My 1998 F150 Headlights lenses got cloudy as all these plastic lenses do over the years. I replaced them with new ones and what a difference it makes. The whole job took twenty minutes. No big deal at all. Pull the retaining clips, unplug the electric, swap the light and reinstall. All done right? Well no. Now the lights don't shut off by the automatic sensor like they used to. The sensor will turn the lights on. The sensor is in the dashboard upper surface it controls the lights by the amount of light out side. I can't imagine changing the bulbs has any thing to do with it but the automatic sensor is not working correctly now. Could the two be related or did I just notice the problem because I was working on the lights? If it's dark the lights come on but daylight won't shut them off.

 

Could be the sensor, or the relay could be sticking on. It's probably located in the GEM module.

 

I hear the relay click on automatically but I don't know where it is. Where and what is the GEM module? I can keep the lights off by turning them off at the light switch and then back on to automatic. They will stay off untill the outside light diminishes but once they turn on they will not shut off.

 

It should be behind the fuse panel. It controls about everything electric in the truck such as power windows, delay wipers, etc.
Look for any signs of rust or a possible small windshield leak. This can cause weird things to occur. Sounds like it may be the sensor though if they go off when you turn the switch to off.

 

It appears that my truck has Automatic Repair as well as Automatic Headlights. The problem has corrected itself somehow. It may very well come back but for now it's working again. It probably is the sensor or relay but I don't fix things that are not broken. Time will tell. Thanks for your Help.

 

No problem