Guage wiring question

rbrt_rex

Cadet
Joined
Jul 25, 2011
Messages
7
Rewiring my Yamaha gauges(multi tach, volt, pressure and temp) for a 1988 130 ETLG.
I have 3 wires out of the ign harness that go to the gauges, yellow(+12v key on), black(ground) and green(tach send). The gauges have a blue lead that is daisy chained from gauge to gauge for lighting. My question is, is it acceptable to tie the yellow(+12v key on) lead to the blue lead to power the guage lights, since i will not be running my gauge lights on a switch?
 

Fireman431

Rear Admiral
Joined
Sep 17, 2007
Messages
4,292
Re: Guage wiring question

It may work, by my personal opinion would be to have the tach's power feed supply only the tach. the tach should have a light on it as well. Why would you not tie in your tach light to them and put them on a switch. The way you worded it, the gauge lights would be on whenever the engine/key was on...correct?
 

rbrt_rex

Cadet
Joined
Jul 25, 2011
Messages
7
Re: Guage wiring question

The yellow(+12v key on) not only powers the tach, it has a pigtail off of it to provide power to the other gauges as well as they are all daisy chained with a yellow lead. I just need to pick up +12v to feed power to the guage lights that are too daisy chained. As best as i can figure, by connecting the yellow(+12v key on) would also provide power to the gauge backlights when the key is on.
 

Fireman431

Rear Admiral
Joined
Sep 17, 2007
Messages
4,292
Re: Guage wiring question

If the gauge lamps are on every time the key is on, you are going to run into burned out bulbs (when you may actually need them) and possibly heat/burn marks on the gauge faces if they get too hot. Put them on a dash switch, even a simple single pole toggle.
 

rbrt_rex

Cadet
Joined
Jul 25, 2011
Messages
7
Re: Guage wiring question

I see your point with the switch and will definately go that route. Currently there is a 3 amp fuse inline for the yellow(+12v key on that runs to the guages, is that fuse size sufficient for power to 3 guages?
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,771
Re: Guage wiring question

Yes. Gauges themselves draw very little power. If you run instrument lights from that same circuit (separate switch or not) then that fuse may not hold. But since the wiring in that circuit is likely about 16 gauge you can up the fuse to 5 amp or whatever it takes but do not exceed the capacity of the wire.
 
Top