This has only happened to me twice separated by 3 or 4 months, but when I went to go start my '99 Ranger XLT, power to the entire vehicle was rapidly switching on and off, and I could hear a "clicking" that sounded like it was coming from inside the dash. Oddly, turning my headlights on and off stopped this behavior and I was able to operate it normally. My first thought was the key switch, but if I'm not mistaken, the headlights aren't routed through the key switch (besides the fact that I don't see how turning the headlights on and off could possibly "cure" an electrical problem anyway). Has anyone else ever experienced this kind of oddity in a Ranger or any other vehicle?

 

Clean your battery terminals.
And I don't mean just washing them off with a hose.Unbolt them and scrape them off.

 

That was the first thing I did (I guess I should have mentioned that). Both terminals are clean inside and out.

 

Then remove and clean the other ends of the cables.
Also inspect the cable terminals for corrosion.Some tend to rot off just inside the insulation.