20 Most Recent 2003 Mercury Grand Marquis Questions & Answers


the fuel tank or filler pipe is not venting, remove the vent hose and or the portion that connects the charcoal canister and check for anything that may be clogging it, I have found them full of charcoal in some vehicles

2003 Mercury... | Answered on Sep 08, 2019


There is actually a possible recall on this issue as it is a known problem with the LCM, or Lights Control Module. Go to the following site:
http://www.arfc.org/complaints/2003/mercury/grand_marquis/

This is one of the complaints:
HELLO, WE HAVE A 2003 MERCURY GRAND MARQUIS THAT HAS A PROBLEM WITH THE HEAD LIGHTS SHUTTING OFF AT RANDOM TIMES. NOTHING GAVE WARING TO THIS PROBLEM HAPPENING, WE BOUGHT THE CAR USED, AND WAS JUST FINE FOR A YEAR, THEN ALL OF A SUDDEN ONE DAY THE HEADLIGHTS JUST GO OUT. THE FIRST TIME IT HAPPENED WAS ABOUT 6 MONTHS AGO(3-1-10). NOW EVERYTIME IT IS DRIVEN WITH THE HEADLIGHTS ON, IT IS GUARANTEED TO HAPPEN AT LEAST ONCE AND SOMETIMES UP TO 5 TIMES JUST IN 3 MILES OF DRIVING ON MY WIFES WAY HOME FROM WORK. THE ONLY WAY TO GET THE LIGHTS BACK ON AFTER THEY GO OUT IS TO PULL OVER TO THE SIDE OF THE ROAD, SHUT THE CAR OFF, LET SIT FOR A FEW MIN, THEN START AND THEY WORK AGAIN FOR A BIT. THIS IS OVERALL VERY DANGEROUS AND SUPRISING THAT WE HAVE NOT BEEN IN AN ACCIDENT OR RECIEVED A TICKET YET! I AM A ACTIVE MEMBER ON A CROWN VICTORIA FORUM, AND WITH LITTLE SEACHING ON THAT SITE OR GOOGLE YOU WILL SEE TONS OF REPORTS OF THIS BEING A VERY COMMON PROBLEM ON THE 2003-2005 CROWN VICTORIA, GRAND MARQUIS, AND MERCURY MARAUDER. WITH THE HELP OF OTHER MEBERS ON THAT FORUM IT WAS FOUND TO BE A FAULTY LCM(LIGHTING CONTROL MODULE) WHICH HAS A PROBLEM WITH OVERHEATING LIGHTING RELAYS. THE ONLY WAY TO REMEDY THIS PROBLEM IS TO PURCHAS A NEW LCM FOR ANYWHERE BETWEEN $250 AND $600 WITH NO GUARANTEE HOW LONG THAT PART WILL LAST. I ACTUALLY PURCHASED A NEW ONE TODAY. VERY EXPENSIVE FIX JUST FOR THE USE OF HEADLIGHTS, BUT I VALUE MY FAMILIES SAFETY MORE. I WILL BE KEEPING MY OLD LCM TO POSSIBLY HAVE IT REPAIRED FOR WHEN MY NEW PART FAILS AGAIN. THANKS SO MUCH.

2003 Mercury... | Answered on Jul 13, 2019


Theres a good chance you have a broken wire or wires in the drivers door wiring where it has to flex. I hope this helps. Take care.

2003 Mercury... | Answered on May 12, 2019


You don't need to rewire anything - driveablity problem . Do yourself a favor an take it to a qualified repair shop . All you'll do is make it unusable .

2003 Mercury... | Answered on Jan 26, 2019


Have you checked the transmission fluid level?

2003 Mercury... | Answered on Jan 14, 2019


It is not going into neutral. Your overdrive band is fried on your transmission. Typical problem on these transmissions. Transmission will need to be completely disassembled to get to the overdrive band. Complete overhaul. Recommended when you read the owners manual to not drive these uphill for long periods of time without shifting to regular drive.

2003 Mercury... | Answered on Oct 08, 2018


1. Simple answer...you may be low on antifreeze or water in the radiator. Add some to fill it up, and try again. DO NOT OPEN THE RADIATOR CAP HOT!!! Add to the overflow reservoir.

2. Check the manual lever is still moving the flapper/air blend door on your heater under the dash.

3. It could be worse, if the heater core is plugged.

2003 Mercury... | Answered on Oct 08, 2018


It is a simple but fiddly job. Examine where the arm rest hinges. There will be curved plastic covers. These should just pull up and off. It will reveal a silver pin with a black lock washer fitted on the end furthest from the door.
Using a pair of thin flat bladed screwdrivers and a LOT of patience, you should be able gradually lever the locking washer off the pin. If your careful you should be able to reuse the washer. Once the washer is off, the pin should tap out towards the door. The arm should lift up and out.
you might need to tilt the back of the seat to get better access.

2003 Mercury... | Answered on Jun 07, 2018


Sounds like the fuel filter

2003 Mercury... | Answered on Mar 01, 2018


The average person does not have pressure gauges or the specs for power steering pressure. These readings would show if the power steering pump pressure is correct and then pointing to the problem being inside the rack and pinion unit.

You may be able to take the pump into a hydraulic repair shop and have its performance taken. Although they may not know what rpm your pump needs to be turning for a given pressure performance.

Could be a procedure for air bleeding is special. There was a procedure for Ranger or Chevy S10 type trucks which had strange elevation requirements for fluid to be "burped" with hoses hung higher than pump case. Once air escaped higher elevated hose, system was primed.

Make sure of simple things, like fluid is correct type. Maybe some other Expert will supply more answers.

2003 Mercury... | Answered on Jan 17, 2018


  • Insufficient, erratic, or no heat
  • Low engine coolant level.
  • Engine overheating.
  • Plugged or partially plugged heater core (18476).
  • Temperature blend door binding/stuck.
  • Temperature blend door actuator (19E616).
  • Incorrect heater control valve (18495) operation.
  • Go To Pinpoint Test I .

Are the heater hose's going through the fire wall hot ?
I2 CHECK FOR HOT WATER TO THE HEATER CORE INLET HOSE WARNING: The heater core inlet hose will become too hot to handle and may cause serious burns if the system is working correctly. Allow the engine to reach normal operating temperature. Feel the heater core inlet hose.
  • Is the heater core inlet hose too hot to handle?
Yes GO to I4 .

No REFER to Section 303-03 to check cooling system function.

2003 Mercury... | Answered on Jan 06, 2018


This vehicle does NOT use a heater control valve. Coolant flows to the heater core at all times. Temperature is regulated by the blend air door and blend door actuator. Locate the blend door. Remove the actuator and open the door by hand. If you get heat, the actuator or the control head is bad. FWIW, the actuator is the most likely cause

2003 Mercury... | Answered on Jan 06, 2018


Under the car. You need a tool and you need to release pressure before changing.

2003 Mercury... | Answered on Dec 06, 2017


check the back of the radio, make sure than the antenna, connector is plug into the radio, if it is, then replace the radio.

2003 Mercury... | Answered on Aug 22, 2017

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