Thanks for the reply, I should have paid more attention to this thread. I thought the thread became inactive, but it was still going.

"As it is a 1989 240, you have the OBD diagnostic test function. If your battery has kept a charge so the fuel injection and ignition still contain fault codes, why not try the OBD function"

It reads 1-1-1. I thought there must have been a problem with the ICU, as at the beginning of this adventure, there was no OBD reading. Turns out, there were only dirty contacts on the OBD unit.


"What did you do about the slow coolant leak?"

I replaced the water pump, and upper and lower radiator hoses. Fun tangential project- I also replaced the radiator, as I tightened the hose clamp too tight, and the (maybe original) plastic connector on the radiator shattered. I was fortunate enough to find all the pieces.

"As our Uncle Art states, we're trying to help you and want your 1989 Volvo 240 to keep on carrying on. Though we cannot use our collective remote-control telekinesis mind power to pick up and use that multimeter to help you."
Thanks, and I'll try not to appear ungrateful.


"
If pressed, and you need in-person help, let me know here or by PM. I also reside in the fetid notion known as St. Louis, Misery. " Thanks.



And your 1989 240 has a manual transmission? Yes, it does. The manual transmission one is the one with the problem. My stay-at-home parts car, another 1989 240, has an automatic transmission.



Do you use a Volvo literate mechanic? - Not yet.