To adjust the parking brake on a 2005 Grand Marquis, first, ensure the vehicle is on a level surface and the rear wheels are chocked. Locate the parking brake adjustment mechanism, which is typically located under the car near the rear of the vehicle, and adjust the cable tension using a 10mm wrench. You can also check the brake lever for proper engagement; it should hold the vehicle on a slight incline without slipping. Finally, test the parking brake by engaging it and ensuring it holds the vehicle securely.
driver's side , inside the car, near the parking brake.
I believe the obd port is located by the parking brake and just above it.
adjust the shoes
The red " BRAKE " light in your dash means that either your parking brake is on or the BRAKE FLUID LEVEL in your brake master cylinder in the engine compartment is LOW
Adjust or replace the stoplight switch at the upper end of the brake pedal under dash area
Fuse location 8 (20 amp) in the instrument panel fuse box, drivers side by the parking brake.
with tools
DOT 3
grand marquis
According to the 1996 Mercury Grand Marquis Owner Guide : ( DOT 3 brake fluid , meeting Ford specification ESA-M6C25-A )
Check the brake light switch ,on the brake pedal. Might need adjusting.
Could be the tires, or your front brake rotors