New Tach Install

[redfisher1]

I bought a new tach for 1971 800 Merc. it came with wire harness male plug that will plug right into the female plug on the remote control box. My problem is I seem to have more wire than a hook up for them.
The tach has a positive +, and a neg. - screw on the back and that's it. My harness has 3 wires brn. wht. blk. The tach is new or at least never been installed, on the back it states for 1971 thru 1975 merc. engines only
part # M0386180 if that helps any info will be very helpful.

 

[Moody Blue]

Re: New Tach Install

Are you sure there is not another terminal marked "S" or something similar? Should also be two terminals for backlighting. I think that vintage of tach used a signal from the switchbox (brown terminal) for the tach. Newer tachs would be connected to either of the stator wires instead of the brown terminal.

The wires from the tach harness are brn (tach signal), wht (+12V) and blk (Gnd). What model tach did you buy? Any pictures?