Are the chart plotter and sonar still on that same switch/circuit?? If so, do they power up??
How are you measuring voltage at the radio?? With a light bulb circuit tester or a Multi-meter?
If it was working before the switch was replaced, I would look for a bad splice, shorted or frayed wire? Does the radio work if the switch is taken out of the circuit and you jump the lead into and the wire out of the switch together??? This would indicate the internal resistance of the switch is causing a voltage drop that is causing your problem.
Can you remove the panel's screws and pull the panel forward to gain access? As I remember, the toggle part of the switch can be removed by gently prying/opening up the the pivot point. Then, the body of the switch is held in place by a couple of ears on either side. Depress those and the switch can be removed from the panel.
Or,.....have the dealer come fix the problem his work created?
