thats my question to you
You can't. It's factory set and cannot be changed.
look on the trunk hinge there should be a sticker with the code on it
you need to replace the the keypad on the door....the membrain has cracked and is letting moisture in.....if you leave the headlights on auto you will find they will go on and off too
The door code for 2000 Mercury Grans Marquis is usually factory programmed into the keypad. <><><> In SOME cases, the factory door code is printed on a sticker placed on one of the hinges of the trunk lid. Take a look and see.
One explanation for this is that you have a bad wire in your wire harness. go to o' Reillys and buy a wire tester and test the wires in you wiring harness. NO...if you have a keypad on door, water has gotten in and shorted out keypad causing conductivity between keypad numbers. keypad needs replacing. TSB for this.
You can find the keypad entry code for a 2005 Mercury Mariner in the owner's manual. You can also find it by contacting the dealership.
They are usually in the trunk
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Check on the right trunk hinge. I have an 03 model and it a 5 letter combination on a small white tag on the hinge.
Usually on one of the Trunk Lift Rods.
You cannot reprogram it. A dealer can get you the Master Code if you've lost it.