03 caravan wont start. battery, relay, and starter are good. will crank but not start when jumping relay but wont do anything when using the key

Hello, Do you have a security light on or blinking, the key light on or blinking, or the alarm going off at times? This sounds like it could be an issue with the factory immobilizer not recognizing the key (issue with the anti-theft system or the key), or it could just be a bad ignition switch. You will want to test the ignition switch second, right after you try the spare key.