85 C10 Only head lights are working!.

Discussion in 'Electrical & Audio' started by street5, Sep 16, 2018.

  1. street5

    street5 Junior Member

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    Joined:
    Feb 12, 2016
    Location:
    Nevada
    First Name:
    Stephen
    Truck Year:
    1985
    Truck Model:
    C10
    Engine Size:
    350
    I do not have any interior and reverse lights, my parking and tail lights only work when I have the head lights on high beam. Also when I have the head lights on high beam my interior light under the dash comes on. I have replaced all fuses, circuit breakers and head light switch with no luck. Any ideas would be great.
     
  2. Charlie

    Charlie Full Access Member

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    Joined:
    Aug 2, 2017
    Location:
    Euless, Texas
    First Name:
    Don
    Truck Year:
    1974
    Truck Model:
    Cheyenne 10 LWB
    Engine Size:
    350/TH350/AC/4 BBL Quadrajet
    :welcome:
     
  3. 75gmck25

    75gmck25 Full Access Member

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    Joined:
    Oct 13, 2016
    Location:
    VA
    First Name:
    Bruce
    Truck Year:
    1975
    Truck Model:
    K25
    Engine Size:
    5.7
    Check all the ground wires. IIRC, there should be:

    - Very important - Instrument panel ground, black wire up under the dash, often grounded to the emergency brake bracket
    - Front Lighting harness - black ground wires on each side of the engine compartment on the radiator support. Passenger side wire should also ground to the battery negative.
    - Battery ground (large wire) from the battery to the alternator mounting bracket
    - Engine ground from block to frame on passenger side, usually a flat braided wire
    - Engine ground from block to firewall on passenger side, should be a smaller sized braided wire
    - Ground for rear lighting, in back under the bumper - large gauge white wire coming out of lighting harness
    - Each tail light and parking light is also grounded, usually with a white wire. Bad ground will usually only affect one bulb, or in the front it may make turn signals flash incorrectly

    Interior lights coming on at the wrong time is a definite grounding problem. They work differently because they have constant 12 volts power, but are turned on when grounded through the door switches or by rotating the headlight switch. This is the opposite of most other bulbs and devices, which are always grounded, and then turned on by applying power.

    Bruce
     
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  4. Tom corsi

    Tom corsi Junior Member

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    Joined:
    Oct 1, 2018
    Location:
    Plant city fl
    First Name:
    Thomas
    Truck Year:
    1986
    Truck Model:
    C30 3+3
    Engine Size:
    350
    What did you figure out street5 I have the exact same issue
     

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