ABS Problem E30 325i 1990

[e30-wheels]

Firstly i found the abs warning light had been wired into the oil pressure light system i found this when i took the cluster out to do another job, this i disconnected but the light stayed off then i found the fuse link in the relay by the glove box was broken, this was fixed and the abs light came on i then found two abs wheel speed sensors were u/s (open circuit) these have been fixed but the abs light is still on, I have not checked any thing else yet as i have no technical information. Regarding the abs unit itself it has 1, 6 pin relay fitted i don't know if this is correct or should there be two relays fitted ? Any help would be very much appreciated.

Thanks

[Brianmoooore]

There should be two relays under the top cover of the ABS pump.
Note that front ABS sensors are handed, and the system will not work if they are on the wrong sides.

[e30-wheels]

Looks like thats the problem, Thanks

[Brianmoooore]

You can connect an AC voltmeter to each sensor in turn, and spin the relevant wheel. Each sensor should give a similar output for a similar speed of rotation.

[e30-wheels]

I have checked the resistance, all the sensors read between 980 and 1005 omes, i will check the voltage as well while i am waiting for the missing relay to arrive.

[e30-wheels]

Brian how do i tell which is the left and right sensor on the car?

[Brianmoooore]

If the resistance readings are OK, and they don't give a significant voltage when the front wheels the spun, then they are on the wrong side.
Can't remember if this applies to E30 ones, but some (at least) BMW sensors have a short raised line on the business end of the sensor, which fits either in line with the axle or at right angles to it.
Can't remember which way around this is either!

[e30-wheels]

Ok thanks, i must say i have not a problem on my 1986 E30 unless i have just been lucky when fitting sensors over the years.

[daimlerman]

Seem to remember that there's an L and R on the casting,and the part numbers will be different.

[e30-wheels]

Go hold of two good used front sensors but cant read the numbers or any indication which is left or right but they are handed, when placed together the fixing screw holes are opposed, the person i got them from also a zone member had marked them LH and RH. Just for reference when fitted they are very close to the suspension leg fit them the other way and there is quite a gap between the sensor and leg. Just waiting for the missing ABS pump relay to arrive and hopefully it will all work OK that is providing the left and right marking are correct.