I have a 99 Expedition and it just started engaging the starter while its running. I replaced the starter solenoid and a flasher relay. Took the starter switch off and put it back on. I still hear noise from the starter solenoid like a circuit spazzing out. And with the key on the starter kicks in quick and slaps the flywheel after about 7 minutes. Do I need a new switch? Very strange..

 

Do you know if the windshield on your vehicle ever leaked ? If there is a lot of rust over the area of the CJB (Central Junction Box) interior fuse panel corrosion there could possibly explain what might be happening. Problem from corrosion in that area caused quite a few unexplained things.