Hi!
I have been having this issue for about 2 years and we cannot find the issue.

The car will start normally sometimes and wont start and wont cranck at all some other times.

I read many posts but cannot put my finger on it. The started and battery are good. The alternator works. In fact the car works great. Recently I thought I had solved the problem by replacing the rear side marker light fixture but. The light works now but the warning comes back. Very weird. It seems to affect the alarm system and prevents car from starting.

I would love to find a solution to this problem if anyone has a clue...

 

I had this issue a few years ago in my 1999 Ram. Turned out to be a faulty ignition switch. Replaced it with a new one from NAPA, and my Ram immediately began starting properly each and every time....

 

On my XJ6 I had the same problem and I learned that if I whacked the gear shift then it made the microswitch that detects you're in Park work.

Try some gentle violence. Just move the gear shift sideways a bit if it doesn't start.