Hi, need same help with my brake system on my 1975 HJ ute. when I went to get the rego done on my ute the guys picked a couple of faults, one being that the LPG tank needed to be enclosed when put in the load area of a ute, thats done. Then there was no brake warning light on dash, I found that the power line going to sensor had come off, put it back on & light is now coming on & going out when engine starts, great all looking good for rego. Then went back to NRMA service center to have the headers & exhaust replaced. Started it up the day after I got it back from the NRMA & brake warning light is now staying on, did not noticed if it was on during drive home, checked master cylinder & found front reservoir was just about empty, topped it up but light still staying on. Was told to pull sensor out & pump brake pedal then put sensor back in, this should reset the sensor put light is still on. don't now why front reservoir was so low can not find any leaks & reservoir seams to be staying full now. dose anyone now a way of testing the sensor or how to check the proportioning valve that the sensor go's into. have tried to find a new sensor from rare spares, Holden & a couple of wreckers but nobody has them.
Thanks for any help

Dean