fuel guage reads past full all the time

[R72K5]

yeah nothing works, guage reads past full no matter what i do or what i jump, etc, it has never moved at all yet, still, ive tried everything,


i know where all the wires go to, they all go to the dash switch

in this harness and under the truck is two tan wires(one striped and other solid) and a green and a blue, no extra wires, no hidden other ones, nothing, thats it, its really VERY basic, straight from switch valve assembly and tanks up to the dash switch, nothing else


i need to find out where the green wire is supposed to go under there and also the white striped tan wire



the pink just runs from the dash switch to the fuse panel

GM did not run a wire from the dash switch to the guage ?

how can the guage ever read anything if there isnt this wire ?

i dont understand it, something is missing,

there has to be

the blue and solid tan wire are the tank sender wires, but they dont go to the guage, they go to the dash switch, and none of the dash switch wires go to the guage

any guage wires it has are in the main cab harness only

this is freaking wierd

i am so beyond lost, it makes no sense whatsoever

thanks

 

[dyeager535]

Obviously something missing.

Have to find the tank sending unit wires, follow them "forward", or start at the cluster and work your way to the tanks from that end. Either one is going to be in place and obvious, figuring out where they go, less so.

 

[R72K5]

but theres nothing cut or odd looking under the dash anywhere, cept for radio stuff of course

no loose ends or anything cut, or anything else,
actually very nice shape wiring,
most all the trucks ive ever had have actually had real nice shape unmolested cab harnesses, not limited to this 77

so i dunno

im at a loss

no diagram for these old suckers, and hum no one seems to know anything about the dual tank harness of the first years of the second gen rigs,

...


damn

thanks so far

 

[dyeager535]

Got the cluster out? Figure out which wire on the cluster connector is the fuel gauge one, and find it under the truck.