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[Sir Tigger KC]

My ABS lights come on after a few miles every day. 

Following a guide on Bimmerfest I tested the sensors from the plug at the ABS ECU with my multi meter and the front offside was the only one that I couldn't get any sort of reaction from.  My local garage plugged their code reader in and said it was the front nearside. 

I got a BMW sensor from the local scrappy, but no joy and today I've tried a cheap £10 pattern sensor on both front wheels and the light is still on.   

Given that a new BMW sensor is £108 I'm reluctant to buy one unless I'm 100% certain that it'll sort the problem, hence the pissing around with second hand and cheap sensors.... 

The other thing of course is that it's the ABS ECU playing up which is apparently a well known fault as they're located by the exhaust manifold.  So I could whip it off and pack it off to BBA Reman..... 

Any advice would be gratefully received! TIA! 

[henryd]

My ABS lights come on after a few miles every day. 

Following a guide on Bimmerfest I tested the sensors from the plug at the ABS ECU with my multi meter and the front offside was the only one that I couldn't get any sort of reaction from.  My local garage plugged their code reader in and said it was the front nearside. 

I got a BMW sensor from the local scrappy, but no joy and today I've tried a cheap £10 pattern sensor on both front wheels and the light is still on.   

Given that a new BMW sensor is £108 I'm reluctant to buy one unless I'm 100% certain that it'll sort the problem, hence the pissing around with second hand and cheap sensors.... 

The other thing of course is that it's the ABS ECU playing up which is apparently a well known fault as they're located by the exhaust manifold.  So I could whip it off and pack it off to BBA Reman..... 

Any advice would be gratefully received! TIA! 

If the light goes out initially then comes on when driven its more than likely to be a reluctor issue(sensor can't read the rotor at speed)

often throws a different code ie Coherence

[Sir Tigger KC]

So a quick Google suggests I can clean the rings with brake cleaner through the sensor hole? 

[Doctor Gollum]

So a quick Google suggests I can clean the rings with brake cleaner through the sensor hole? 

Later ones are sealed into the back of the bearings...

If yours has blue plugs then it's later...

[Sir Tigger KC]

That doesn't sound encouraging...... 

[Doctor Gollum]

Imagine the castellated abs rings on the Omega, coated in a layer of resin... You can make out the peaks, but you can't really feel them.

In theory it should be next to impossible for dirt to affect them

[Sir Tigger KC]

I've never looked at reluctor rings before so don't know anything about them.... 

I'll have another look at the weekend.... if it's dry! 

[Doctor Gollum]

A picture paints a thousand words...

http://www.ebay.co.uk/itm/for-BMW-5-Series-E39-530i-535i-540i-Front-Wheel-Bearing-HUB-31221093427-/231652258163?fits=Car+Make%3ABMW%7CPlat_Gen%3AE39&hash=item35ef8cf173:g:piYAAOSwBOtY93d1

I will be down in the New Forrest over the weekend if you need codes cleared/read... subject to boating and drinking schedule

[henryd]

A picture paints a thousand words...

http://www.ebay.co.uk/itm/for-BMW-5-Series-E39-530i-535i-540i-Front-Wheel-Bearing-HUB-31221093427-/231652258163?fits=Car+Make%3ABMW%7CPlat_Gen%3AE39&hash=item35ef8cf173:g:piYAAOSwBOtY93d1

I will be down in the New Forrest over the weekend if you need codes cleared/read... subject to boating and drinking schedule

Active sensor bearings so no abs rings as such,Had a few lately(not bmw) where the seal/sensor had deteriorated to the point where the sensor couldn't read it,ABS light would go out at start up but come on at around 20-30 mph

[Doctor Gollum]

Mine is consistently logging 95 Canbus signal error on the gearbox ecu... rest of codes for both abs and box vary... as do the failure modes... always starts with the abs going off but otherwise the cruise may or may not work, likewise the gearbox- won't change up automatically or goes into either third or fourth with no manual control.

Only common denominator is the abs ecu, and unlike the Omega, it's a question of when, not if, it fails

[Sir Tigger KC]

I had a go at cleaning the front reluctor rings this afternoon, which I did by stuffing a rag through the sensor hole and wiggling with a screw driver while spinning the hub. I also tried some cotton buds.

The nearside seemed have plenty of crud and I cleaned it all out as best as I could and put the new sensor on.

The lights came back on about 6-7 miles down the road. 

[Viral_Jim]

The lights came back on about 6-7 miles down the road. 

Now that is cruel! I bet that was just far enough for you to think you'd cured it!

[Sir Tigger KC]

Yes my hopes were rising and then when I pulled up at a junction I felt the familiar shudder from the brake pedal and the lights came back on to mock me! 

I'm wondering if the bearing is leaking grease onto the reluctor ring and so the sensor can't read the wheel speed as Henry suggested earlier. 

[henryd]

Yes my hopes were rising and then when I pulled up at a junction I felt the familiar shudder from the brake pedal and the lights came back on to mock me! 

I'm wondering if the bearing is leaking grease onto the reluctor ring and so the sensor can't read the wheel speed as Henry suggested earlier. 

The rear seal on the bearing is the reluctor ring and they do deteriorate with age,code reader should tell you which wheel is the cause

[Sir Tigger KC]

Yes local garage said it was the nearside which was the side which I removed the most crud from.  Seems that's the answer then.