I have a 2003 Grand Marguis as a second car. Recently, at night the headlights will just turn off by themselves. Usually I can play with the switch and they will eventually come back on. last night it happened twice. Once the switch play worked the second time it didn’t. I tried the bright lights but that didn’t work either. I pulled off of the freeway and played with the switch but to no avail. I then turned the car off and restarted it. Then the headlights worked. This usually happens about 10 to 15 minutes after I start driving the car at night. Once I get them back on they stay on. I’ve had the module checked and the repair man said it was OK. But it’s still happening. Any suggestions would be greatly appreciated.
If the car has DRL lights the trouble may be with it but if not then I would say the most likely suspect is the module. It has the most control of the low and high beams. Since shutting the car off and back on seemed to do the trick it sounds like something is getting reset in the module.
Pin 16 of the module should have power on it coming from the module to the light switch. It is a gray wire. If you are going to work on this yourself I suggest you purchase a service manual. It is a great investment for anyone working on there own car.
I too think that the LCM is at fault. It sounds like it has an intermittent internal fault. That is why the “repair man” didn’t discover that the module is bad. Replace it.
2003 and maybe 2004 has a known problem with substandard relays in that position. A new LCM is expensive, maybe as much as $600. The old one can be fixed. Find instructions here:
http://www.crownvic.net/ubbthreads/ubbthreads.php?ubb=showflat&Number=1437302#Post1437302
See if an electronics repair shop can fix it for much less than a new one from Ford if you can’t do it yourself.
If you own a 2003 and the LCM has not yet failed, installing relays and upgraded wires under the hood will prevent the failure and make your headlights brighter.