How to Override the Security System on a 1998 Grand Marquisby Emily Retherford
The 1998 Mercury Grand Marquis features a SecuriLock anti-theft system that immobilizes the vehicle if someone without a properly programmed key tries to start it. Once the security system is activated, the engine won't start until you override and reset the system. Fortunately, the process only takes a few minutes to complete, so you will be on the road again quickly.
Put the SecuriLock programmed key into the driver's side door and turn it counterclockwise to unlock the car.
Put the key in the ignition. Turn the key from the "Off" position to the "Run" position and keep it there for at least one second. The indicator light on the dashboard should remain lit for three seconds and then shut off, indicating that the system has been overridden.
Turn the key back to the "Off" position and remove the key. The LED indicator light should begin to blink, indicating that the SecuriLock system has been reset.