Help! I need to know the wire color coming from the gas tank going to the dash on an 82 Chevy C10 pickup.
The truck has 2 tanks, the gas gauge doesn't work. has switch on dash. Will not use passenger side tank. I'm trying not to drop the tank, because the sending unit is impossible to get to. I want to ground out wire from sending unit to gauge and hope I can do it from under truck without getting to sending unit. And of course, eliminating the entire passenger side tank. Thanks to anyone who can help
With that dual tank setup you can do your test at the connector to the fuel tank selector valve.
These should be the wiring colors, but even if they aren't, you can just pull off that connector and provide direct ground to each terminal. One of them should make your fuel gauge read empty.
Chevy used a 0-90-ohm fuel sender and gauge. No resistance "0 ohms" = Fuel gauge reading Empty.
90 ohms = Fuel gauge reading Full.
So look at the Fuel tank selector valve. (highlighted Yellow)
The solid Pink wire from the fuel gauge is going to its connector.
If you have the Main fuel tank selected, that Pink wire to the fuel gauge is connected to the Pink/White wire that goes to the Fuel level sender in the Main fuel tank. (as shown in the diagram).
If you have the Auxiliary fuel tank selected, the internal switch moves and that Pink wire going to the fuel gauge is connected to the Pink/Black wire that goes to the Fuel level sender in the Auxiliary fuel tank.
So this connector should tell you everything you need to know.
You can Ground out the (Pink) wire going to the fuel gauge there and see if the fuel gauge goes to Empty .
You can Fill up the gas tank and either measure resistance or simply "jumper" the Pink wire terminal to the Pink/White wire terminal and see if the fuel gauge goes to Full.
Just one more thing and I'm answering a question you didn't ask.
Look at the fuel tank senders I have circled in Red.
You can see the wiring going to them from the top of the senders which I have highlighted.
But look at the bottom of those senders in the diagram.
They need a Ground and the Ground goes from the body of the sender unit to the frame.
They aren't being much help on the wiring color.
It says, BLU, or PPL, or LT GRN.
But it should be pretty easy to identify because it will be the only wire going to frame ground from the top of your fuel tank.
If this wire is broken or the connection to the frame is corroded, the fuel gauge won't work so maybe check that 1st
