The vehicle in question is a 1997 F150 with a broken ignition switch. Inserting the key and turning it just spins. "Fortunately", the switch was left in the "on" position; the steering wheel is not locked and when the battery is connected, all the instrument panel lights come on just like they would when turning the key to the "on" position.
What I'd like to do is get the engine to turn over and hopefully start so the owner can take it to a professional to have the switch replaced without having to get it towed. I shorted across the starter solenoid and got the starter motor to run, but it's just spinning itself and not engaging the engine. Is there some sort of electronically-actuated clutch between the starter and engine that I also need to power? I could not find any other electrical connectors to the starter motor assembly.
The vehicle is not new enough to need a key fob to start, bit in any case, the original (mechanical) key is present and in the key slot.