Interior lights will not turn off when driving

CDAVIS188

MEMBER
1994 LINCOLN TOWN CAR
4.6L
V8
2WD
AUTOMATIC
154,000 MILES

I get in and start the car as normal, but the interior lights stay on. This creates an annoyance, especially at night. I've researched the problem and have found numerous posts about this, but my issue seems a bit different. The interior lights only stay on when the key is in the "on" or "acc" position, when I turn my car off and take the keys out the interior lights turn off as normal. I also have no door ajar lights on my dashboard. I tried the WD-40 method with the door latches to no avail, and checked the headlamp switch multiple times to make sure I didn't turn on the interior lights by accident. I finally resorted to taking out the fuse for them, but I also lost my power door locks and keyless entry system as a result of pulling the fuse.

It's also worth mentioning that the doors don't automatically lock when I put the car in gear, as they usually do. It worked fine a couple nights ago but when I drove to work the next morning I was presented with this whole issue.

Any help would be appreciated.

Regards,

Christopher

1 Reply

STEVE W.

MECHANIC
13,452 POSTS

The description sounds like you have a bad illuminated entry switch in one of the door locks or the wire which comes from the switch is grounded or the transistor that uses that signal to activate the lights inside the remote entry module has failed. This is the system that is supposed to illuminate the interior when you unlock the door. It is also why the locks do not work as it thinks the door is opening all the time. These are different than the door jamb switches that turn on the lights and the door ajar warning. To test and find the problem you will want to start at the module itself. That way you can determine if it's one of the switches or the module. The module is hidden up behind the dash on the passenger side. On it there will be three connectors. The one you are looking for has a Purple with light green stripe on pin 7. That is the input from the switch. There are two ways to test this issue. The better one would be to remove that connector, then de-pin that wire from the connector. Plug it back in and see if the problem is gone. If it is then the issue is in the wiring or one of the switches, if you still have it then it's the module.
The other way would be to cut the wire, if it shuts off the lights then you found it, if not you would repair the wire and replace the module.

Images (Click to make bigger)