I have a 96 forman 400 that the first time you start it after having sat for at least 1/2 hour the oil light doesn't come on when you turn on the key. After you start it you can hear the tappets quiet down so I know I've got pressure. Once I run it a few minutes then you can shut if off and the light works normally until it sits a while again. I have replaced the oil sending unit on the bottome of the engine and checked the wiring as best I could. Any suggestions before buying the expensive control unit?thanks.