[Tim G]

So out of nowhere these errors all pop up on the way home yesterday.

I know I need to read the fault codes, getting a reader asap to do so. In the mean time....

The only physical sign of something being faulty, is when I turn the steering and brake at the same time (from anything over about 10mph) the brake pedal vibrates gently for a about a second, and there is some sort of noise (almost sounds like a spring boinging I thought!). I assume related to abs/traction?

It doesn't do it when braking with the steering wheel straight, however hard I brake.

Anyone else had his issue with the same symptoms please? Fearing the worst!

[Cro]

Steering angle sensor, speed sensor, wheel bearing signals, bad battery and there's probably more that cause these things

[Tim G]

Noticed today that the cruise control no longer works ...

[tmarshall57]

Its very likely to be the ABS / Hydro unit but get the codes read to be certain. These are notorious for failing and, on 6 cylinder units, cost around £1800 to repair / replace using OEM parts. ECU Testing can repair for £250 or so. There are lots of threads on here if it proves to be the ABS including this from when I had my E90 330D....http://www.e90post.com/forums/showthread.php?t=813999

[Tim G]

Was reading through your thread after some searching earlier. Fearing the worst, but is there any detailed info anwhere on how to remove/refit the abs unit? How difficult is this?

[tmarshall57]

It is quite easy to remove the ABS Unit. Its located under the bonnet, close to the windscreen on the drivers side underneath a cover. There is a DIY here (note this is a US vehicle and the ABS Unit is on the nearside.

http://www.e90post.com/forums/showthread.php?t=600491

I removed the unit and sent the whole lot (both electrical and mechanical sides) to ECU testing.

The fiddly bit is removing the unit - the nuts are difficult to see and you need to make sure you don't let them drop off the socket and get lost.

Removing the unit from the car is fiddly because there are 6 or so brake lines making life difficult. You need to twist the unit around and simultaneously move the lines.

You need to be able to bleed the system after refitting the unit. Ideally you will need INPA or DIS V 57 to vibrate the valves during bleeding. Alternatively you could take it to an Indy and it will still be a substantially less costly solution than taking to BMW.

[Tim G]

Originally Posted by tmarshall57

It is quite easy to remove the ABS Unit. Its located under the bonnet, close to the windscreen on the drivers side underneath a cover. There is a DIY here (note this is a US vehicle and the ABS Unit is on the nearside.

http://www.e90post.com/forums/showthread.php?t=600491

I removed the unit and sent the whole lot (both electrical and mechanical sides) to ECU testing.

The fiddly bit is removing the unit - the nuts are difficult to see and you need to make sure you don't let them drop off the socket and get lost.

Removing the unit from the car is fiddly because there are 6 or so brake lines making life difficult. You need to twist the unit around and simultaneously move the lines.

You need to be able to bleed the system after refitting the unit. Ideally you will need INPA or DIS V 57 to vibrate the valves during bleeding. Alternatively you could take it to an Indy and it will still be a substantially less costly solution than taking to BMW.

Thanks for this, very helpful. I may well pick your brains if mine turns out to be this.

[Tim G]

Pulled the codes now.

Anyone had the same or shed any light?

Motor Control:
Engine / Motor
Fault: Message failure
Code: 49F2

ABS / DSC / Brake:
Dynamische Stabilitaets Kontrolle / DSC
Fault: Left front direction detection
Code: 5D96

[Cro]

Comes up as wheel speed sensor for me

[Aragorn30d]

49F2 is a code from the Engine ECU, where its saying its losing the vehicle speed signal message from the ABS unit.

5D96 is related to wheel speed sensors, specifically the front left one.

They're related, one imagines if the ABS system has decided the wheel speed sensors cant be trusted, then it shuts down the speed signal output to the ECU.

I would be inclined to check the reluctor and sensor on the front left wheel. Also check the wheel bearings for play on that corner.

[Tim G]

Can I ask where you are finding this info on the codes? I've had a quick search around ...

Links please for future reference!

[Aragorn30d]

I usually just google the fault code along with BMW, so "BMW 49F2" or "BMW 5D96" which usually finds other threads, information or descriptions of the fault codes.

The red herring here is that theres a known/common issue with the 6 cylinder E9x models where the ABS unit itself becomes faulty, and brings on those lights. As a result any time those lights appear, everyone jumps on that common issue. Simple fact is ANY ABS fault will bring on those lights, because with the ABS broken all those systems are taken offline.

Your car is pinpointing one wheel speed sensor, so before you start down the expensive path of condemning the ABS unit, you need to fully investigate what the ABS unit itself thinks is broken!

[Tim G]

If code 5D96 does indeed point toward a sensors, is this the correct part? I expected it to be called an abs sensor/ wheel speed sensor?


Number 7 - DSC Pulse Generator?

[Aragorn30d]

yeh thats the fella.

It might not be the sensor itself though, the ring the sensor reads from can become corroded and that can cause the issue, so that needs investigated when its all apart. Similarly a worn wheel bearing can sometimes cause enough movement that the gap between the sensor and ring moves around causing the readings to vary.

[Tim G]

Originally Posted by Aragorn30d

yeh thats the fella.

It might not be the sensor itself though, the ring the sensor reads from can become corroded and that can cause the issue, so that needs investigated when its all apart. Similarly a worn wheel bearing can sometimes cause enough movement that the gap between the sensor and ring moves around causing the readings to vary.

When you say all apart, is it a case of one bolt and pull the sensor out and then clean inside the hole? Or is there 'more to it' than that?

[Aragorn30d]

More or less yeh, but i dont know how accessible the reluctor ring is with the sensor removed.

This shows an example of a ring that has become damaged:

http://www.e39-forum.de/attachments/748.jpg

[Tim G]

Originally Posted by Aragorn30d

More or less yeh, but i dont know how accessible the reluctor ring is with the sensor removed.

This shows an example of a ring that has become damaged:

http://www.e39-forum.de/attachments/748.jpg

Hmm OK, thanks for that. My cars only done 70k miles, so I would hope it's not that. Not quite sure of the workings inside the hub, so can't quite work out how it would become damaged anyway!

I will try the clean up/ new sensor route first and then take it from there!

[Tim G]

So bought and fitted the sensor today. Opted to go with a meyle sensor from eBay for £25. Easy job swapping them over. Was very relieved to see all the lights go out when I started the car!

Total cost was £25 for sensor and around £60 for the Carly for BMW app and Bluetooth dongle so I could diagnose it (got loads of value out of this anyway with all the coding options I've been playing around with).

Thanks to those who offered their input in this thread.

[Aragorn30d]

Good work