Your chart is right in your first post - although the common goes to the relay instead of the pump if you are using one. I ran mine for years without one until I realized how much of a voltage drop there was without the relay. Unless you live in the salt belt and are driving in the winter, it will take years before the terminals corrode on the relay or pressure switch contacts. You could use silicone dielectric grease in the plug and on the terminals if you wish.