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72k20Farmtruck · 03-26-2018, 02:14 AM

I just rewired mine, also a 77. It’ll blow your mind lol, GM decided to run the wire out from the switch, out the firewall, down the frame with the sending unit wires, cross the frame at the crossmember where your switching valve is mounted, and in the vicinity of the switching valve is a fusible link/connector on your gauge wire, where is continues back up the frame now on the passenger side, crossing the the top of the motor in the main loom and ends up going into the fuseblock. Have fun tracing it out, i upgraded mine to the newer style switching valve with the 6 prong connector where the sending unit signal is switched at the valve instead of at the switch.

03-26-2018, 02:14 AM	#2
72k20Farmtruck Registered User Join Date: Oct 2015 Location: Spokane, Wa Posts: 112	Re: 77 k3500 fuel gauge wire ? I just rewired mine, also a 77. It’ll blow your mind lol, GM decided to run the wire out from the switch, out the firewall, down the frame with the sending unit wires, cross the frame at the crossmember where your switching valve is mounted, and in the vicinity of the switching valve is a fusible link/connector on your gauge wire, where is continues back up the frame now on the passenger side, crossing the the top of the motor in the main loom and ends up going into the fuseblock. Have fun tracing it out, i upgraded mine to the newer style switching valve with the 6 prong connector where the sending unit signal is switched at the valve instead of at the switch.