abs light and sensors

[edd 0]

Right i know its an old topic but havent found a definitive solution as yet by the search.

 

ABS light comes on (usually) within a 30 seconds of making way. pump priming felt through the pedal okay on ignition etc. Sometimes when i move off and then brake slightly as the ABS light comes on I can feel the ABS activating through the front wheels (feels like front right but that could be just down to location of pump etc)

 

I have checked resistance of the sensors, they are showing

 

1.06 rear right.

1.05 rear left.

1.08 front right.

1.09front left.

 

i thought it should be a higher value but i dont believe all sensors have gone. so could be my ammeter. when this first started happening last year i just disconnected the ABS as im not a big fan of it anyway, alas now MOT time looms.

 

I suppose next step is a ecu read, but what are peoples feelings on the sensor resistances.

[dr_mat 0]

Well given that they're all the same I doubt you have an electrical fault in one of your sensors. That doesn't mean you don't have a mechanical or magnetic fault.

Read the ECU, it'll probably say something like "implausible signal" for one or more sensors.

 

My guess would be that your meter was auto-ranging in the kOhm range, so those values are ~1000 Ohm, which is perfectly reasonable.

[Supercharged 2]

Yeah you need to get it on VAGCOM - maybe the pedal position sensor?

[Neil VR6 0]

My ABS was VAGCOM'd yesterday and it had a fault on the power supply and a fault in the actual valve control unit (over £1600 from VAG). Might have to go to the scrappie methinks.

[Louis 0]

I have had this problem since buying the car, at Stealth at last year's service, the ecu read a problem with a valve on the pump. On the grounds that my ABS still works fine I decided not to pay for a whole new pump.

 

I'm not so sure I believe the reading anyway, because if the car has been warmed up and the ignition turned off and then on again, the warning light turns off. Also, when the indicator is on, the light flashes slightly with the indicator. Due to this, I kind of think it might be an earthing problem. Anyone had this? If it is I'll gladly sort out the earthing as the light does my head in.

[edd 0]

as a follow up,

 

having tested all the sensors and finding correct resistance readings i had the ECU read which was throwing up a front right sensor error. replaced both but frustratingly found that the problem was continuing. i then discovered that the abs light would come on when the wheels were turned through full locks (i.e. stationary). upon rechecking the new sensor resistances from the strutt i was getting a continuity error when the light was staying on immediately after start up, turns out the cable from the sensor to the strutt had a break in but was only causing a break for a fraction of a second but enough to cut the abs operation and log an error. new cable all sorted.