Originally Posted by bottomline2
I can help with the tach wiring. I even have 1 plug in connector to bare wires for sale which could be used to splice into your harness.
System Check Gauge Wiring
Looking at the back-side of the gauge, holding it upright, the pin layout is:
Pin 1 = 12 Vdc VIOLET (Key Switch ON)
Pin 2 = Ground or battery negative BLACK
Pin 3 = Tachometer signal GRAY
A ground on the following pins activates the associated indicator:
Pin 4 = No Oil (OMS sensor) TAN/YELLOW stripe
Pin 5 = Low Oil (Reservoir float) TAN/BLACK stripe (new pick up kit available for pre 1996 models)
Pin 7 = Check Engine (fuel vacuum sensor) TAN/ORANGE stripe (not installed on older V4s but can be added)
Pin 6 = Engine Hot (cylinder head sensor) TAN
Pin 8 = Activate Aural Alert (supplies a ground to the horn circuit when any of pins 4 - 7 are grounded) TAN/BLUE stripe
The harness section I have has the plug for the horn. Of course you need 2 of them and only 1 warning horn.
Let me know if you have any more questions. I have lots of info on hand as I just converted a 1990 engine to 1996 and later controls, and system check and I didn't use any adapter cables to do it. I spent 2-3 months researching this in my spare time. I cut the big red plug off and used the new style connectors on my engine harness. IE my boat is ready for a post 96 repower when the time comes. Maybe even a 225HP ETEC!