re abs light not working

[popupstands]

I need to get car through mot, abs light not coming on, so could someone let me know how easy it is to run off oil light, help its going in for mot monday

[Davenotouring]

If it's not coming on AT ALL then they may not notice.

If it's coming on and staying on I think that's worse?

Which did you mean?

[Brianmoooore]

Davetouring, the ABS system itself is not testable for MOT, but the action of the warning light is. It's supposed to come on with the ignition, and go out after the engine is started - a bit like the oil pressure light.
Popupstands, theABS light is a seperate lampholder with wires connected to it, that pushes into a hole at the back of the instrument cluster. The MOT trick is to take this lamphoder (or a similar one - I think the rear ashtray lampholder will fit) and wire it in parallel with the oil pressure light. You wiil have to remove the cluster to do this.

[Davenotouring]

If you cover up the ABS stuff under the bonnet and if the bulb isn't working maybe they won't notice at all. Depends where you take it I guess!

[Brianmoooore]

.Just noticed yout OP says light not coming ON, not failing to go off. Have you tried a new lamp?

[popupstands]

Yes I have replaced bulb

[bosshogg]

Yes I have replaced bulb

Just had loads of problems along the same lines with mine, if its not the bulbs, before you do anything major check the wiring for the brake pad wear sensors, mine was a broken wire to the front nearside pads it took ages to suss it out as I was told the ABS was a seperate system to the wear sensors and spent ages barking up the wrong tree so to speak thanks to duff info.
PS hello Scott Burriss if you're reading this

[Brianmoooore]

There is no connection whatsoever between the brake pad wear indicator system and the ABS system.

[bosshogg]

can only say that once I replaced the broken wiring the abs system lights came on and haven't given any trouble since

[Brianmoooore]

Sure it was the pad wear wire you were repairing and not the ABS? They both follow the same route down the left front suspension to the hub.

[Jackle]

I syand to be corrected, but I believe you will only fail the MOT if the ABS is deemed to be faulty ie light comes on and stays on. If the light doesn't come on at all the ABS is deactivated and so connet be faulty and will therefore pass.
I had the same thing on my car, on further investigation it turned out that there was a relay missing from the ABS unit in the engine bay - I replaced it with a new one and also replace the relay above the glovebox, but the light just came on and stayed on. I haven't had time to investigate this more so I just took out the missing realy and left it. It's passed 2 MOTs like this so far

[RICHIE74]

Hi I work in a garage and for an M.O.T if a car is fitted with ABS , the warning light on the dash must come on with the ignition and go off when the engine is running , similarly to your oil pressure light . It will fail its M.O.T if either the light stays on when engine running or if light doesnt come on . Admittedly if the tester doesnt notice if the car has ABS and the light doesnt come on then it will pass . But i would be surprised if a tester didnt notice ABS rings and the pump etc . When i bought my 325 sport the light didnt work so i took out my clocks and found the bulb was missing , replaced the bulb only to find the light stayed on . In the end the fault was with a relay in the glovebox just above the silver control box .

[Jon_Bmw]

Hi I work in a garage and for an M.O.T if a car is fitted with ABS , the warning light on the dash must come on with the ignition and go off when the engine is running , similarly to your oil pressure light . It will fail its M.O.T if either the light stays on when engine running or if light doesnt come on . Admittedly if the tester doesnt notice if the car has ABS and the light doesnt come on then it will pass . But i would be surprised if a tester didnt notice ABS rings and the pump etc . When i bought my 325 sport the light didnt work so i took out my clocks and found the bulb was missing , replaced the bulb only to find the light stayed on . In the end the fault was with a relay in the glovebox just above the silver control box .

Richie what problem did you have? My 325 when the light stays off driving(random) when i come to about 5mph the abs seems to want to fight the braking of the car-i lose almost all brake power. If the light comes on and stays on the problem does not occur but the abs doesn't work hence it can lock up easily if the pedal is jammed hard.

What relay was this, and how did you narrow it down to that?

Cheers
Jon

[popupstands]

does anyone have wiring diagram for abs?

[RICHIE74]

Hi Jon . There was no problem with my ABS system as such , it was just that when i bought the car i noticed the light wasnt working . I took the clocks out and realised some shyster had removed the bulb . I put a bulb and and the light stayed on . I found out about the relay from this sight as it seems to be a common occurence . Dont think your fault lays with the relay though , it sounds more likely to be either a damaged ring or sensor . Sorry to take so long getting back to you , I have limited access to internet ( work computer )

[Brianmoooore]

It's likely to be a wheel sensor if the ABS light comes on with the ignition, goes out when you start the engine, and comes on again when you exceed about 5 MPH. This would not result in a MOT failure, because there is no road test involved and the light would not come back on.
ABS wiring diagram (for US models) is on www.diakom.ru .

[popupstands]

are they any experts in east sussex area that know about abs for e30

[Jon_Bmw]

Thanks for your input richie and brian, i cleaned up both the front sensors at work the other day, re-inserted them and it didn't help. The light is pretty much on all the time now, well once going over 5mph. Might pop down the scrappies and see if i can get a couple of sensors.

I had a look at the rear sensor/s are they in-built into the hub?? I couldn't find an easy way of taking these out.

[ian332isport]

Thanks for your input richie and brian, i cleaned up both the front sensors at work the other day, re-inserted them and it didn't help. The light is pretty much on all the time now, well once going over 5mph. Might pop down the scrappies and see if i can get a couple of sensors.

I had a look at the rear sensor/s are they in-built into the hub?? I couldn't find an easy way of taking these out.

Jon,

It's not so much the sensors that need cleaning, as the toothed wheels that they look at. If they get full of gunk, or really corroded, the sensor cannot get a decent reading.

Ian.

[Jon_Bmw]

Thanks for your input richie and brian, i cleaned up both the front sensors at work the other day, re-inserted them and it didn't help. The light is pretty much on all the time now, well once going over 5mph. Might pop down the scrappies and see if i can get a couple of sensors.

I had a look at the rear sensor/s are they in-built into the hub?? I couldn't find an easy way of taking these out.

Jon,

It's not so much the sensors that need cleaning, as the toothed wheels that they look at. If they get full of gunk, or really corroded, the sensor cannot get a decent reading.

Ian.

Is there anyway of cleaning these, am I right in thinking that the toothed wheels are built into the hubs??I don't think that squirting brake cleaner or alike is gonna cut it really. Not having abs isn't a good thing on a fairly powerful car.

Any help/advice always apreciated.
Cheers jon

[ian332isport]

It's while since I had that bit of the car apart, so cannot remember how much access you have while the hubs/bearings are fitted on the stub axles.

If push comes to shove, you could use a screwdriver through the hole the sensor normally mounts in. You just need to make sure the teeth are well defined and actually have a space between them.

If you have badly rusted teeth, then you may need to replace the bearings to get new ABS rings.

Ian.

[Brianmoooore]

If the light stays out until you reach about 5MPH, then it almost certainly a problem with one of the wheel sensors or it's wiring. It's possible to see if there is an output from a sensor using an AC milivoltmeter and spinning the appropriate wheel.