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Ford Crown Victoria/Mercury Grand Marquis Electrical/Lighting



  • euphoniumeuphonium Great Northwest, West of the Cascades.Posts: 3,321
    I'm with you on disconnecting the Negative terminal, but I hesitate touching the Negative cable to the Positive post on the battery. Would this "touching" cause an unwanted spark and maybe blow the dio plate in the Alternator?
  • bigrich52bigrich52 Posts: 3
    I learned this trick today at the auto shop.. Having an issue with ac control box.. Mechanic removed the wire and did just what i had stated.. nothing ill came of this except i had to reset my clock.
  • selma2selma2 Posts: 2
    hello,i havent experienced the headlight problem yet,,,but i dont drive it much ,only 43,000......what is happening with my car,is the fuel pump went ot at 32,000....then it went out again at 38,000....i am still waiting for the shoe to drop on the 3rd fuel pump with only 43,000,,,,the pump is inside the fuel tank,,,a design only a moron would it is quite a job,around 600.a pop,,,my car is a 2003 marquis far as the headlights are concerned,,,,ford has always had weird electrical problems with their cars as far back as the early 1950s....the lincolns and the edsel were nightmares......selma2
  • I am having the same problem. What did you have to do to fix yours?
  • I have this exact same problem my friend with my 2005 Mercury Grand Marquis GS. the lights come on when they want to and i will hear it click and come on when they finally do. Also my air does the exact same thing as yours only blows out of the top and im getting frustrated. Can you please help me and tell me what you did and replaced to get rid of these problems. Thanks
  • raszmanraszman Posts: 4
    mine was due to the right front fender being replaced during paint job and they failed to tighten a ground wire that attaches to the fender inside.
  • Problem started with no left turn signals; found blown fuse (15A) in position #16; replaced fuse and turned on left signal that immediately flew new fuse; also noticed no mirror compass, night dimming or interior temp controls; put 2nd new fuse in but still no turn sigs and hazards, fuse did not blow this time; started engine but could not shift from PARK; thought about it and removed the 2nd fuse (still good) from position #16 and it shifted right out of PARK; assume a short in some switch, probably the turn signal switch; anyone had this issue?
  • When we bought our 2000 Grand Marquis in 2000 (it had 6,000 miles on it), the salesman said that the previous owners said that the car was "possessed". Well, we didn't think much of at the time, but now realize what they were talking about. We've had the car 12 years.
    Last Fall, (Oct. 2011) we were coming back from Louisville, pulling a boat trailer at 8:00. All of a sudden, we lost all lights on a rural highway. We pulled off, and I thought the problem was the trailer lights, which I unplugged. The lights worked, and we got home.
    Two months ago (Oct. 2012), we were on a rural road (no trailer), and they went out again. I had to use emergency flashers to get home. I called the dealer, and he said they replace the lighting module ($512) on the Marquis, all the time. I got on this forum and verified that was the problem.
    I got the dealer to change the module (it took two visits, as when first installed, they loosened an inline fuse) -- I got a break on the parts and labor due to family employee. Voila! All is well. In fact, I never liked the wimpy headlights on the Marquis, compared to my BMW. I had switched to high intensity bulbs in the Marquis, but that didn't help much. BELIEVE IT OR NOT, WITH THE NEW MODULE THE LIGHTS ARE TWICE AS BRIGHT.
  • Can someone tell me if i have an LCM mod. on my 94 grand marquis? lights are going on and off after i have them on for awhile,inside and headlights.
  • Can someone tell me if my 94 Grand Marquis has an LCM module? My lights are going off and on even the inside lights to and there's a clicking like noise coming from the right side of the steering wheel.I can turn them on auto and the steady clicking starts and they start flickering off and on.
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 44,404
    No but there's something called an Autolamp Dual Coil Relay (headlamp relay) which is there, just right of the steering post under the dash.


  • roltyd22roltyd22 Posts: 21
    edited January 2013
    This thing is driving me nuts,i covered the sensor up on the dash trying to make it think it's nighttime and will not start acting up,It will do this at night could there be another sensor for the lights somewhere?
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 44,404
    There's a Daytime Running Light control unit:

    The Daytime Running Lamps (DRL)is located at center front of vehicle, on front of upper radiator support.


  • I checked all around and on radiator support..nothing but 2 bag sensors.Could it be elsewhere on my 94 grand marquis? I'm also going to leave the sensor on the dash covered until it gets dark and see what happens if nothing i'll remove tape and observe..hopefully not a light show,
  • I just removed the headlight switch and in the harness one of the wires where connected to switch was burnt and melted,i hope that's the to find a new harness i guess...think the switch is good or replace to be on the safe side?
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 44,404
    edited January 2013
    sounds like the switch overheated. I'd replace it unless it was punishingly expensive.

    "Fire...good. Fire in car....BAD!"

    sorry about the DLC...that's what the manual told me when I looked it up for you. In the diagram it looks to be more to the right (passenger) side of the radiator shroud, next to the outside temp sensor. This is a '94 GMarquis, right?


  • Your right about the fire,Hey i went to orielly's and got another harness,put it on and seems fine now lights not flashing.I'll just keep an eye out and see what happens now,thanks' for the help i appreciate it.
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 44,404
    Great! If you can, maybe feel the harness to see if it's getting hot.


  • Yes i did so far so good..i'll keep you informed on i can sleep tonight..thanks again
  • ct45ct45 Posts: 3
    Yes, it has an LCM. The part is ~ $500.00 from Ford and they will install it for another $400.00. If you are handy and know how to solder, this problem can be fixed by replacing a relay on the LCM circuit board. The relay is available on line for ~ $0.85 + ~ $3.00 shipping from Mouser Electronics.

    Somewhere on this string are pictures of where the LCM is located (under the dash to the right of the steering wheel) and the part # of the relay.
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