My '98 F150 is having problems starting. I don't want to waste a lot of time and money randomly replacing pieces of the system. When I turn the ignition I get one solid click (like a relay slamming shut). The battery is charged. When I crawled under the truck with the key in the ignition there was a loud humming coming from somewhere near the transmission. I was unable to isolate the location so I am assuming there is some electrical control device on top of the tranny, but it's only a guess. Eventually I turned the key one more time (immediately after calling the tow truck) and viola, it started. When I got it home I turned it off and IMMEDIATELY tried to start it. Same loud click, and nothing else. I have tried disengaging the security system but it has no effect. Anyone have any ideas on how to diagnose this one? It's my first Ford and I don't know the electrical system very well.

Thanks!

 

Check for corrosion of the battery cable going to the starter. There is a known problem with corrosion wicking up the cables. It is casued by different metals. The nut that was used to secure the cables to the starter are not of the same material and this causes corrision.

Regards

Jean Marc Chartier