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Wiring Diagram Help

Discussion in 'Chevy Trucks' started by bowtie726, Dec 29, 2005.

  1. bowtie726

    bowtie726 Junior Member
    Messages: 15

    :help: Alright, this has been tearing my brain apart all day. The following wiring diagram is for dual fuel tanks on a who knows what year chevy. I've got a 74...(well, mostly 74...I think it's got parts on it from 73 to 80something) But it has one of these "fuel tank selector valves on it, but it isn't wire up. Now, the wires that go inside the cab are not on this diagram, but on the second diagram. In other words instead of the dk grn and lt grn wires shown in use with the "fuel tank selector valve" I have 4 wires, a lt blu, tan, lt grn, and tan/w. I understand how the second diagram is supposed to work, and everything in the cab is set up just that way... But how does that "fuel tank selector valve" work? It shows switches inside, but no coils that indicate a magnetic type switching....I'm very confused by how that deal is supposed to work. I know how to read wiring diagrams, but either I'm missing something here, or the diagram isn't showing something because unless there's a manual switch on that damn "selector valve" which by the way is located under the truck, I don't understand how it switches anything. And what is that circle with the "A" in it? It's labled "PM Valve" but I've never heard of one of those...:dizzy: I know all I should do is go get the solenoid shown the the second digram, but shouldn't I be able to wire that selector valve to just switch fuel line like the solenoid would?

    wiring fuel tanks2.GIF

  2. 75gmck25

    75gmck25 Senior Member
    Messages: 119

    tankwiring3.gif is a scan of the '74 Chevy/GMC wiring diagram for the factory aux tank option.

    I'm not sure what year the other diagram is from, but I think I've seen a similar setup on trucks in the junkyard. On some trucks I have seen only two wires coming through the firewall, but never crawled underneath to see how the under-truck valve was wired.