Calling ABS heros! Frustration now!

[Simon13]

Right got a funny one on my old sport

abs light goes out when engine starts like normal, drive 5 metres up the road and it comes on.

Now this car has 2 new wheel bearings and i've cleaned the front sensors up.

I can clean the rears also but if that don't work then

I've heard a resistor goes sometimes?

cheers

[Martinaston]

Check the resistance on all the sensors (1000 ohm's) could be the one nearest exhaust manifold when it gets warm.

[Simon13]

do i have to take the sensors out and test with a voltmeter ya?!

[Kos]

remove bulb from dash any your executive chariot will be sorted

[Brianmoooore]

Ignore Kos, and check the sensor resistances.
Two white connectors on the inner wings and two undwe the back seat.
Pull the connectors apart, and with a multimeter set to resistance, measure the resistance across the two pins in the sides of the connectors that goes to the wheels. Should all be the same and around 1000 ohms.
Two new front wheel bearings? They did have ABS rings on them, didn't they?

[Simon13]

they did Brian yes, because they tried to give me one without when i bought them!

The parts guy at my local dealer said it could be one of the relays on the pump? he said there are 2

Or is not likely with the symptoms i am describing?

cheers

[Brianmoooore]

Your symptoms are those of a faulty wheel sensor. The ABS fault sensing circuitry is happy untill the wheel sensors start producing an output, when it finds one is incorrect.
It's too much of a coincidence that this fault appeared at the same time as the front wheelbearings (and ABS rings) were changed

[Simon13]

The ABS was fine Brian after i changed the bearings.

One sensor had been cut through by some thing off the road don't know how. I've replaced this now, unless this is also a buggered sensor

This started when i changed the wheels a few months ago, took my pina's off and put some 15bbs

I can't comment any more until i do what u have suggested, i hope i find something out

[Brianmoooore]

Haven't got wheels with a different rolling radius at different ends of the car, have you?

[Simon13]

no i took my 16inch alpina's off and put 15 bbs on both sets with size correct tyres.

The difference in rolling radius on these two is about 0.3%

Getting my dads volt metre tonight so i'll have a go and see what i find

[ac]

Brianmoooore

I'm having the same problem but sensor resistance readings are between 1000 - 1400 are these right.

Thanks

Ac

[Brianmoooore]

It's possible that BMW used more than one manufactuer for ABS sensors, and a different make could have a different resistance, but I would expect all the sensors on a particular car to be the same and have identical resistance.
Normally, with a faulty sensor, you would find three the same and one different.

[ac]

That's what I thought. Only one was around the 999 mark and also the car has, new ap pads, new disk all round along with new shoes and the car it self has only covered 60,000 miles so kind of strange because I know that my abs dose not work at any speed along with the light going out and then back on. So I think it must be the abs unit but as soon as I find out I will let you all know.

ac

[andymn]

hi all,
i would just like to add to the ABS problem if thats ok.

when i brake slowly and come to a stop, i get a funny noise come from the front passenger side.

i thought it was the brake servo, but corky was in the car last night and it made this noise, he mentioned about this ABS thread and the sensors playing up.

any suggestions greatly appreciated

Andy

forgot to mention, i only get the oil light on the dash when ignition turned on, other lights remain out....

[ac]

I get the same but a small dong noise a slight up push in the brake pedal just before I come to a complete stop.

[Jon_Bmw]

hi all,
i would just like to add to the ABS problem if thats ok.

when i brake slowly and come to a stop, i get a funny noise come from the front passenger side.

i thought it was the brake servo, but corky was in the car last night and it made this noise, he mentioned about this ABS thread and the sensors playing up.

any suggestions greatly appreciated

Andy

forgot to mention, i only get the oil light on the dash when ignition turned on, other lights remain out....

Sounds like someone has taken the bulb out or removed a relay or something to cover the fact the abs doesn't work. The abs light should come on with the ignition and go out when you start the car. Does the abs work, go out and try and lock the brakes...but without some old granny behind you please, don't want another written off e30

This will see if the abs is either disconnected or not working, i would suspect a dodgey abs sensor, but don't go replacing parts straight away, do the resistance check first.

[Theo]

Whilst this thread is still current I would like to add a question of my own if I may.

My car has ABS, but there is no ABS warning light in my instrument cluster, or at least not that i'm aware of. Are there different clusters for cars with/without ABS, or is it another fault which I need to sort along with the pad wear indicator!

Thanks

[Brianmoooore]

Whilst this thread is still current I would like to add a question of my own if I may.

My car has ABS, but there is no ABS warning light in my instrument cluster, or at least not that i'm aware of. Are there different clusters for cars with/without ABS, or is it another fault which I need to sort along with the pad wear indicator!

Thanks

Your cluster has a position for an ABS light clearly marked on the back of the cluster, but the warning lamp itself is similar to the little lamps that light up the ashtrays and is on flying leads. It just pushes into the hole on the back of the cluster, and has to be removed the cluster is taken out.
It may be tucked in behind the centre of the dash somewhere.

[Theo]

Thanks Brian, i'll check it out.

[Simon13]

heros! checked the resistance on all 4 sensors today, all 4 are 1400 ohms!

i'm going to clean the rear sensors up and hope for the best. It must be something silly!

Thinking about it the car has has had 2 new front w/bearing and a replacement half shaft after a major CV joint failure. And the abs worked all throughout this work

[Kos]

Ignore Kos,

just a joke between mates!!!

[Simon13]

cleaned the rear sensors today no luck. I've swapped over both relays and no luck.

I'm drawing a blank on this now

Are the rear sensors supposed to look the same as the fronts or is the point on them shorter?

cheers

[boybimmerm3]

I have got an abs control unit if you want to plug it on and try it. Give me a call when you can.

[M5pilot]

You might need a new relay - it lives above the glovebox.

I had the exact same problem on my E30 and this sorted it. Relay cost me about £15 from BMW.

Not saying this is your problem but its worth a try if you can try the one from the C2.

[Brianmoooore]

Original post for this thread still suggests a sensor fault. The ABS is happy untill you move, and the sensors produce an output (or not, in the case of one).
Ideally you need a four channel oscilliscope connected up to the sensors as you drive.
You could connect a AC millivoltmeter to each sensor in turn, as you drive at the same speed each time and compare outputs.
Best place to connect the meter, would be to remove the ABS ECU, and connect to the pins in the socket.

Pins 4 and 6 are left front
Pins 8 and 9 are left rear
Pins 11 and 21 are right front
Pins 24 and 26 are right rear

[Jon_Bmw]

Si, can you not just quickly swap the front abs sensors from your old sport that is a min walk away, heck your brother in law won't even know if you did it cowboy style with a knife

I am tending to agree with brian on this, only because mine has the exact same symptoms and a new front abs sensor solved it, well second hand actually, taa nelly i think that was.

Takes two seconds to change them, go on it might just cure the problem

[Brianmoooore]

Takes two seconds to change them,

They're not always this co-operative!