I'm having issues with my auto headlamp setting not working lately. Sometimes it will come on when I first start up my 2003 XKR in the garage but goes out in daylight and doesn't come back on at night.

Also, I've noticed that the instrument panel dimmer dial works fine when the headlights switch is set at auto (when car is in the garage before they go out) but when the headlight switch is set to the "on" position the dimmer dial only dims the center console lights and not the main instrument panel (speedometer, etc).

Anyone have any thoughts on this?

Also, does anyone know for certain where the sensor for the auto headlamp is on the mirror. Looking at the back of the mirror I see three sensors. One is on back of the mirror housing on the drivers side, this can be manually touched/covered from inside the car. The other two are visible looking through the windshield and are located within the part of the mirror housing that is attached to the windshield so you can't see/touch them from inside the car. I know one of these three is for the wiper auto setting, and one is for the auto headlamp setting but I don't know which is which. I do know the small dome on the dashboard which some mistake for the headlamp switch relates to the cars air conditioning so that isn't isn't being considered. But if I knew exactly which one is for the auto headlamp it might help me do some testing of my issues.

 

I had an issue with a solder joint on the indicator stalk that gave me intermittent or non-working "auto on" headlights. Just a thought. Try jiggling the stalk around in auto.

 

I had a non functioning AUTO headlights issue and it was the mirror. When in the garage, I slightly moved the mirror and the lights came on. I replaced the mirror from a wreck. Problem fixed!

 

Tried jiggling the stalk and it didn't do anything.

We went on a longer trip a couple days ago returning at night. The auto switch worked and the headlights came on and dimmer was working both in auto mode and headlamp on mode. After about 1/2 hour driving with switch in auto position the headlights turned off in a dark area. Switched them back on by turning to the headlamp on position and from there the dimmer no longer worked.

So this appears to be some bat wiring, or a bad part, that relates to both the headlight auto on position and the wiring for the dimmer dial.

Any thoughts on what I can try to diagnose it?

 

Try moving the mirror itself while in AUTO. The sensor on the mirror's back is for auto dimming of the mirror. The 2 on the mount are sensors for available light and moisture detection for auto wiper function. You could tape over one sensor at a time to determine. Spray water on the glass with the wiper stalk in auto and key on. Switch the tape to the other sensor if the wipers don't activate. Again, my issue was the mirror. Rather than inspect and trace each wire, I replaced it.

 

Just a thought but many years ago, decades really, a set of driving lights I had installed on my Mustang would cause the headlight relay to overheat and shut off my headlights. Cool down and my lights would work fine until the next time in tried to use the driving lights and the process would repeat.

In my case (not applicable for you) I installed a separate relay and used a different power source not directly linked to the headlight circuit.