Mercruiser 1970's gauge wiring

[timmynz]

Hi there,

I'm trying to change the oil pressure gauge and water temp gauge on my boat with a 305 and a alpha one stern leg. I was hoping it would be a straight swap over but I think the poles are arranged in an abnormal way and I can't figure out how the wiring works.

I've have been scouring the internet for about 10 hours but can't find any info about the gauges or how to wire them up?

Here is a link to a dash that is the same as mine: https://picclick.com/Vintage-MerCru...t-Cluster-Dash-173311120131.html#&gid=1&pid=2

Here is a photo of my actual oil pressure gauge wiring here: https://1drv.ms/f/s!AkHu3Kl0K32Pg9cQJsh3ipJLxlG2Bg


The oil pressure gauge has the model number: 59056a1 and the water temp 59054a1.

Is the big back cable going to the top left pole of the oil pressure gauge the negative?
Would the white cables be positive from the ignition?
Does that make the bottom left signal?

I have tried wiring up the oil pressure gauge with this presumption but it does not work.

As you can tell this stuff is very new to me and am perhaps over my head. Any help would be greatly appreciated.

 

[alldodge]

You have the older wiring color code

White - Ignition power
Black - Ground
Green - Water Temp
Orange - Oil Pressure

Each gauge gets a Black and White to power it up. Also looks like the Wite also goes to the lamps to light up the gauges when ignition is turned ON

 

[timmynz]

Wow thanks for your prompt reply. That was super helpful and have now got both of my new gauges installed and working.

Thanks for your help!