When you open and close your car door, a contact switch is either opened or closed causing the light to come on or off. The switch is usually located on the door frame some where and it is adjusted so that it has just enough physical contact with the door to operate freely. If you lights and "door ajar light come on erratically while driving, I would think that the switch is lose or out of adjustment.
Because there is a light inside of the warmer, and you see the reflection from the light.
flicker
A flicker, a beam, a ray.
Metal Halide can flicker when warming up cause it is starting to get hot inside. Or Metal Halide can flicker when it is about to burn out. Sometimes they even cycle.
only a light flicker or two.
The answer is flick or flicker! XD LOL
Possible alternator problem
Flicker.
It's common on most Ford's for the light switch to burn out on most models. The newer vehicles have been fixed but that's where you could start.
Sounds like the regulator in the alternator is going out.
Faulty wiring.
the oil sender unit need to be replace.