Three problems related to exterior lighting have been reported for the 1999 Mercury Grand Marquis. The most recently reported issues are listed below.
Tl- the contact owns a Mercury Grand Marquis. The contact stated while driving approximately 40-45 mph the vehicles head lights stopped functioning independently. The failure happened without warning. The vehicle was taken to independent mechanic diagnosed that the control module behind the dashboard malfunctioned and it needed to be replaced. The vehicle was not repaired due to parts no longer being manufacture red. The manufacturer was not made aware of the issue. The approximate vehicle failure mileage was 140,000. Kh.
The 3/4 key on the driver side door randomly quit working. Every other button still works, and when any button other than the 3/4 key is pressed, the keypad lights up. My key code includes the 3/4 key though, so I cannot use this keypad to unlock my vehicle or trunk. However the keypad lights up on its own, which causes my exterior and interior lights to illuminate. These lights cycle on for about 15 seconds and turn off for about 30 seconds. I had to remove my interior dome lights because they would drain the battery. If I am parking for an extended period of time, I have to disconnect my battery so the lights will not drain it. The Ford dealer checked for a recall on the lcm, but the recall does not affect the 1999 model.
Lamp cover fogging, when wiped clean the fogging immediately returns. Nlm.