Interior Light and Cargo light randomly comes on
 

2006 F350 interior and cargo light randomly turns on when truck is off. Ford mechanic said it was the security module which I replaced but it is still occurring. After engine is shut off about 15/30 minutes lights turn on for a few minutes and then shuts off and repeats until I unhook battery. When this happens there is a clicking under dash where wire harness (I believe from door) is connected (white block). Any help on the cause.

I had the same issue, complete with clicks and lights coming on, in our 2006 Ford F150. The tachometer and speedometer also intermittently quit working. The issue began after I replaced the ABS pump but I didn't associate it with that issue. I had checked fuses, used ForSCAN, and still couldn't figure it out - ForSCAN just told me that the module in the new pump wasn't working correctly.
Imagine my surprise when I disconnected the module, everything started working normally. I put the old module back in, and everything worked as it should.
Suggestion: Identify and disconnect modules until the issue goes away - you may get suggestions of where to start by using ForSCAN or the Ford diagnostic software. Like my issue, the module might seem unrelated to the issue that you are having.