ABS Fault, 325i

[ETERNITY]

e30 325i sport

ABS light on

relays replaced

any ideas

[Brianmoooore]

Light on when?
What relays replaced? There are three.

[ETERNITY]

light on when engine on

not sure what relays been replaced, will find out

[Brianmoooore]

light on when engine on

Still not accurate enough!
Are you saying it's not on with the ignition on, but only on with the engine running?
It's impossible to give accurate advice without accurate and detailed input.

[ETERNITY]

two relays on top of pump

lights stays from the moment you start

[Grrrmachine]

Have a read of this:

http://www.e30zone.net/e30zonewiki/inde ... n_Problems

[ETERNITY]

abs controller unit ?

[Grrrmachine]

ABS controller unit what?

You really need to speak in sentences for us to know what you want.

[ETERNITY]

I think it may be the ABS controller

thanks for the replies

[Grrrmachine]

Well, work through the steps as outlined in the Wiki and report back first. What makes you think it's the ECU?

[ETERNITY]

because relays have been changed

wheel sensors fine

[Grrrmachine]

So does the ABS system actually work? If not, how do you know the wheel sensors are fine?

[ETERNITY]

ABS does work on the front left but not the front right.

[Brianmoooore]

because relays have been changed

All three?

[ETERNITY]

no just the two near the pump

[Brianmoooore]

The two in the pump rarely give trouble. The one you need to change is just to the right of the ABS ECU, but fairly well hidden. It's not 'failed' as such, but died doing its job, protecting the ECU from harm.
Been doing anything with jump leads lately?

[ETERNITY]

Ok I dont have this car in my possession, so bear with me.
It has failed MOT becuase of this fault and I just bought it.

http://www.e30zone.net/modules.php?name ... c&t=218620

Its with the mechanics of the current owner at the moment, and he cant work it out.

However I do know that the batt has been replaced so I assume that the previous batt was faulty and must have been jump started a few times before the replacement

I get the car tmoz without MOT and want to get to get to the bottom of this so I can it have pass MOT when I get it.

[ETERNITY]

The two in the pump rarely give trouble. The one you need to change is just to the right of the ABS ECU, but fairly well hidden. It's not 'failed' as such, but died doing its job, protecting the ECU from harm.
Been doing anything with jump leads lately?

ok this is one I need to replace

can any one get me a part number and location of this relay.

thanks

[Brianmoooore]

The one you need to change is just to the right of the ABS ECU, but fairly well hidden.

[fixedwheelnut]

Number 13 in this link and that is roughly where it sits as well, on top of the bracket by the Glovebox catch
http://www.realoem.com/bmw/showparts.do ... g=34&fg=20

[Barx325i]

if this is an MOT worry, it's widely accepted to remove the cluster bulbs.

my first 325i had insulation tape on the cluster perspex, but I'm not convinced this will fool my MOT man

[ETERNITY]

if this is an MOT worry, it's widely accepted to remove the cluster bulbs.

my first 325i had insulation tape on the cluster perspex, but I'm not convinced this will fool my MOT man

the front right abs system doesnt work

so needs to be addressed

[Barx325i]

sure, I agree, just prematurely thowing a potential headache some paracetamol. Hope you get it sorted

[ETERNITY]

yes not even got the car yet

just want to get it sorted to pass MOT.

Would be even more frustrating not to drive it and see it sat there in the drive because apparently it drives amazingly well according to people that have had any contact with car.

[Barx325i]

well, I've thrown temptation your way

[Grrrmachine]

Fairly sure if he takes it for an MOT and gets the ABS kicking in on one wheel and not the other during the brake test, then he'll get the book thrown at him.

There's very little we can recommend if you don't actually have the car in your possession yet. Just work through the steps as you go.

If you're passing this advice on to the current owner, has he done a resistance check on each of the sensors to confirm that one of them isn't duff?

[ETERNITY]

I am just doing research before the car arrives because its coming on a transporter.

This info is for me because I am wanting an MOT on day 1 when it arrives

[ETERNITY]

Its very rare for Brian Moore to give wrong info in my experience so I trust its the relay

[Grrrmachine]

Relay is a common thing to check. But the next in line is dirty or damaged rings, then a failed sensor or wiring to it, so if you want your MOT on day 1, you'll need to be prepared for those eventualities.

I wrote the Wiki page for the ABS less than a month ago, so the pages and pages of threads I read about "ABS NOT WORKING" are still very fresh in my mind

[Barx325i]

not necessarily the book, in the UK they don't test specifically for the ABS inception point.. It's only braking force across the axle they're concerned about, the only indication the MOT man has to identify an ABS fault is a warning light or the specific duration of the POST process but I don't suggest for a second this should be overlooked..

[Brianmoooore]

ABS doesn't have to work to pass a UK MOT test, even if it is fitted. The only part of the ABS system that has to work and behave as it should is the warning lap.
A sensor fault on an E30 ABS system won't be detected until the car is moving, and the ECU detects no or an implausible signal from a sensor.

[ETERNITY]

my best bet is to start with relay like brain said

then take it from there

[ETERNITY]

ABS doesn't have to work to pass a UK MOT test, even if it is fitted. The only part of the ABS system that has to work and behave as it should is the warning lap.
A sensor fault on an E30 ABS system won't be detected until the car is moving, and the ECU detects no or an implausible signal from a sensor.

Brain can you just confirm these symptoms mentioned lead to the faulty silver relay in the glove box or should I look and test the sensor/wiring.

Its the right hand front side that doesn't work

I should have the car with me on Friday afternoon

can confirm that jump leads have been used

thanks once again

[Brianmoooore]

If the light doesn't go out when the engine is started, then the fault is probably that the 'relay' has done its sacrificial job of protecting the ABS ECU from someone using jump leads incorrectly. This doesn't mean that there can't be a second sensor related fault, of course.
To test to see if the 'relay' is at fault, unplug it, then link together first the brown and brown/yellow and then the red and red/yellow wires of its socket.
Start the engine and check that the ABS light goes out, then drive the car and check that it stays out.
Switch off the engine, pull out the wire linking the red and red/yellow, then the other one, or you will get a flat battery.