Jim Cooper
Senior Member
Purchased a new boat with dual tanks & one fuel gauge; wiring was unfinished. I purchased an on-off-on single pole, double throw, lighted rocker switch to be able to read each fuel tank on the one gauge. The switch has 4 terminals, one each for the sender wires, one for the gauge feed and one for the light neg. ground (the light positive is supplied from the gauge feed) Connections are straight forward so I know I have the wires connected to each terminal correctly.
Problem: when completely wired, I don't believe I am seeing true readings so I tried a couple scenarios and came up with the following -
Scenario 1 eliminated the switch completely, connected each sender wire independently to the gauge feed. READINGS = TANK1 7/8; TANK2 3/8
Scenario 2 installed switch, connected gauge feed and only one sender independently, did not connect light ground. READINGS = TANK1 7/8; TANK2 3/8
Scenario 3 installed switch, connected gauge feed and both sender wires, did not connect light ground. READINGS = TANK1 FULL; TANK2 3/4
Scenario 4 installed switch, connected gauge feed and both sender wires, light ground wire connected. READINGS = TANK1 PAST FULL; TANK2 7/8
My observations are the reading through the switch only matched the reading without the use of the switch when only one sender wire was connected. My other observation is the readings appear to increase each time an additional wire is connected to the switch.
Any ideas what is going on? The switch manufacture already replaced the switch once and the second device produces the same results.
Problem: when completely wired, I don't believe I am seeing true readings so I tried a couple scenarios and came up with the following -
Scenario 1 eliminated the switch completely, connected each sender wire independently to the gauge feed. READINGS = TANK1 7/8; TANK2 3/8
Scenario 2 installed switch, connected gauge feed and only one sender independently, did not connect light ground. READINGS = TANK1 7/8; TANK2 3/8
Scenario 3 installed switch, connected gauge feed and both sender wires, did not connect light ground. READINGS = TANK1 FULL; TANK2 3/4
Scenario 4 installed switch, connected gauge feed and both sender wires, light ground wire connected. READINGS = TANK1 PAST FULL; TANK2 7/8
My observations are the reading through the switch only matched the reading without the use of the switch when only one sender wire was connected. My other observation is the readings appear to increase each time an additional wire is connected to the switch.
Any ideas what is going on? The switch manufacture already replaced the switch once and the second device produces the same results.