Gas Gauge Wiring

[69Ford]

Wiring my truck back to original and just ordered a used fuel tank switch and harness. Wondering if someone could tell me what the three black wires are for the diagram only
shows the orange and two green. Thanks

[69Ford]

Did a lot of time researching wiring diagrams. Relized that the standard wiring harness has one wire coming of the gauge going into a connection and coming out as two wires. One of the
two goes to the fuel tank sending unit on tank behind seat. The other through the fire wall and is just left there. My thinking is they did this so you could have a choice which tank to have
the gauge work off. but you could not have both hooked up at the same time becouse the standard harness has the wires connected together. "no switch" I'm trying to make this truck as
close to stock as possible. Without splices. Could this truck have came this way only reading one tank. How can i tell if the AUX tank was added later. Does not look like it to me. I know lots to read. I hope I make sense. The diagram I posted above is for a switch harness which I do not have.

[colnago]

That sounds right, as far as the two wires going to the switch, then one wire going from the switch to the gauge. I thought they were supposed to be orange, though. I _thought_ all the black wires basically went to ground/chassis.

Do you have a valve for tank selection under the seat? Where does the filler for the aux tank go? My '67 CS has the aux tank fed from a filler in the front of the bed, then a cover for the filler tube in the bed itself. If you have that, it was probably stock. If you have a cut-out in the body for the filler tube, it was probably aftermarket. Oddly enough, mine has both: stock aux tank on the left, aftermarket with a filler door on the right, and a three-way switch on the dash.

Joseph

[69Ford]

The switch itself has six wires three black and three color coded. The switch did not work I had to take it apart. I know now what it is all about. Just a double three pole switch. The three
color coded on the bottom which you use to divide the tanks. The three black wires on the top are not used. Sopose you could hook lights to them so you have two lights telling you
what tank you are currently using. I ordered new wire for the tanks with the original ends to replace the ones that where cut. I finally have everthing electrical working on the truck
without nasty splices. Does anybody know if the alternater wiring harness for a 1969 mustang is the same for ford truck. From pictures it looks the same. Mine works but is kinda
trashed.

[69Ford]

After thinking about it. The three extra wires on the harness Maybe used on some fords for an electric fuel valve for switching the tanks Instead of the manual one. Does anyone know?

[cjohn2000]

From what I know about my '69 f250 camper special with the factory aux. tank is that the switch under the dash switches which tank the gauge is reading. The factory harness has three black wires (unused), a orange wire ( to gauge in cluster) and a green wire w/ a redstripe, on mine this goes to the aux. tank, and a green wire which goes to the in cab tank. The unused orange wire in the main harness goes to the wire to the in cab tank. Hope this helps.

[Clunker]

I'm also trying to sort through my dual tank wiring because my gauge isn't reading correctly. I don't understand why Ford would install a switch with three black wires that don't connect to anything. Maybe it was a part that was used in an earlier vehicle, and they just decided to use what they had in stock instead of putting in a simpler switch. Thanks for posting that schematic. It really helped.