One problem related to fog light switch has been reported for the 2004 Mercury Grand Marquis. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2004 Mercury Grand Marquis based on all problems reported for the 2004 Grand Marquis.
Vehicle headlights went out at highway speeds with no apparent warning. Pulled over and examined lights, only fog lights working. Turned off vehicle and restarted, lights worked. Sporadic lights working, then not working. Able to manually pull and hold dimmer switch to activate bright lights. After researching this problem on the internet I have discovered the problem is the same all across the country in the 2003-05 Mercury Grand Marquis. The lighting control module (lcm) is problematic and poses a safety concern for many owners. . Read more...