Which parts fail
Components named in complaints (battery, alternator, wiring, ignition, instrument cluster, infotainment).
Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 2003 Mercury Grand Marquis owners, lightly cleaned up (personal details are redacted by NHTSA).
I started Mercury with foot on break like normal. Shifted into reverse. Car accelerated backwards at full speed. Brakes did not stop car. Attempted to shift into neutral but went into drive instead. Car accelerated forward at full speed with my foot still on break. Car hit metal post and tree knocking them down and dragging the tree 50 to 60 feet before stopping with my foot still on the break. Car had stopped accelerating. I turned off the ignition. This unintended acceleration had happened before. Two different dealers attempted to fix the problem. Both of them thought they had been successful but it happened again. Previously, applying the brakes stopped the car, but not this time. Someone could have been injured severely or killed.
The contact owns a 2003 Mercury Grand Marquis. The contact that the headlights were intermittently inoperable. Additionally, the contact stated that the instrument panel lights, the brake lights, and the turn signal lights were inoperable. The contact who is a mechanic, had inspected the fuses, the fuse box, and other unknown parts, but found no failures. The dealer was notified of the failure. The vehicle was not diagnosed or repaired. The contact related the failure to NHTSA Campaign Number: 15V861000 (Exterior Lighting); however, the VIN was not included. The manufacturer was notified of the failure and referred the contact to the NHTSA Hotline for assistance. The failure mileage was approximately 160,000.
The contact owns a 2003 Mercury Grand Marquis. The contact stated that the headlights and taillights were inoperable, and the trunk failed to open. Additionally, all the doors failed to manually lock, and while utilizing the key fob, the door locks were inoperable. The door-ajar message was displayed. The local dealer was not contacted. The vehicle was not diagnosed or repaired. The manufacturer was notified of the failure and referred the contact to the NHTSA Hotline. The contact stated that the failure was related to NHTSA Campaign Number: 15V861000 (Exterior Lighting). The approximate failure mileage was 179,000. The VIN was not available.
Its the LCM L(IGHT CONTROL MODULE)...HEAD LIGHTS went out on me one night coming down [redacted] causing me to wreck in a ditch and hitting a light pole
O.I.N. 11523223 05/22/2023 1. Lighting Control Module: Failure 2nd time. 2.Couldn't see where I was traveling. 3. No. 4. Yes. Inspected by myself, a Mechanic and Trouble Shooter. 5. Yes. Prior to the failure, the headlamps began flashing on and off. Previously the taillights failed. No warning. Lighting Control Module Defective. Replaced Module per Recall 14N01C. Ford Dealership, Pearson Ford, INC.10650 N. Michigan RD., Zionsville, In., [phone], Service Advisor: William Haygood
First issue: The headlights and door chime stay on after key is removed and lights are off causing battery to drain while vehicle is not being operated. Second issue: 50 amp ignition fuse blows randomly while car is in motion which causes a complete loss of power to the car including: braking power and power steering assist. The tilt steering being raised or lowered fixes the problem temporairly on occasion. A clicking sound from the lighting control module is heard when adjusting the tilt steering also
What is your vehicle sales or service issue?:I received a letter from the Ford company about getting my headlights replaced. My headlights does not work at all and I have to hold my high beams in order to have some lights at night in order to see. This is very uncomfortable when driving with one hand especially, when I have my babies in the car with me. When I went to the Ford dealership in March. They told me that the parts were on back order until June or July. I went back to the dealership (lilliston Ford in kingsland, ga)in the beginning of December 2014. They told me that the parts are still on back order and that they're are 3800 people waiting on those parts. I've been pulled over numerous of times because of my hands slipping off of the high beams and I've had 2 accidents because of my headlights. I need to be put in a rental car are something until my lights are fixed. …
Tl contact owns a 2003 Mercury Grand Marquis. The contact was driving approximately 30 MPH when the vehicle stalled without warning. There was a strong burning odor inside of the vehicle. The contact inspected underneath the hood and flames excessively ignited from the engine compartment. There were two bystanders who extinguished the fire with bottles of water. There were no injuries. The fire department arrived and a report was filed with no personal injuries. The vehicle was towed to an authorized dealer and the technician stated that the failure was contributed to the alternator. The battery, alternator and electrical system were replaced. The failure mileage was 63,073.
Tl* the contact owns a 2003 Mercury Grand Marquis. While driving various speeds, all the gauges on the instrument panel failed to provide the accurate reading. In addition, the air suspension that controlled the shocks failed to hold air. The vehicle was taken to perry's Ford (205 e hwy, holdenville, OK 74848, phone number: [phone]), but the vehicle could not be repaired because there was no one there who could remedy the failure. The vehicle was not repaired. The manufacturer was not contacted. The approximate failure mileage was 123,000.
Tl* the contact owns a 2003 Mercury Grand Marquis. The contact stated that all the warning indicators illuminated intermittently on the instrument panel for approximately five to ten seconds when the vehicle was being driven. The contact also stated that the blower motor failed to function. The vehicle was taken to an independent mechanic where the failure could not be determined. The vehicle was not repaired. The vehicle was not taken to a dealer. The manufacturer was not contacted. The approximate failure mileage was 80,000.
Electrical complaints in other Grand Marquis years
Frequently asked questions
How common are electrical problems on the 2003 Mercury Grand Marquis?
NHTSA has 51 complaints about the electrical system of the 2003 Mercury Grand Marquis, 14% of the model year's 362 complaints. The component named most often is ignition (1 mentions).
Is there a recall for 2003 Mercury Grand Marquis electrical problems?
No. NHTSA lists no electrical system recall for the 2003 Mercury Grand Marquis, though it has 1 recall for other components. If the problem is widespread, a repair may still be covered by an extended warranty or a manufacturer service bulletin — ask a dealer.
At what mileage do 2003 Mercury Grand Marquis electrical problems start?
Half of the complaints with a recorded mileage happened before about 95,000 miles, and 14% before 25,000 miles.
Is it dangerous?
Owners linked 4 crashes, 2 fires and 1 injury to electrical system problems on this model year. If you notice symptoms, have the car checked before driving further.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.