Re: wire i dont know what it is...
You have a major mess to straighten out. The things you need to understand are these:
1) The dual battery switch is wired wrong. Very wrong. Here is a diagram of how it should be connected. Note that ONLY the large battery cables are shown. I'll get to how the house stuff should be connected later. The diagram also shows an outboard but it makes no difference for an I/O unless the switch includes a field disconnect function. The way your system is connected you do not have the versatility the switch provides and I certainly can't tell what the wiring is or where it goes. Only you can diagram that. My suggestion is to pull everything off the batteries and the switch and start with the diagram below. We will build from that.
2) Instruments are NOT powered from the fuse panel nor is the ignition switch fed from the fuse panel. 12 volts and ground pass up the engine harness from the engine to console and throttle/shift box and the ignition switch (no ground on the ignition switch). When the key is turned on, the gauges get power from the "I" terminal on the switch.
3) The big wire on the fuse panel shold be the +12 volt feed INTO the panel. There should be another equal zize black wire (ground) either on the ground bus on the panel or at a separate ground point near the panel. Here is where you need to pay attention. Every accessory on the boat (that means the big red wire on the fuse panel) should be fed by the COM terminal on the dual battery switch. It makes no sense to wire this to the house battery and have the engine wired to the start battery with only the charge wire hooked to the COM terminal. You lose the ability to start the engine from the house battery or to run accessories from the start battery if you have to. Use the switch as it was intended.
4) The only thing you need to wire directly to the battery with the largest capacity (normally the deep cycle house battery) is an automatic bilge pump so it could operate with the batteries turned off. Digest this info and see if it makes sense. But start with a clean slate. Your gauges going njuts are definitely due to a reversed polarity an "S" terminal wiring ssue, and/or a 24 volts situation due to improper wiring. As I said, you have a very badly wired boat. Start over at the batteries and the switch as that's where most of the issue likely is. Then check the back side of the gauges to see if anything was mucked with back there. It should be obvious. Properly connected, you should be able to start the engine from BAT 1, Both or BAT 2, operate accessories from BAT 1, Both or BAT 2 and charge BAT 1, BOTH or BAT 2 depending on how the switch is set. Maximum versatility.