Toggle switch wiring

[Bayou Dave]

I must not be smarter than a 5th grader. I want to install an on/off illuminated toggle switch for a depth sounder. The one I have has only markings of 1,3 and 4. I assume 1 comes from the ignition but don't know if 3 or 4 is the ground for the switch or which one is for the positive to the depth sounder. In the photo, from left to right the posts are numbered are 3,4,1.

 

[bruceb58]

You may have to do some trial and error testing. Hook 12V to one of the pins and connect a light which has one leg hooked to ground to each of the other pins. Once you find that combo that turns on the light bright, you have found the common and the load pins and the other pin is the light ground.

To determine whuich one is going to be hooked up to your ignition. connect that pin that you have determined to be the light ground of the switch to ground and hook up power to each of the 2 pins with the switch turned off. The light in the switch should be off when you have the voltage source hooked up to the common/input terminal.

 

[Bayou Dave]

I did the trial and error thing. Found out that #4 is the switch ground. #3 goes to the ignition and #1 goes to the positive depth sounder. I hooked up the wires a couple of ways to a extra bilge pump I had and got it to work only with the switch on. Thanks for the suggestion Bruce.