86 k15 mystery wires

[gcochran223]

anyone have a idea what these may be for? i am hoping they are for my temp sensor that goes into the head since i am unable to find the plug for it. 86 k15 a/c truck, was a 305 auto from factory.

[gcochran223]

here are some more wires that involve my fuel system. i eliminated the dual tanks and went with just the single tank on the passanger side. i installed a new tank and sender.my sender is grounded to the frame yet my fuel gauge is pegged to the far right past the full mark. what is the harness looking wire? it has a red that goes onto my new tank but i dont recall what it is connected too. and what are the caps for that are on the right side by the main wire trunkline?

[bake74]

     In your first pic, where do the wires come from and go, is one end not hooked up ?
     Second pic,  same thing, do you know where those wires go ?  I am not a 81 + truck guy, I have all pre 81 trucks.  So someone else might have to chime in.
     Third pic, those caps look like they were suppose to be on the sending unit.  When you eliminated your second tank, did you make sure to disconnect the second tank wiring ?  This might be why your fuel gauge is pegged, if it is reading false voltage, or a short somewhere.

[gcochran223]

-the first set of wires come out of the main harness against the fire wall, the only obvious wires i recognize is the alternator wires it is ran with. they are a light blue and tan colored wires that were cut.

-the second set is on the passenger side of the truck where the old fuel tank used to be. they are just hanging their and then run to the driver side then to the front of the truck in the wire loom.

-the third set is on the driver side where that fuel tank used to be.

with disconnecting the wiring i did not disconnect anything. both tanks were junk and i cant recall what i disconnected, it was 2 years ago. i just dropped both tanks and added all new on the passenger side.

[gcochran223]

if I'm reading this diagram right the first wires could be

tan- oil pressure sender? but my oil pressure is connected and working

lt blue-choke heater from oil pressure switch?

i guess another question is I'm trying to connect my temp sensor, is this just a one wire connection that plugs into the head?

[gcochran223]

-so for the second pic via this diagram, that red wire must be pink. what does this pink wire do? its not connected at the moment but via the diagram it sends some signal up front .


-and that 6 connection plug thats on mine now, i do not see on this diagram.

[gcochran223]

alright digging around this sunday afternoon i found out that for my temp sender i need to find the dk green wire coming out of the fire wall. the other two wires are oblivious prolly a/c garbage.

the second is for the fuel tank selector valve

the third is for fuel sender wires that are no longer used.

how does the fuel tank get signal or information on how much is in the tank the pink wire? but the pink wire goes from my new sender to that selector valve which is no longer used.

[bake74]

      Yes, your temp sensor should be 1 wire that hooks up. 
      The hardest part about wiring is coming along after someone else and trying to figure out what they did.  Sometimes at work on machines, the wiring has been so much "spider webbed" as I affectingly call it, that is takes less time to rip everything out and start over.  What I am trying to say is, it is hard for us sometimes to follow you because we can not see the whole picture.
      If it looks like there are extra wires, or wires that do not coincide with the diagrams colors then they are probably add on's in which case they might have replaced a wire or been routed instead of a wire.
     As far as the 6 prong wire loom plug you are talking about, since you said it is on the passenger side and drivers side by where the gas tanks used to be I would venture a guess and say they had something to do with the gas tanks.  But at this point I would have to investigate more to figure it out.  Maybe someone with 81+ experience will chime in.

     See if this diagram matches any wire colors you are talking about near where the fuel tanks were.

[gcochran223]

yeah tomorrow if its not raining im going to try and find the temp sensor wire and splice that pink through to the cluster.