Mk2 Mondeo Brake Issues

[Kitchster_uk]

Quick question, I have recently picked up a late model 2000X Mondeo Zetec-S for my gf to drive over the winter. It's a proper cheapy at £500 with tax and test and 102k on the clock. Drives well but there seems to be a brake issue. At sub-15mph, the ABS sounds like it's kicking in. Now, the ABS light comes on for 3 secs when it's started and goes off as it should, but could it still be a sensor? Or is an ECU fault more likely?

Cheers

 

[daveydave]

Sensor is most probable at that age and with the weather we've had.

 

[Phil W]

Could be a sensor, or a cracked/broken ABS ring.

 

[Dogbreath]

Could be a sensor, or a cracked/broken ABS ring.

Almost certainly one of these. Real pump/ECU faults (as opposed to the garage blaming them because they don't have a clue) are pretty rare.

 

[Phil W]

Almost certainly one of these. Real pump/ECU faults (as opposed to the garage blaming them because they don't have a clue) are pretty rare.

Also indicated differently, by ABS light being on permanently.

 

[Kitchster_uk]

It's weird, no noise above 15mph, none in reverse and no ABS light on. If the light didn't come on at all I would suspect the bulb had been removed but this isn't the case.

I'll have the wheel off and have look when I get chance, cheers for the suggestions!

 

[Dogbreath]

It's weird, no noise above 15mph, none in reverse and no ABS light on.

It's pretty much standard behaviour for a sensor/ABS ring fault. The sensors are inductive, so the output amplitude (and obviously frequency) increases with speed. If you have a duff sensor or cracked ABS ring, then the sensor can still provide enough output at higher speeds to operate correctly, but as you slow down the voltage will reduce below the threshold that the ABS controller can use, and it simply appears to the controller as though the wheel has stopped turning.