If you have a Volt-Ohm meter, set it to Ohms and put one test lead on each side of the switch with the wires still removed. The meter should either read 0 or near full scale. Turn the switch to the other position and check it again with the meter. The meter should read 0 if it read full scale before or full scale if it read 0 before. If this is the case, the switch is working properly and there is a wiring issue. While you have the wires off of the switch, check each wire for ground or current using the following procedure:
Try to locate a suitable ground near the switch, a piece of the coach frame, the grounding lug on a outlet, etc. With the Volt-Ohm meter still set to ohm's, put one meter lead on a ground or a wire that goes to known ground and the other meter lead on one of the wires to the switch. If the meter reads 0, you have a wire that is grounded. Then check the other wire that goes to the switch for the same condition. If you get a very high ohm reading on one wire or the other, change the meter to DC volts. Put the black meter lead on a known ground and put the red meter lead on one of the wires. It should either read 0 or about 12-13 volts. If it reads 12-13 volts you know that wire is 'hot'. Check the other wire, and see if it is hot or if it reads 0. In a normal situation where the hot wire is switched, you would have a 12 volt hot wire coming into the switch, the switch would make or break the connection to the other wire so that when the switch is off, the wire going into one side of the switch has 12 volts and the other does not. When the switch is on, both wires would show 12 volts when the volt meter black wire is connected to a ground.
If the switch is breaking the ground (not typical), then one side would show 0 ohms of resistance when the red meter lead is attached to it and the black meter lead is attached to a known ground and the other side would not with the switch turned off.
There is another possibility, although it is not used often for water pumps, and that is a bad relay. If there is a relay in the circuit, the switch just sends a trigger signal to the relay to close and send power to the pump. I am not aware of Newell using relays on the water pumps but a relay hung to the closed position would certainly exhibit the symptoms you are experiencing since a signal would not be needed to send power to the water pump and the only way to turn the pump off would be to remove power from the relay.
|