Don't have a 400 book, but the 600 (probably the same) has 4 wires to the coil unit. 2 are Orange and white... they tie together in the wiring harness and become one. There is a white wire... it goes to the IGN Control Module . There is a Black and Yellow which also goes to the IGN Control Module.
The connexions probably are not marked.
Good Luck..
JR
Lake Livingston, TX