I have a 89 xj and having a hard start problem and got to looking at the coil an noticed it had 3 different places for plug (not plug wires) a plug into.the third one doesn't have anything plugged into it.Are there supposed to be something plugged into it or is it supposed to just be empty.

 

My 89 just has 2, one is the coil power wires and the single one is the tach. There's a spot there for a 3rd but mine doesn't have anything there either.