ABS related problem

[Eggert]

Hello guys,

I've done a bit of research and didn't find much. Hence this thread:

My 2001 4.4i has an error, it says rear left abs sensor is faulty. However, when reading status in INPA, I get a slower and more irregular pulse from the wheel, causing the ABS error to appear and disappear every few minutes of driving. The "BRAKE" light goes from red to yellow and back all the time, so I'm having hard time believing it to be the wheel speed sensor itself.

This started happning soon after I had both rear wheel bearings replaced. I noticed this after 100-200 miles of highway driving the following day.


So, I was wondering, is there any way to tell if the bearing itself is faulty? It is supposed to be from a reputable manufacturer, can't remember the name though.

What is the next step in diagnosing this fault? Any input appreciated.

[Eggert]

I just had it confirmed, the bearing is manufactured by FAG in Germany and chances of it being faulty is zero to none, or so the seller says.

When reading status in INPA it is like I'm only getting every other signal through from that wheel, other wheels report rotation normally but the rear left wheel status bar is jumpy.


Does anyone have any insight for me?

[upallnight]

Most likely the wheel sensor was damaged during the wheel bearing replacement, if the mechanic left the sensor in and didn't remove it. Just replace the sensor.

[sew]

I'm afraid I'd just be pragmatic on this one. The sensors *do* go wrong. They're not that expensive. I'd just replace the thing first and worry about further diagnosis if and only if the fault doesn't go away ... which it probably will...

[Eggert]

I understand. But what I was trying to get across earlier is that the pulse is consistent (which would make you think the sensor is ok?) at supplying (roughly) half the pulse that is normal.

But nevermind, I will change the sensor and report back, if only for it be helpful to someone else another day.
Let's hope it's just the sensor.

[sew]

I'm struggling to see what else it could be apart from the wheel speed sensor, unless it's the DSC module itself gone wrong. And I know what I'd sooner replace!

[Eggert]

Yeah, let's hope it's not the DSC module, I've already had my share of shipping modules to the UK for repair...

[upallnight]

Could be that whoever installed the wheel bearing, might have installed it backward. On some BMW the tone ring for wheel sensor is built into one end the wheel bearing. If your X5 have this type of wheel bearing there's a right way and a wrong way to install the bearing so you won't have ABS problem afterward. Here's a link:

https://www.youtube.com/watch?v=m3dgrgmMZw0

[Eggert]

It is not possible to install the wheel bearing incorrectly on the X5... our wheel bearing is different to the ones on your X3.