the remote entry keypad isn't battery powered unless it is a dealer add on. If it is a dealer add on, then it just pretends to be a keyless entry FOB and the car is programmed to allow the fobs, so nothing needs to be done.
Do you mean a keyless entry fob, the thing with lock, unlock, etc and not numbers? They should still be recognized by the vehicle after you swap out the battery. Some aftermarket ones don't, generally they should. If you got a replacement fob for an aftermarket setup then you might need to program it back in. The two way pager one I have to disarm it 3 times before it recognizes the fob again, it works from the car to the fob (it tells me the cars status) but not from the fob to the car until I disarm three times.
A forum community dedicated to Ford Thunderbird, Mercury Cougar and Lincoln Mark owners and enthusiasts. Come join the discussion about performance, modifications, troubleshooting, maintenance, and more!