I used Bruce Young's tests below to confirm that my no start problem does indeed appear to be the hall switch. The receptacle for the harness connection, that extends outside the distributor, had broken a long time ago. I had glued it to the distributor, but a mechanic apparently broke this repair, to the point that it was dangling loose, and broke the connections through to the switch itself, inside.

Replacement distributors are proving hard to find, and I think the sensor replacement is fairly difficult (not to mention that the hall sensor price is probably quite steep). I was going to try to see if I can repair this connection from the external receptacle through to the sensor. Can anyone tell me if it's possible to apply voltaget to two of the three pins, then run a feeler guage through the hall switch, and read this on/off voltage on the 3rd pin?

Which wire colour gets the positive voltage?

Can you apply +12V here, or does it need to be a lower voltage, or through a series resistor?

Which wire gets ground? If I know 2 of them, then of course, the 3rd is the output voltage.


Here's Bruce's tests I ran; passed #1, failed #2

Here are a couple of tests I save in my "Canned Responses". You already did #1, with the B-C jumper substituting for the Hall Switch and showing the ICU switching to be OK. Try Test #2 to see what it tells you.

1 - ICU Switching Test
1) Pull coil wire, attach/adapt to spare (grounded) sparkplug.
2) Rmove the ICU 3-wire plug from distributor body.
3) Insert a jumper from plug socket B (Yellow wire) to socket C (Black wire). When jumper is REMOVED (step #4) the plug should spark, and the fuel pumps should run briefly.
e4) Key ON. Check for spark and pumps as jumper is removed.
•) If Spark & Pumps occur, suspect Hall Switch or wiring.
•) If no spark, suspect ICU or wiring.

2- Hall Switch Test
1) Key OFF. (Coil wire and spare plug still set up as in Step 1 above).
2) Remove distributor cap.
3) Rotate engine till a Vane "window" is centered in front of the Hall Switch.
4) Turn Key ON.
5) Pass a feeler gauge blade (or similar) through the Hall Switch (simulating the Vane).
•) If the Hall Switch and ICU are OK, you should get a spark and fuel pumps should run for a second.
•) If no spark but ICU test was OK, that points to the Hall Switch/socket.


Thanks,
--
David Armstrong - '86 240(350k km?), '93 940T(270k km), '89 240(parts source for others) near Toronto