FORD: THE LIGHTING CONTROL MODULE HAS EXTENDED WARRANTY COVERAGE, ON CERTAIN VEHICLES, DUE TO A POSSIBLE CRACK ON SOLDER JOINT THAT CONNECTS RELAY TO CIRCUIT BOARD. MODEL 2003-2005 CROWN VICTORIA, GRAND MARQUIS.
full bulletin at NHTSA ↗2005 Mercury Grand Marquis lighting problems
moderate 242 complaints filed with NHTSA · avg repair $250 · see lighting across all vehicles →
Failure mileage
Complaints
242
Recalls
0
Avg fix
$250
When does it fail?
Of the 242 lighting complaints filed for the 2005 Mercury Grand Marquis, here's the actual mileage breakdown — failures cluster heaviest at 50,000-75,000 mi.
0-25k
25-50k
50-75k
75-100k
100-125k
125-150k
150k+
Each bar shows the share of total complaints filed at that mileage range. Peak failure window highlighted. Some owners report problems earlier; some make it well past 150,000 miles symptom-free. Maintenance habits and driving conditions shift the curve as much as mileage alone.
What stands out
Of the 4 model years of Mercury Grand Marquis we track for lighting problems, this one carries the most owner complaints on file — 242.
Lighting accounts for 50% of every owner complaint on file for this vehicle — the dominant problem area across 12 categories tracked.
Is there a fix? Manufacturer service bulletins
The manufacturer has issued service bulletins covering lighting on this vehicle — documented repair instructions, service campaigns, or warranty extensions sent to dealers. A TSB isn't a recall (it's not a free safety remedy), but it's the manufacturer acknowledging the issue and how to fix it.
Source: NHTSA manufacturer communications. Bring the bulletin number to your dealer or shop.
The failure pattern owners describe
Owners of 2005 Mercury Grand Marquis vehicles describe sudden, random headlight failure while driving at night—the lights simply cut out without warning. Some report both low beam and high beam become unresponsive to the switch; others find that holding the high-beam flash lever briefly revives the lights, only to have them die again. The failure always happens at night or in darkness because that's when headlights are in use. Dashboard and tail lights often stay on, making the failure worse: oncoming drivers can still see the vehicle, but the driver is in total darkness.
The issue traces to the Lighting Control Module (LCM), a component with a documented internal circuit defect. Multiple owners report flashing high beams, cycling the light switch, restarting the vehicle, or waiting 10–30 minutes before lights return. One owner held the high-beam lever for an entire drive; another replaced the light switch ($137) only to discover the real culprit was the LCM. Repair cost is steep—$500–$700 for the part, $200–$300 labor—and parts have been on chronic backorder since Ford's partial recall in 2014–2015. Some owners waited months without resolution. One Ford dealer acknowledged replacement LCM modules from the factory have failed again shortly after installation. The 2005 model year is unique in design; 2004 and 2006 LCM parts will not fit.
Failure modes owners describe
Intermittent headlight failure—complete loss of beam
Headlights shut off without warning while driving, both low beam and high beam non-responsive. Other lights (parking, tail, dashboard) often remain functional. Headlights may return after minutes to hours or after vehicle restart, or only when holding the high-beam flash lever. Pattern is unpredictable and worsens over time.
When: Typically 35,000–150,000 miles; often occurs at night or in dark conditions
Symptoms owners cite: Sudden loss of both headlights while driving; Headlights unresponsive to switch position (auto or manual); Interior/dashboard lights remain on; Headlights return after random delay or vehicle restart; High beams work only when flash-to-pass lever held back; Lights cut out when using turn signal or wipers in some cases; Intermittency increases in frequency over weeks to months
Repairs/costs cited: Light Control Module (LCM) replacement or repair. OEM part cost $500–$700; labor $200–$300. Some owners reported reseating connectors temporarily resolved symptoms. Dealers report severe parts shortage and long backorders; replacement LCM modules from OEM have also failed in some cases.
Recalls/TSBs owners mention: Ford issued Customer Satisfaction Program 14N01 (April 2014) and Recall 15S39 (2015); however, parts supply was critically constrained for years. Many 2005 model year vehicles remain ineligible for recall coverage despite identical failure mode. Ford redesigned the LCM for 2006+ model years but did not issue full mandatory recall for 2005 Grand Marquis and Crown Victoria. Some dealers reported being instructed to install replacement LCM modules that were also defective.
Lighting Control Module (LCM) defect—documented in internet forums
The LCM has been identified by multiple owners and technicians as having an internal design flaw, specifically a bad circuit that causes headlight dropout. The module earned the informal nickname 'Lights Out Module' in online automotive repair communities. 2005 model year is unique; 2004 and 2006 LCM parts are not interchangeable.
When: Typically 50,000–100,000 miles; can occur earlier
Symptoms owners cite: Module fails internally; no bulb or wiring issue detected; Repeated failure even after module replacement with OEM part; Requires hold on high-beam lever to operate headlights
Repairs/costs cited: LCM replacement; part number 5W7Z-13C788-AC. Cost $500–$650 part only; total repair $800–$1,000+ installed. Junkyard parts also depleted (owners report 2005 wrecks already stripped). Some dealers have sold old design LCM units that fail again.
Recalls/TSBs owners mention: Ford redesigned LCM internally for 2006+ to prevent failure. Acknowledged awareness of problem, especially in Crown Victoria Police Interceptors. However, declined to issue full recall for 2005 model year grand consumers. Customer Satisfaction Program 14N01 and Recall 15S39 attempted to address but were hampered by parts shortage.
Headlight intermittency tied to turn signals or wipers
Headlights fail or flicker when turn signal is activated or when wipers are engaged. Owners note headlights come on when flashing high beams manually.
When: Variable; some occurrences noted within 35,000–75,000 miles
Symptoms owners cite: Headlights cut out upon turning signal lever; Lights flicker when wipers activated; High beams work if flash-to-pass lever held manually; Lights may come back on when another control cycled
Repairs/costs cited: Suspect LCM module or headlight control wiring. Some owners first replaced headlight switch ($137–$300) without success, then identified LCM as root cause.
Recalls/TSBs owners mention: Dealers initially suspected headlight switch failure; incorrect diagnosis led some owners to replace switch unnecessarily. No TSB or warranty program specifically addressing switch-to-headlight interaction.
Complete failure of multiple lighting circuits (headlights, taillights, dashboard)
In some instances, headlights, taillights, and dashboard illumination all shut off simultaneously, leaving only hazard flashers functional. This creates acute safety hazard because other drivers cannot see the vehicle and driver cannot see road.
When: Sporadic; reported at 50,000–150,000 miles
Symptoms owners cite: All exterior and interior lights go dark at once; Hazard/flasher lights may remain operational; Gradual recovery after several minutes or restart; Repeat occurrences within same trip
Repairs/costs cited: LCM controls entire lighting circuit in 2005 model. Replacement required.
Recalls/TSBs owners mention: Ford acknowledged this is a complex failure affecting multiple systems; no expedited recall or emergency parts program deployed despite safety criticality.
Synthesized from 242 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 9 most recent
2005 mercury grand marquis. Consumer requests NHTSA investigate head lights control module *tgw the consumer stated the headlights stopped working after 10 minutes. The lights went out several times while driving early in the morning hours and at night. The control module was replaced at a cost of $ 684.54.
Tl* the contact owns a 2005 mercury grand marquis. The contact stated that while driving approximately 65 MPH, the headlights and taillights failed. The failure occurred on a intermittent basis. The vehicle was inspected by a dealer who informed the contact that that failure was caused by a defect in the lighting control module. The vehicle was not repaired. The failure mileage was approximately…
At any given time the lights just go out and I can only see by manually using the high beam lights. The lights will come on for a few moments then out they go again. You can hear a clicking sound when it is goes out and back on. This is extremely dangerous especially since I have 3 children in my vehicle and any given time. *tr
The headlights on the vehicle went out while driving on the highway. Parking lights stayed on and flashers worked allowing to get the car to the break down line. This has happen about 8-10 times since the first. In checking for a fix, I found there are a number of companies offering a repair solution and this looks like a common and dangerous problem that occurs often. I noticed this has been…
While driving with headlights on at night the headlights turn off. After stopping and turning car off and restarting engine the headlights eventually start working again. Happened multiple times the same night. *tr
Tl* the contact owns a 2005 mercury grand marquis. The contact stated that while driving at night, the low beam headlights suddenly failed. The vehicle was not diagnosed or repaired. The manufacturer was not notified of the failure. The failure mileage was 113,000.
Nighttime, turned car off in drive through line at fast food place 185 miles from home. Have light switch on automatic. Turned car on and drove off only to realize that my headlights were not on. Stopped in adjacent parking lot and began playing with the switch, turning car off and on, trying to figure out how to drive three hours with no lights... High beam flash mode would function, but…
Head lights go on and of by itself while driving
Tl*the contact owns a 2005 mercury grand marquis. The contact stated that the headlights shut on and off intermittently; however, the high beams continue to function. The headlight switch was replaced, but that did not correct the failure. The dealer stated that headlight module caused the failure. The contact was concerned about the safety issue. The failure and current mileages were 60000.…
Had lighting trouble with your 2005 Mercury Grand Marquis?
File a complaint with NHTSA → It's free, official, and how every report above got here — owner filings are the federal safety record this page is built on.
Common questions
How serious is the lighting problem on the 2005 Mercury Grand Marquis?
It's a documented issue but not catastrophic. 242 complaints have been filed. Repairs average $250 and most owners catch it before it causes a breakdown.
At what mileage does the lighting typically fail?
Across the 205 complaints that reported odometer mileage, most lighting failures cluster between 54,500 and 104,000 miles, with the median around 79,000. A quarter of owners report trouble before 54,500; a quarter make it past 104,000. Maintenance history matters more than the odometer alone — this is the reported failure window, not a guarantee.
What does it cost to fix?
Independent shops typically charge around $250 for lighting repairs on this vehicle. Dealer pricing tends to run 20-40% higher. The exact figure depends on the specific failure mode, parts availability, and your local labor rates. If you're outside factory warranty, an extended service contract often covers this category.
Are there any recalls related to lighting?
No active recalls currently cover lighting issues on this vehicle. The complaints filed represent owner-reported failures that haven't risen to the level of a manufacturer-issued recall — but they're still worth knowing about before you buy or budget for repairs.
Related
Complaint and recall data sourced from the National Highway Traffic Safety Administration (NHTSA)
public records database. Verify the raw federal record at
nhtsa.gov/vehicle/2005/Mercury/Grand Marquis.
Severity ratings are derived from reported crashes, fires, injuries, and fatalities. Repair cost estimates are
independent-shop national averages and may differ in your area. Some links on this page are affiliate links.