Tach wiring question, OMC tach

[dave37]

I've been given a tach, OMC model 174052. It has the following wires, blue, grey,purple and black. Any ideas what each wire is for, hoping to hook it up to the tach plug on my 1985 Mercontrol.<br /><br />Thanks!

 

[gaugeguy]

Re: Tach wiring question, OMC tach

Blue...lamps, to light switch<br />grey...tach signal input<br />violet...+12v from ignition switch<br />black...ground

 

[dave37]

Re: Tach wiring question, OMC tach

Thanks very much!