on the coils nears the left front headlight it has 3 wire and the black one is disconnected where does that wire go...can that be the cause of my tach and radio shuting off and backfiring when i drive at night only at night day time its fine cus i dont have to use my headlights on

 

The tach signal is from the trailing coil, not the leading.

The radio shutting off at night would be unrelated, but probably because you have a bad alternator.

The extra wire is probably the test connector for the coil.