For some reason I got in my truck yesterday night (01 King Ranch 4X4) and I leave the lights so they automatically come on if its dark outside and when I cranked it up the lights came on then went off...then on the off.....then after turning truck off with key out of ignition the lights did the same thing....when I got in it this morning same thing just kept clicking and going on and off, do these sensors get dirty and need some air sprayed on them.....does anyone know where the fuse it for the sensor.....what do you think I need to do....hope someone can help with this problem.....thanks

 

Just out of curiosity, were you parked in an enclosed space where the lights may have fooled the sensor into thinking it was too bright and turned them back off? I've seen that happen, but not since an '88 Lincoln Town Car. (sensor was on the mirror)

Another possibility is a large voltage drop due to a battery on its last legs. The voltage drop at the battery could cause the battery saver relay to kick on. Then, as soon as the lights go out, the voltage comes back up high enough that the battery saver relay clicks back on, and when the lights come back on, it repeats the cycle.

Those are my best guesses anyways.

And FYI, the sensor is in the top, front, center part of the dash beneath the little grille.

-Joe

 

The truck wasn't parked under anything and it did it lastnight also....What I've read on here its looking like a bad sensor...??

I don't understand what you mean about the battery.....is this the battery under the hood or is it some kind of backup battery in the cab.....???

 

I have auto lamps and they have a buffer built into them so it doesn't keep turning on and off in marginal light.

The sensor is in the center of the dash under the oval piece on the passenger side. there are 3 or 4 small slots for the light to get to it. put something over them and see if it still does it.

 

He's talking the main (and probably only) battery in your truck. If the battery is near its end of life it won't be able to support the load of the headlights without rapidly dropping its output voltage, thus causing the battery saver to drop the headlight circuit, trying to "save" the battery so you can start the engine.