Vehicle ABS ECU circuit question please.
From
T i m@21:1/5 to
All on Sun Aug 27 11:30:27 2023
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
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