Why do the headlights on your 1998 ford explorer sport go off and on intermittently?

Answer 1

This answer will be generic in nature as it applies to most modern vehicle headlight systems which usually use a circuit breaker instead of a fuse to protect the headlight electrical circuit(s). The purpose of a fuse or circuit braker is to turn off the electrical current to the wiring circuit it is installed to protect. For several years most of the major auto manufacturers [Ford is one] have used "self-resetting" circuit breakers in the headlight circuits. A self-resetting circuit is one which, after a very short cool-down period, following a trip-out, recloses to allow the headlights to come back on. A fuse or circuit blows or trips by design, and is a safety factor in protecting the wires of that circuit from overheating and/or melting or causing a fire due to a short circuit to ground, or an overload condition. The purpose of a self-resetting circuit breaker in a headlight circuit is so that IF a short circuit causes a trip-out on a dark road at night, the lights can come back on for a short time to allow the vehicle driver to be able to see enough to stay on the roadway long enough to slow down and stop. Any time a fuse blows, or a breaker trips, it is caused by excess electrical current [measured in Amps] flowing through the circuit. Current in excess of that for which the conductor [wire] was designed, causes a wire to get hot, and if the current is not stopped, the wire can overheat enough to destroy itself, damage adjacent wires, and in the worst case scenario, start a fire which can be very dangerous. From the symptoms you describe, you have a short circuit somewhere in your headlight circuit, which must be corrected as soon a possible. Due to the hazards of night driving, it is critical that you should not drive this vehicle at night until the short circuit, or overload, has been corrected by a qualified automotive electrical technician or mechanic.