ABS comes on after wheel bearing change

[fordy52]

Hi I wonder if anyone has had this problem I changed the front wheel bearings on my car (a bit of a *** to do) but after putting the wheels back on went for a test drive 1min down the road the ABS kicks in for 30sec slows the car down then go`s off and all is OK until you switch off the engine and try to pull off again same again , thinking the bearings may need to bed in ran the car for a week or so but after the car is switched for any length of time and restarted you start to pull away the ABS comes on for that 30sec
Thinking I may have damaged the ABS sensors I changed them both ( that's a job & a half ) but this has not sorted the problem both wheels are free when you jack the car up so am at a loss now, please help someone
Graham

[C.Noble]

I suspect you have either damaged one of the impregnated discs on the back of the wheel bearings, or one of them is faulty.

The ABS sensors detect wheel speed from tiny magnets 'impregnated' onto the little black disc that is attached to the weather seal/cap on the back of the wheel bearing, this disc is very easily damaged, even a little score that is deep enough to go through to the silver cap beneath will be enough to render it useless.

hope this helps.

[fordy52]

Thanks for the post, from what I can remember the only thing on the back of the wheel bearing was a weather seal on both of them and there was no damage to ether one, so all I can think is one of the bearing has a fault. Is there a way to check said bearing to find which one is at fault or will the diagnostics on the car tell me this

[C.Noble]

The only way to check which one is at fault is to plug in, there must be a code stored as the light has come on. I would suspect you will have something like a "coherence fault" or "run up correlation fault" on one wheel, as opposed to a sensor open circuit fault... there is where your problem will be.


If you have replaced the sensors before (which I see you have) it would be a good idea to note the codes stored, erase them and road test your MINI again to bring the light on and read the codes again to see which one returns, this way you will know which code is relavent and wont chase your tail on codes generated from before.

[mella yella fella]

not sure if this applies to mini bearings, but on some french cars where the abs picks up off the bearing instead of a reluctor ring on the driveshaft, the bearing must be fitted into the hub assy one way only.if its oin the wrong way round, it wont pick up the alternating signal required.