Mini cooper 2002 Abs warning light

[rhinosaw]

Recently have noticed that when driving off , engine cold, the Abs light comes on and stays on after about 3 miles.
When engine warm light comes on sooner.
Have checked brake fluid and pads, all ok, car still brakes as normal.
Looking on the web looks like sometimes the sensor just needs a good clean. Is that possible or is it more likely to be a problem elsewhere?
Thanks

 

[Burnerman]

The ABS system isnt active until 3 mph or thereabouts, hence the delay.
Every wheel has its own sensor which maybe dirty with rust, brake debris or road dirt......they sense movement via reluctors on driveshafts, hubs or bearings, depending on the type. A garage with suitable diagnostics could identify which wheel is at fault which is a start.....its also worth checking the wiring in that area.
Id start with a driveshaft inspection first, often the reluctor cog splits or rusts away.
I do hope its not the ABS module!
John

 

[rhinosaw]

Thanks John
Sounds like the abs module is expensive?

 

[Burnerman]

Yes, the modules and pumps are expensive but often they can be rebuilt by the likes of BBA Reman or whatever.
I would recommend a full diagnostic if there aren't any obvious faults like torn wiring or reluctor rings snapping off on the front driveshafts. Sensors and reluctors are cheap enough though.
You don't need a main dealer, just a good, reliable independent garage with the appropriate diagnostic equipment.
John

 

[rhinosaw]

Is it worth cleaning the sensors first , that would seem the easiest thing for me to do myself .
Not heard of the reluctor rings, how do u get to them.
I think that the sensor screws into the wheel hub? Thanks again

 

[Burnerman]

The sensors are located on the hubs, usually with a one screw fixing......they are always tight, and always fragile!
Reluctors are like cog wheels, either on the end of the driveshafts or on the rear hubs. Some vehicles (French particularly) have a magnetic segment fixed into the wheel bearing itself.
The sensors need to sense the gap between the teeth of the reluctors, so its a good idea to clean them where you can.
John