'96 Grand Am w/theft system, sometimes refuses to start

Our Grand Am runs well when it decides to start! But occasionally when the key is turned all the way on, the starter may take a few minutes to engage, or not at all. Usually it just starts right up, but not every time, so it is not reliable. The key lock cylinder has been replaced.

This problem may not be related to the anti-theft system, if this car even has one. Do you have a “security” light in the dash flashing at you when the car fails to start?

does the theft system have a starter kill? It’s common for connections in those to get loose and kill the starter even when they’re not supposed to.

Yes, it does.

How do I find out?

Perhaps this link will help.

One thing to bear in mind with these “resistive chip” designs is that the system reads the key’s chip resistance through the key itself. If the key is badly eroded or contaminated, the system may not be recognising the proper resistance and be resisting allowing the engine to start. GM has had a chronic problem with this.

Note that it might also be a corroded contact set in the starter relay or even in the starter assembly itself. When you turn the key to “on”, a relay closes to enable the starter solenoid to move the starter motor gear into engagement with the flywheel ring gear and to close contacts to enable full battery power directly to the starter motor. The latter contacts, the ones in the solenoid, arc with every engagement, and they can fry over time and become intermittant.