You don't give year and model.....
There are these systems....PassKey I, II, and III.....I and II use resistor chips.....III has a transponder built into the head of the key and has "PK3" or a circular symbol stamped on the shaft of the key.....the other system is PassLock....this uses a blank key....
Still, another system is the immobilizer system, which needs no key to start....