1994 grand marquis keyless entry
 

How do I remove the keyless entry keypad? Also light staying on in keypad and keyhole lock at all times. I've replaced door jamb switch.

Sorry, Charlie -- but I can't find ANYTHING about removing your keypad.
I have the Factory Shop Manuals for the '95 Grand Marquis, and I seached high & low for the part number and/or any "Removal-Installation" proceedures or pictures of the back of the keypad that would help you get that keypad off.
I read one person on-line who said there was a "clip" that holds it on, which sounds reasonable.
Regardless, you're gonna have to take the interior door panel off to get at the back of the keypad. You MAY be able to see the keypad location area inside the door with a flashlight.
You MAY have to remove the window glass to access the keypad from the back side.
I have replaced the electric window regulator and motor, and the lock actuator -- but the keypad is still good and functioning well.
From what I understand, the keypad itself is rarely a problem -- I would suspect a faulty connector/module.
Another thought -- If your problem appeared suddenly, try this:
Remove the car's battery. Wash the battery and charge it completely with a slow-charger.
Dip the cable terminals in a quart of water/tablespoon baking soda solution.
Spray battery cable terminals with WD-40 before you re-install the battery.
After the battery has been serviced and out of the car for an hour, re-install (Positive cable goes on LAST!) the battery. Spray the terminals with WD-40 again.
Start the car and drive it for 10-25 miles to allow the ECM to re-learn the car's "habits".
The battery proceedure MAY not help your problem, but it CANNOT hurt anything.
Good Luck !!