I genuinely thought I'd never get the ABS light to go out, and, as it was preventing me getting an MOT certificate, I was genuinely thinking about scrapping the car. One last try...
Got the meter out and tested resistance on all the sensors again. About 1.1 kOhms on the front two - open-circuit (infinite resistance) on the rear two. How could both have failed, simultaneously, while the car was just sitting on the driveway??
Well they had. One of them I cured by chopping into the cable near the sensor entry ppoint, and soldering in a new length of cable (I used 50 Ohm co-axial from a spare TV lead!). All wrapped up with good insulting tape, finished off with self-amalgamating rubber tape to keep the water and grime out.
The final one, of course, was more difficult. Ended up removing the caliper, disk and bearing to allow me to (gently as possible) drive the sensor out with a wooden drift. Even as the cable entered the sensor unit, clearly open-circuit. In desparation, got the hacksaw out and renoved the sensor can itself from its solid rubber mounting block. Underneath all that rubber, found the actual terminals. On with the meter probes...Wow! 1.3 kOhms! Fire up the soldering iron again...!
Having attached more TV cable (it's co-ax to suppress RF interference to the radio, I think, so you could use plain twin-core if you want) , I wrapped it all well in more self-amalg, and gently tapped it back into the hub backplate. It's a matter of visual judgement getting the airgap between the sensor and the toothed wheel right, after putting the hub back on (and torquing the hell out of it...210 lb/ft!) The unit is an interference fit even when it's clean and shiny, so the absence of the rubber mounting block with its single 10mm bolt doesn't worry me.
And "bugger me backwards with a broadsword", the infernal little ABS light came on, blinked for a couple of seconds, and went out! And stayed out while driving, too!
Shiny new MOT certificate and (touch wood) a few more years on the road for the Scarabe Green Lady.
Hope this helps - desparation can pay off in the end!
