Alright guys, the original motorcraft battery in my 2000 F-150 went kuput yesterday. Anyway. I had to get a jump to get it to a local parts store and once it was jumped off, by a jump box, the starter just kept running. I turned off the switch and it continued to try and start the vehicle. I popped the hood to disconnect the battery and just as I went to pull off the neg cable it stopped. Today, it has done it 2x's also and the only way to get it to stop was to disconnect the battery. Wait a few minutes and then she'll crank right up like the gods invented her to. So, what could this issue be? Is it a short in the starter solenoid on the starter? Or could it be a short on the underhood solenoid? Any insight on this will be helpful as I'm trying to cut down on my diagnosis time.

 

Three possibilities, each with a different test:

1) Ignition switch sticking internally in the START position. Try pulling the wire from the coil terminal of the starter relay to isolate. If the starter continues to run with the wire pulled, the switch is not the problem.

2) Starter relay shorting internally. Pull the cable to the starter motor while running. Easier said than done. It's a cheap part, I'd probably swap it instead.

3) Bendix in starter hanging up. Try hitting it with a rubber mallet or a broomstick to see if it frees up and disengages. If it does, new starter time.

Steve

 

Odds are high that it's the starter relay. You don't need to pull the battery cable off if it happens again before you can replace it, just carry with you a large screwdriver, and when it happens, rap on the relay once with the handle. You're not trying to break it, just give it a good rap, and it will stop.