liveinadive1

Interesting.
I think this weekend I may just have a look at all the sensors, see if there is any noticable difference then give them a full clean up.
It seemed odd that I was getting 3 identical readings and one off so perhaps it is the wrong sensor fitted or something. The car has had this issue since I got it so it could be that.

Sysgen

Hum, that's good to know! I still have random moment where the ABS disables itself, that could be it. I've been looking for 4 known good sensors to replace them all at once but can't find any.

Anyone?

liveinadive1

Just a thought. My brake pipes, lines the lot are looking a bit crusty too, any chance that could be effecting the ABS system.

I am planning on replacing them but wanted to sort this ABS stuff first.

924RACR

Actually... you should consider that the pump motor relay could be failed... after all, replace parts in reverse order of cost! Not to mention fuses...

With a shorter protruding pickup, the air gap on the sensor will be larger, which means that the signal may be weaker. This may or may not pass the drive-off tests, but it can also be expected to be more sensitive to faults while driving - plausibility and signal drop-out checks.

Brake hard line corrosion should make no difference to ABS unless you have a bad ground, or up until the point that they burst!

liveinadive1

Cheers for the help guys.
As 924R suggested I went in reverse cost order.

Tested the relay using wire wrapped and taped around the connectors and it read negative. Picked up a second hand relay of the 'bay for £25 which seems to have sorted the problem out, I couldn't get the error light to come on even testing with heavy braking and the ABS kicking in.

Good times

hacker-pschorr

Nice work, I wish new(er) cars were so simple. Even when the factory computer tells you X sensor is bad, half the time it's wrong. Especially with BMW's.

Very frustrating.

Boogieman

Very nice description

I have another ABS problem (i think). I got some parts on my exhaust welded and after that my ABS is not working BUT I do not get anny error indication from the ABS lamp?

PROBLEM DESCRIPTION
I turn ignition on - ABS lamp lights up
Start motor - ABS lamp goes out imediatelly
Drive - ABS light still out
Brake hard - wheels lock up - ABS light still out

Could it still be a sensor or do you think they fried the box when welding?
Also my oil sensor died the same time - before it was a bit jumpy (somtimes dropping quick to 0 bar and then back up after 0.2sec) so it could just be coincidence.

I have the left hand drive (European version) so I guess the box is on the other side?
Would the pin nrs be the same?

Thank you
Ola

Sysgen

It's possible they fried it when welding but then again, the board might have died of old age. Try changing the ABS module, they are not too expensive on e-bay. I don't think a sensor would do this, if a sensor is not detected, it turns on the light when you start moving.

If you changed the relay, then in order I would check the ABS module then the pump.

djantlive

Sysgen - this old thread helped me tremendously to resolve my ABS light issue which I have been trying to resolve for about 2 months now. it turned out to be a poor contact between the ABS computer and the electrical plug. I was relieved that no speed sensors were bad using your test method.

Just wanted to thank you for this great contribution.

Sysgen

Glad it helped you and a big thanks for the feedback

armandodiaz

I've noticed most of the issues have to do with the light coming on after the car starts rolling.

With my 951S, the lights (both the anitlock and the !) comes on as soon as I turn the key and never turn off. The car was stationary for about a month and I had rebuilt the head. Any suggestions?


Thanks

Sysgen

Check the abs fuse then try to swap the abs relay. When i pull the abs fuse at the track that's what it does.

armandodiaz

Checked the fuse (good) and there's pwr at terminal 30 at the relay. I don't have a spare relay, but I took the old one off and jumped terminal 30 and 87. When I jumped them I heard clicking from the right side of the car, I'm assuming this is the area of the abs pump.
Do you know of any way to test the relay?

armandodiaz

Well, I finally picked up a used relay (supposively good). Plugged it in and still got the same results.... both lights turn on with the ignition on and never turn off.
I'm going to go through the tests, mentioned on the original post. Just so I can rule all that out.
So if everything test OK, could it be the controller itself??? Has anyone had one of those go bad?

Bubby

I had to change the relay on the ABS pump sitting inside the right innerfender.. the thin wire on the coil on the relay was broken..