2001 Lincoln Continental Interior Lights Go On & Off

I purchased a 2001 Lincoln Continental w/ 55000 miles a few weeks ago. The interior lights on the car will go on and off continuously when the car is parked. They do not do this when the car is running. I found some old receipts in the glove box where the previous owner replaced the driver's door keyless entry keypad. I tried it one time with the factory code and it worked, but I could never get it to work again. The lights go on when these keys are depressed, so I am thinking I may have a defective keypad again. Am I on the right track or could it be the Lamp Control Module or something else? Thanks for any suggestions.