Regardless of vehicle make, model, or age, when vehiclcle brake lights remain on when the brake pedal is not depressed, the cause is that the linkage between the brake system and the switch is improperly adjusted, OR less commonly, a defective switch.
Most likely cause would be a blown fuse.
According to the 2005 Mercury Grand Marquis Owner Guide : ( 19.0 US. gallons )
What fuse is for the 2005 Ford mustang Rear Brake lights?
In the Gas Tank
owners manual.
on top of gas pedal
For a 2005 Mercury Grand Marquis : " regular " unleaded , 87 octane According to the Owner Guide
can someone help me I can't find where the fus is for brake lights and what is the amp number for a dodge straus 2005
According to the 2005 Mercury Grand Marquis Owner Guide ( and one of Fords websites ) The ( Motorcraft FL-820-S engine oil filter is used )
Unbolt it from the floor.
most times if brake lights are stuck on you have a bad brake light switch on pedal under dash
Physically, yes. It would be best to consult an interchange reference to know if the wiring and programming are compatible.