Volvo 960 won't crank

My wife has a 1995 Volvo 960 with 110,000 miles. Now and then, the car will not crank. The lights are all on, the dashboard lights are up. You turn the key, and nothing. No cranking, no sounds at all. My wife has fiddled with the Shiftblock overdrive button under the automatic transmission shifter, and she says this sometimes frees up the car so it can crank. We can fiddle with this and other things for a while, and then suddenly the car will crank and start. We’ve noticed it happening if we drive a short distance, turn the engine off, and try to start it about five minutes later. Now, with the cold weather, it seems to be frozen. It’s as if the Volvo thinks it’s not in gear and then won’t let it crank.

Any ideas?

I sounds like a loose or failiing gear position sensor, which needs to sense that the car is in park or neutral before the engine management system will allow the engine to crank.

The part is a little over $100. Installation may be about as much.