Lights are stuck ON - Even with new LCM


Asked by Jul 13, 2015 at 03:11 PM about the 2003 Mercury Grand Marquis LSE

Question type: Maintenance & Repair

My automatic headlights are stuck on, regardless of the position of the headlight switch,
as long as the key is on.  (They go off when the key is off.)  I've replaced the LCM, and
the turn signal/wiper switch is new.  Should I replace the dash switch?  Where is the light
sensor?  With the red anti-theft light on top of the dash?  Will it need to be replaced, too?  
It's not a big deal, but it's kind of irritating.

5 Answers


Where did you get the LCM? If it is an after market unit such as Dorman that maybe the problem. The LCM units in these cars have extended warranty from Ford and your's will still be under warranty if the LCM is the problem. The Dorman units are pretty much junk and have been known to cause problems.


It's rebuilt; it's the second one. I replaced it as soon as I noticed the lights were stuck. I haven't pushed trying to get a new one from Ford since I replaced the first one years ago.


They are still under warranty. Something like 250,000 miles and 15 years.


263K+ here... I'm getting my money's worth out of this car!


LOL, You may be able to remove the LCM and resolder the bad solder joints (talking about an LCM that is the same as the original not an aftermarket unit). That is usually what happens to them. Google LCM repair.

Your Answer

Grand Marquis

Looking for a Used Grand Marquis in your area?

CarGurus has 1,242 nationwide Grand Marquis listings starting at $1,900.


Mercury Grand Marquis Experts

  • #1
    Tracy Hooks
  • #2
  • #3
View All

Related Models For Sale

Used Lincoln Town Car
21 Great Deals out of 1,447 listings starting at $1,850
Used Ford Crown Victoria
3 Great Deals out of 922 listings starting at $1,999
Used Chevrolet Impala
370 Great Deals out of 27,543 listings starting at $1,499
Used Ford F-150
2,535 Great Deals out of 221,934 listings starting at $1,222
Used Mercury Marauder
27 listings
Used Ford Mustang
294 Great Deals out of 38,678 listings starting at $1,995
Used Chevrolet Tahoe
646 Great Deals out of 37,897 listings starting at $695
Used Honda Accord
565 Great Deals out of 92,859 listings starting at $1,495
Used Cadillac DeVille
1,249 listings starting at $2,499
Used Chevrolet Silverado 1500
2,236 Great Deals out of 151,900 listings starting at $1,499

Used Cars For Sale

2011 Mercury Grand Marquis For Sale
15 listings starting at $6,934
2010 Mercury Grand Marquis For Sale
66 listings starting at $2,900
2009 Mercury Grand Marquis For Sale
5 Great Deals out of 81 listings starting at $3,400
2008 Mercury Grand Marquis For Sale
101 listings starting at $2,999
2007 Mercury Grand Marquis For Sale
7 Great Deals out of 98 listings starting at $1,900

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.