Here's how I diagnosed mine. Turn the engine into the run position but do not start the car. Click the OD button, your arrow should turn on and off and you should hear a very quiet click from behind the ashtray. Next, stick your head under the car as far as you can while still holding the shifter. You should hear a click from underneath the car. I could hear no click so I got out a 6' piece of insulated wire, shoved one end down into the positive battery post, then crawled under the car. I unhooked the little connector that is in line with the wire going to the solenoid and hooked up my 12 volts directly to the solenoid. I heard a click so I then knew the problem was in the wiring or solenoid. Re-soldered solenoid, problem solved.

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Bob W.
15 Volvos ('58-'91)
445-544-122-240-740