Hi Phil,

I am just wondering if you have ever considered that the starter might have a problem internally.

Very possible -- if the symptoms would include the starter continues to turn after the key is taken out of the ignition switch.

I have read that some of these cars may have had a wire that runs down to solenoid terminals, somewhere near the brake booster/firewall, but have never investigated it to be fact.

Some of these cars? By that, do you mean certain 1986 240's? Or are you thinking of the terminal 16 ballast bypass for k-jet cars?

In the '86, the starter wiring is just one loop shy of being straightforward. That "loop" is the remote starter test connection, up above the motor on the firewall. The solenoid wire at the solenoid is blue/yel. It runs from the solenoid, through the infamous engine harness, through the infamous gray plug on the firewall, to the cabin harness and winds up at a two-pin plug just northwest of the shifter, under the carpet.

That two-pin plug is where Volvo decides to wire it right to the blue wire if you have a manual, or interrupt it with the neutral safety switch on the automatic. Now blue, two wires leave, one to loop it back out to the firewall for a starter test terminal, and the other to the momentary contact at key switch position III.

This plug makes a good spot to test the "bad ignition switch" theory one poster offered. If the OP had mentioned automatic, simply putting the shifter in gear would have stopped the starter, had it been a broken spring in the ignition switch. If manual, of course, the jumper plug would need to be pulled to do this check.

What I believe happens in the "starter won't shut off" situations with the original harness is the red alternator exciter wire shorts to the blue/yellow solenoid wire. Once you have the motor running, the exciter current developed through the small exciter diode trio in the alternator keeps the solenoid engaged, until you take the key back to KP-0, removing ignition coil voltage, stopping the motor, and of course, stopping the alternator.

For the OP - a good history of this is found here: http://www.davebarton.com/volvoharnesses.html

Phil, I know you've been around long enough to have seen this before.
--
Art Benstein near Baltimore

A man's knowledge can never outweigh his experience.