Wiring an hour meter to a 1978 Merc 800

1970Thunderbird

Petty Officer 2nd Class
Joined
Dec 24, 2009
Messages
111
Hey all,

I'm trying to wire in an hour meter to my 1978 Mercury 800. I'd like to run it into my wiring harness, which has seven wires: black, white, grey, orange, red, yellow and brown.

Which one is the accessory wire? And am I correct in assuming that it would power the meter only while the key is in the "on" position?

Thanks!
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,036
Re: Wiring an hour meter to a 1978 Merc 800

White is the Ign accessory wire. That is the best one to wire it to. Obviously the ground wire is black.
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: Wiring an hour meter to a 1978 Merc 800

If you have any other gauges on the boat, wire it to the "I" (ignitiion) and the ground terminal on any other gauge. If you have no gauges, then the POS wire gets connected to the "A" (accessory) terminal on the ignitiion switch.
 
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