC lights came on. I returned to my garage and using a Creative 310 Plus scanner it listed the following as faults:

Wheel speed sensor front right
Wheel speed sensor front left
Wheel speed sensor rear left

The front and rear sensors are all new, Non OEM - Delphi. Conducting a live stream shows that both Front L & R sensors are providing information when the wheels are rotating, when they are not rotating they show up as a fault. During the live stream the rear left was not sending information when rotating so i replaced it with the original old sensor the rear right was okay.

I cleared the faults went for a drive again and the lights stayed off. However now there seems to be a low buzz or judder felt through the brake pedal just as the car is coming to a stop. Braking normally is fine it is just as the car is about to come to a halt that the pedal starts to pulse really quickly as though the ABS has engaged.

I did another check with the scanner and the same 3 faults appeared as above but the ABS/ASC lights remain off. This time i removed the battery negative lead for ten minutes, reconnected it and went for a test drive, the ABS light remained off but the ASC light came on and went off after 2 or 3 minutes. The ABS effect i mentioned above is still happening just as the car again comes to a stop. Other than what is mentioned above there are no other faults showing.

Before all the work began there were no problems with either braking, ABS or ASC so i might go back to OEM with the wheel sensors. However before i do has anybody else had a similar issue?

Any input gratefully received.

Many thanks

Yup, our 2001 Z3 has had the ABS sensor problem for years. Same thing where sometimes the light goes off and we get ABS activation at low speed stops. Usually for one or two stops then the light comes on again. About 10 years ago our repair person got a replacement ABS component (chip? Sensor?) from a Z3 in the scrap yard and it worked for about 3 months before the exact same problem came back. We gave up and drive now with the light on (and presumably no ABS). Just have to remember that pre-ABS driving lesson to pump the brakes ourselves when the need arises.

 

[Neilb62]

Use BMW sensors only, I had three Delphis from ECP trying to cure a DSC fault. A genuine sensor cured it immediately.

 

[Kh77777]

He claimed it was BMW sensor.

Interestingly this week I gave up on my partner’s old mechanic and took the car to the dealer. They got the ABS light off by “clearing the moisture off the speed sensor”?!?! We shall see what happens after driving it. But I got all the way home without the ABS light coming back on so fingers crossed.