All of the gauges don't work

I have 2004 Ski Nautique Limited that all of a sudden all of the sudden the gauges didn't work. I checked the Serial Bus owners manual and started checking the voltages. What I first checked are 2 voltages one is a red wire that has 12 volts always on and the other was a purple wire that has switched 12 volts where 12 volts is present once the key pad turns the engine power to on. Both of these wires terminate at the Serial Bus. I cannot locate the Serial Bus and I do not know where the Red wire originates from. Does anyone have a wiring diagram and where is the Serial Bus located?
Thanks Willy

Thanks, I had Nautique Service Center look at the problem and the gateway was reversed (couldn't see the fuses) all that was needed was the Gateway to be re-positioned and reset the fuse button.