I have a problem with the light switch in my boat and was wondering if anyone knows how to test the three way switch that controls the lights. When I plug in the back light it stays on at all times and when the front light is on the gauge lights dim and when the front light is off the gauges get bright. Kind of bassackwards from what I want, dont fish alot at night but have the McDonalds tournament coming up and need this to be working half way properly by then. Sorry for the long explanation, just need to know how to test both of the three way switches to make sure it is not a wiring problem. Thanks in advance for any advice.

sounds like you have a short, pull the front light or disconnect one of the wires if its a permanent mount and turn them on, if the guages stay bright you most likely have a short in the front light/wires.
could be the switch, take it out and with a meter or test light find the hot wire, touch it to the others one at a time and see if they work right, hook both front and rear and see if both work right. if the lights work right its the switch.

Have you checked the front of the boat? Depending on what boat you have , a lot of the bass boats have a second switch at the bow to turn on and off the lights. Yours may be in the Anchor mode.

I will try that and see if it works this weekend.

Well, Mike, I found more problems when working on the boat today. Tried running down the problem with the light switch and moved some wires around under the dash and got a little smoke. LOL Unhooked the batteries and traced the problem down to a wire that is supposed to be a ground since it is black, but now it has 12 Volts.

I was wondering if you have ever run into this before. It is a 1989 Yamaha Pro V 150, the wire comes from the main wiring harness from the motor and runs with a Red, Yellow, Green wire and this black wire that is carrying 12 volts. Have you ever run into this before? How did you solve this? Now my light switch seems minor. LOL Any help is appreciated.

still sounds like a short, what does the black wire hook to at each end?
do the others have 12v also?
if that is a ground then you have a dead short and you need to find the bare spot/spots that are contacting ground.

This is the black wire that comes into the main switch. it is carrying voltage from the motor wiring harness. Gonna get my volt meter out today and test it at the motor and then I will know if it has a bare spot in the harness itself. It will be fun fishing that big wire out and finding a bare spot in the harness it self, but I am sure I can do it. Thanks for the help.