TOPIC: Tach wiring?

Hey Merc friends, I need help wiring up my original quicksiler 72 tach. I have the wiring harness coming out of the control box, (blac, brwn, whit)up to the tach.

On the back of the tach it has an isolated post marked +pos, and a second isolated post marked -neg. The other two post are mounted to the back of the brass plate for mounting.

The best I can remember taking it apart two years ago, the brown went on the +pos and the black to the -neg. The white is a switched 12v for a light in the tach.

Any help will be appeciated! Mike

Brown=pos. Black=neg. White is for the light and the other is your signal wire ( may be Blue ).

My harness only has the 3 wires - brown, black, and white. Same wiring directions minus the blue?

Mike, usually there's power, ground and signal for a tach. If brown is power and black is negative or ground, I don't get where the signal is coming from. Usually it's a blue wire. Maybe that's not the case with merc tachs and somebody will jump in here!

Good luck with it. Let us know what happens.

Frank

I was finally able to catch a Merc Doctor in town today and looking thru his service manuals here is the scoop on wiring up a vintage tach on an inline 6 "with" a distributor.

As you face the "back" of the tach---ther are two isolated post. The left post is marked "pos" and the right is marked "neg".

Coming out of the shift control box, using the 3 wire plug connector, you have a brown wire, black wire, and a white.

Black wire goes on the left marked POS, brown wire goes on the right marked NEG, and the white wire is used to run a light bulb and other gauges as installed like a "volt" gauge.

There ya have it. thanx