Holman~Moody Marine Tacometer wiring diagram ?

[silverghost]

I am trying to wire-up my old 1972 Holman~Moody Marine Donzi 18' Tachometer.
It came in a box of removed boat parts~

There are four wires comming out of it's case~

White
Yellow
Red
Light Blue

I assume one is for 12 Volt Battery Pos+ hot when the ignition keyswitch is turned on ?

One is Neg - ground ?

One is for the ignition coil's ponts opening & closing RPM pulse counting ?

And one is for a Tachometer gauge backlight ?

But Which color is connected to what ?

I also have a NOS 1970s Donzi 18 wiring harness in a bag with & extra gauge panel short plug-in harness that I bought from a former NJ Donzi 60s-70s dealer "Stone Harbor Marine"

I also could use the 1970s Donzi 18 wiring diagram color codes for the entire OEM boat wiring~~~But I suppose I coud figure those out myself if I have to ?

The Tachometer wiring is still an enigma ?
And I do NOT want to wire it incorrectly and burn it out.

Does anyone here know how the old Holman~Moody Marine Tachometer is wired ?

How about an entire boat wiring harness color code diagram for the entire 1972 Donzi 18 ?

It appears Donzi had NO FUSE panel on the wiring harness in 1972 ?
Was this true ~~~No FUSES~~~at ALL ?

Any ideas, or help appreciated !
Thank's

[SanDogDewey]

This should help.

Wiring Diagram.jpg