Headlight gremlins...

[David Dousette]

It was 35 degrees this morning (the coldest morning since I have owned the truck), and as I was letting the Trac warm up in the driveway before work I noticed that the headlights were blinking at me. The switch was turned off, but both the interior dash lights and the headlights themselves were blinking on and off in a regular pattern approximately every 5 to 6 seconds.



I first thought it has to be the headlight switch itself, but it did the same thing whether the switch is on or off. The pattern just changes to on/off/on/off instead of off/on/off/on. This is a 2003 XLT with no automatic headlight controls.



I had the thermostat set fully to heat and the vent control set to the defrost-and-foot setting when this was occuring. It continued doing this as I drove it to work until I changed the vent control to the regular face-and-foot setting and lowered the temperature. I then moved the vent control back to the defrost-and-foot setting and the problem did not reoccur. Time for testing was then over since work is only a few miles from home.



Do I maybe have a relay that is cycling itself on and off? Has anyone else seen this problem before? It is one thing for the truck to do this in the driveway while warming up or on my morning commute, but it would be quite another to have it do this on some country road at night.

 

[Jerry Gerner 2]

If it was early morning and still somewhat dark out hten the autodim on the rearview mirror will want to turn the lights on regardless if the switch is turned on/ off. Mine does this all the time. It's the daytime running light auto dimmer on the mirror, atleast that's what's causes it on mine.

 

[David Dousette]

Huh... that's what that switch on the mirror is for, then. I made sure it was all the way in the "off" position this morning and it didn't act up, so I guess that was the culprit in my case, too. Thanks!