Terminator - He Hot Wired the Starter Not the Ignition!
When Reese steals the first car, he touches two wires together and the starter engages. He then TWISTS THESE TWO WIRES TOGETHER!! If he had really done that it would have been like holding the key all the way in the START position (as opposed to just IGN ON). Very big mistake for a James Cameron film.
You are correct....kind of. There are 3 wires needed to hot wire older cars. The first two complete the power circut, keeps the car running. the third wire will engage the starter but you cannot permanetly connect it to the other 2 or the starter will stay engaged and rip it (and the ring gear) to pieces.