Hi all,
I'm trying to test the functionality of a car ABS unit as far as it not putting up the ABS fault light and pre a professional refurb.
The fault code was 'open rear wheel speed sensor' but the actual fault is a failed 'signal reference' provision within the ABS ECU itself.
So the ABS ECU 'thinks' it's an external fault when it's actually internal.
So, for the purposes of the test, the assumption is that the 'signal reference' pins are all directly bonded together and to the ABS ECU ground, so that I could 'borrow' the 'signal reference' from one of the other wheel speed sensors or the ground itself and see if that clears the fault and extinguishes the ABS light. We tested this using a DMM on low ohms between ABS ECU ground and each of the 'signal reference pins'.
I didn't think to note the actual resistance of the 3 working pins, just that there was one that was o/c. (Doh).
When I measure at the actual wheel sensor connector with it disconnected, on the good side I read 5V across the pair, whereas on the bas side I read nothing, but do between the signal pin and chassis ground.
Cheers, T i m