Hi Phil,

The 89 manual shows the service port where Dave says in the engine bay harness
high up the drivers side fender about half way from the battery to the firewall.
It is a short wire with a single plastic connector shell for a 1/4" spade.
I have fuzzy recollection that one of my Volvo's had that port breakout on the
passenger side also up high. (look on the passenger side too)

You can try plan B as follows: Put the key in run position and tranny in Park.
Start by shorting the two fat solenoid lugs with a big screwdriver.
I had to do this with two intermit no start starter motors in my 740.
They would work fine then suddenly be dead as a mackeral, then spin the starter
with the screwdriver and back in business for months or minutes depending on
Murphy's mood. There's an AWD post now that someone found this problem was due to a binding solenoid, and I'm hoping to hear more details from him.
I still have one of the funky starters so I'll take a look at the solenoid when
I get some time.

You did clean ALL the battery terminals? Yes?

Good luck, Bill