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Color wiring diagram

Discussion in 'Electrical & Audio' started by luna negra, Jan 12, 2020.

  1. luna negra

    luna negra Junior Member

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    luna
    Truck Year:
    1979
    Truck Model:
    Jimmy
    Engine Size:
    305
    Anybody have a colored wiring diagram for a squarebody (1979 K5) where the diagram matches the actual wire colors? I've got a black/white copy and but haven't been able to find one in color like this. For me, these are so much easier to trace things around.

    Have a starter that sometimes stays engaged after releasing the key so I suppose it's the solenoid or switch but want to see how it's supposed to be wired before tearing into it. Thanks!
     
  2. chengny

    chengny Full Access Member

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    Truck Model:
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    Engine Size:
    350/5.7

    The first thing I would check is the condition of teeth on both the ring gear and pinion - but mainly the ring gear. Over the years, some of the teeth on the ring gear may have gotten banged up. This can cause the pinion gear to stay engaged with the RG - even if the solenoid plunger return spring is trying to retract the pinion.

    If that is the problem, the ring gear will generally have a few messed up teeth that are confined to a small area of the total circumference. That is why it only happens occasionally

    Just drop the starter. First look at the condition of the drive pinion. If it looks okay, rotate the engine and inspect all the RG teeth.

    You can view the teeth through the starter mounting opening, but the process goes a lot faster if you drop the flex pate dust cover:

    jammed 350 011.jpg

    How you rotate the engine is up to you, but I just clamp a pair of Vise-Grips on to the flex plate and jack it over. It rotates much easier if you pull a few spark plugs.
     
    shiftpro likes this.
  3. DanMcG

    DanMcG Supporting Member Supporting Member

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    I recently bought a colored wiring diagram from Classic Car Wiring. https://www.classiccarwiring.com/chevytruck/
    I won't get around to comparing it to the actual wiring in the 78 till spring to tell ya if it's accurate or not.
     
  4. luna negra

    luna negra Junior Member

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    Thanks for the tips. I definitely found some of the problems when I dropped the starter, like battery cable burned on manifold, copper posts loose on the solenoid and a ton of dirt and crud packed in the starter and bell housing. Previous owner obviously ran this thing a long time with the inspection cover off. One thing that does confuse me is that there are 3 separate wires and the positive battery cable attached to the main solenoid post. I would have only guessed one wire from the switch and the positive battery cable. Haven't looked at a wiring diagram yet but does this sound normal?
     
  5. DanMcG

    DanMcG Supporting Member Supporting Member

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    Engine Size:
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    I think it should be 2 wires. A red to the junction block on the firewall, and a purple to the neutral safety switch under the dash.
     
  6. chengny

    chengny Full Access Member

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    Three leads to the "B" terminal - one BLK from the battery positive and 2 RED's on the system. Also one PPL to the "S" terminal from the ignition switch:

    Copy of eng.JPG
     
  7. luna negra

    luna negra Junior Member

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    Thanks. Will try to get it sorted out this weekend.
     

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