There are four buttons on my 1997 Tracker, bought used and the labels have worn off. I know what two of them are for, running lights and livewell pump. The other two, I don't know. Maybe bilge pump is one. How can I tell what each is for?

Also... I know little about electronics but it's too expensive to take a boat into the shop to do this and that unless I just have to. I guess I need a multimeter to help fix things like... running lights quit working... livewell pump quit... bilge pump not working... gauges don't work (tach does work)... onboard battery charger doesn't work.

For instance, the livewell pump, how can I tell if it just 'went bad?" Might be a fuse? It worked up to last week and now I hear nothing when I turn it on.

There is a fusebox housing several fuses under the console. I don't see a label for what each fuse is to... bummer! How can I tell what each of the fuses is for?

When I get a multimeter, can someone explain the process of what to do to analyze what is the problem with any broken device? I need to determine if power is flowing through? How, exactly?

Also, see this first photo below? This is a master switch that the former owner installed. I'm not sure what it's for. And let me ask... the guy said if I left it "on," it would, over time, drain the battery. Why?

Lastly, the second pic below, what is that fuse holder for? Can someone explain what it's for and why the 3 wires but only 2 are connected? There are 2 black, 1 red. One of the blacks doesn't go to anything, is that for a ground wire to something?

Thanks for help.

First, I'm guessing the previous owner installed the master switch because he didn't want to go thru the trouble or expense of figuring out what is draining the battery. When you purchase a multimeter, make sure it has an audible beep for checking continuity. If you can grasp what a circuit is, you can use a multimeter. Voltage is checked with power on. Continuity is checked with power off. A basic circuit on your boat will be  Battery + >Fuse(circuit protection)>Switch>Load. The other side of the load is connected to the - side of the battery or a - terminal block located somewhere in the boat. To confuse you even more, some of your circuits have multiple switches and/or switches with multiple functions.

The onboard charger is NOT part of the 12v circuit. If it is not working, there may or may not be fuses on the leads. With the charger plugged in to your garage outlet and, you should be reading between 13-15vdc across the leads (ring terminals).

As far as checking loads (pumps lights etc.) If you have voltage at the load and it does not work, the load is bad. If there is no voltage at the load, you will need to determine where the voltage dropped out. A fuse? A switch? A broken wire? More often than not corrosion is the culprit with boat power issues.

IS your battery any good? Something you may want to consider is rewiring the entire boat. They make marine control centers which could simplify things.