ABS

[happypug]

Hi all.    Can anyone tell me what it means to have the abs light on. It came on Thursday, brakes work fine. Is it a sensor or the abs pump?  Am taking it Monday to plug in OBD at my mates garage.
 Cheers for any info. 

[welshpug]

it means there is a fault with the abs system somewhere, could be anything.

[daddyfixit]

its faulty and its switched itself off; you can lock wheels up when braking hard.

[pug306driver]

a good starting point would be to check each individual sensor first.....disconnect the sensor lead and check for a signal from the sensor lead via a digital multimeter....rotate wheel as fast as you can by hand and see an output.........low voltage setting.

I did this test on ours some time ago ( about a year ago now, a resistance check was done for the sensor at the same time ) and saved the data in the manual, which is of course at home!

a NO signal from an individual sensor means a problem with that sensor........

the sensor is basically a coil wrapped around a magnet, whos magnetic field is influenced by the castleations on the abs ring on the wheel......the "vee" strip sticking out of the sensor pointing towards the abs ring is magnetic........no idea what the air gap is........but its fairly close.

our front abs rings where badly corroded, so I carefully removed the corrosion, just in case some "magnetic field fringing" was taking place and upsetting the system.

a new abs bulb ( the bastard who sold the car had taken that and other bulbs out ) and work mentioned above sorted the abs light.

system works cos when the front of the car was up in the air and one wheel rotated in gear, the light came on, which cleared when taken for a quick spin around the block. we have not been in a position to test the system in real life yet and not locked any wheels.....so heres praying!

[happypug]

Hi all.    Can anyone tell me what it means to have the abs light on. It came on Thursday, brakes work fine. Is it a sensor or the abs pump?  Am taking it Monday to plug in OBD at my mates garage.
 Cheers for any info. 

 Hi all.    An update to original post.  My mates OBD says it`s the L/hand front abs sensor at fault.  It will be replaced next week when he can do it.   Thanks all for advice.

[C2K]

Check that the reluctor ring it's supposed to read from is still on the drive shaft...

[Niall]

Check that the reluctor ring it's supposed to read from is still on the drive shaft...

This. Quite a common fault for them to come off all together! It looks like a toothed ring on the drive shaft