Questions and Answers

Mercury Grand Marquis Interior Lighting Q. Vincent, I have a 1999 Mercury Grand Marquis. It has a Headlight switch with a timer so the headlights stay on for a while after you get out at night. On the same switch, by pushing in, you can turn on the dome/courtesy lights. The system is designed so that the interior light stay on for a few minutes after the door is closed and then gradually fade out to off.

The problem is that after a little while the lights mysteriously come back on and then a few seconds or minutes later they fade to off again. This cycle will continue all night. There does not seem to be any pattern to the on/off cycle.

Of course, it should not be coming back on period without opening the door. I look out my window in the middle of the night and the lights come on and fade off. Is this a relay problem or what? If so, where would I locate the relay.

Thanks,
Larry

A. There are two main parts to this system, the head light switch and the Lighting Control Module (LCM). Gee, what ever happened to keeping things simple? Well, anyway, I think the problem is with the LCM. I don't believe the head light switch would cause the symptoms you describe.

Unfortunately there is no test procedure, that I know of, for it except exchanging with a known good unit.