TruckLite sells a product designed exactly for what you want. "CORROSION-FREE CONNECTIONS................
Damage from external corrosives is among leading causes of lamp and harness failure, and can be prevented with proper insulation of your electrical connections. Truck-Lite's NYK-77® corrosion preventive compound is designed for periodic use on electrical contacts, switches & junction boxes and other connections."
A grease designed to inhibit corrosion. It's made for their terminal connections on all their lights. You can buy it in a small tube from any NAPA store. PN 97944 or 97944-1.
The tip of the tube has to be opened up before you use it. Don't use a knife to open it. Use a 3/32" drill bit. Put your connector in one hand, and the tube in the other. Hold the tube tight against the connector and squeeze while you're sliding the tip over the holes. The grease will fill in the terminal holes, creating a corrosion proof connection. Connect your electronic unit a few times, and then refill the holes with grease. The grease will transfer to the male pins on the unit.
Use this on EVERY Electrical connection on your boat. Use it inside any crimp connections, too. If you do it right, you'll never see green again. :wink:
Inspect the terminals peiodically, and regrease them when it looks like they need it.