WTB: ABS Sensor

[mattnz]

ECU says that my FL ABS sensor has packed in. Has anyone got a spare one? :)

[VR4WGN]

adress you clown?? why dont you just ask me to send you 1? i have some here lol......

[Davezj]

ECU says that my FL ABS sensor has packed in. Has anyone got a spare one? :)

i don't want to tread on toes here but,
are you sure it is the sensor and not the Tone wheel (if that is the correct name for it) the toothed wheel that the sensor reads the speed signal from. i have heard of lots more of those breaking (loosing teeth) than the actual sensor, and i think it gives the same error code.

have a look atthe back of the hub area and ensure you have not lost a tooth off the wheel. if you have lost a tooth it is either raplace the tone wheel or easier the entier drive shaft.

[mattnz]

Will do, it has been like this since being converted to manual though, so that is when the sensor may have been nicked.

Also, I'm pretty sure that the error pops up instantly on ECU reset, and it would take a bit of movement for it to sense a tooth missing right?

[Davezj]

Also, I'm pretty sure that the error pops up instantly on ECU reset, and it would take a bit of movement for it to sense a tooth missing right?

yes, that sound about right. i think your logic is sound.

you could always test that theory by un plugging one of the other ABS sensor to see if an error code is flagged up for that one as well.

the other thing you can do is measure the resistance of the ABS sensor with a multimeter it should be a few 10's of ohms. the actual value i can't remember off hand but as long as it is not open circuit (massive ohms, OL), or zero ohms (1 ohm or less), then it should be OK. again you might want to compare the value with one of the other ones that you know works.

[mattnz]

Just checked with a reset, and ASC code 12 (FL wheel speed sensor), AYC code 22 (also FL wheel speed sensor) came on after a small drive, which I suppose could be down to propagation.

How does one go about measuring these resistances? I haven't had much experience with the braking systems.

[Davezj]

ABS sensor only has 2 pins in the connector, located behind the front wheel arch liner at the top, just disconnect the connector and put the meter leads across the connector terminals, it doesn't matter which way round the meter leads connects to the sensor as the sensor is just a coil of wire effectively.
As each tooth of the tone wheel passes the sensor it changes the magnetic field within the coil and creates a very small electrical charge this registered as a voltage (very small, only a few mV), this is what is measured by the ECU as a series of pulses as the wheels turn.
If you change the resistance of the coil via a fault or a dodgy connection or change the distance from sensor to tone wheel then the voltage generated by the sensor will change massively in comparison to the size of the original pulse signal which is very small to start with.

[Kenneth]

One thing to note (don't know if it applies in this case) is that if you un-plug a sensor, start the car and move it then you will get a sensor error code. You then wont get rid of it again until you move the car with the sensor plugged back in. I spent ages playing around because the error code wouldn't go away, only to find that once I started driving it cleared.

[Davezj]

oh good bit of info there kenneth, i would not have thought that was the case, but it is good to knoe that it has been tested and it is fact.

nice one.

[mattnz]

Buuump :)