Brian, not being there to check with a meter....I would guess that 'C' is for the Utility and scene light. C to 3. The wire still atached should be the +12dc. On my switch for the lights the utility and scene lights at connected together just outside the switch.
Would have to guess that the other two wires go to the other switch, the water pump. One should be +12v and the goes to the pump. If you have a meter to check for voltage that would be the best thing to to.
I would conncect the lights first and if it works...the other two goes to the pump. Without a meter to determine the +12v, and if the switch isn't marked as such...connect the wires to the switch in the off position and and pump shouldn't run, as the switch is an on/off...I would try A to 1 and B to 2.
Agree with DriVer on the connector.
workhorse