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Thread: backup lights problem

  1. #1
    Junior Member
    Join Date
    Dec 2010
    nw houston,tx

    Exclamation backup lights problem

    all lights on this truck (94 chevy 2wd vortec 4.3) work except for the back up lights and cargo lamps i checked fuse for back up fuse is good but still no power getting to the back up lamps you can im me on yahoo (chrsbrgrn) or text me ill be ******* with it 281 795 3729

  2. #2
    Senior Member chevy_girl_85's Avatar
    Join Date
    Feb 2010
    Reno, NV
    Have you checked the power feed for the backup lights at the switch on the trans? Is this an auto or manual trans?
    Live Fast, Ride Hard

  3. #3
    Forum Moderator Boudin's Avatar
    Join Date
    Jul 2009
    Central Mississippi
    More than likely, it is a ground. I have found that most of the "mysterious" electrical issues that cannot be diagnosed by the obvious (wire disconnected, fuse blown, etc) are usually caused by a bad ground connection. I am not familiar with the early 90's Chevys and their wiring setups....sorry.

  4. #4
    Senior Member
    crabtruck's Avatar
    Join Date
    Jul 2007
    Welcome to the forum chrsbrgrn. That an s10 ?
    Believe you can set an email alert for replies (?)

    You can confirm your Turn/BU fuse is really doing it's job
    by using the turn sigs. Even though the bulbs
    have checked out good for other reasons, like
    brake and haz which also use it, this is a different
    wire path at front of truck (near column).
    Do this to save time and error.

    If using turn arm makes lights blink, next step
    is check BU switch itself. Manual trans switch
    is located on top front end of trans itself.
    Auto trans switch is located on top of
    steering column shaft just as it exits the floor.
    Two plugs there, near door is BU, away is P/N.
    Both switches are using a blue wire and a green wire.

    Disconnect the plug and jump the plug wires
    with the key in Run. If lights work, then the
    switch is bad or misaligned with shift pawl.
    If not working with jumper, check for hot there.

    Doubt ground is an issue for this problem,
    check rear harness plug on frame for problems,
    especially if you have wiring for trailer.

    The wiring path starts at fuse and if AT does a
    u-turn on column to reach down to BU switch,
    then doubles back on itself to go out firewall
    behind fuses as part of bulkhead connector.
    If MT, goes out bulkhead and down to trans,
    then back thru bulkhead to again u-turn
    so it can go out same connector AT was using.
    Not likely bulkhead connector is the problem
    just so you are aware what's happening.


    Cargo lamp shares nothing with BU lights.
    Runs off CTSY fuse which is hot at all times.
    If your other door operated courtesy lights
    are working then the fuse is not the problem.
    Cargo lamps only work when other door lights do.

    Both ground and hot are fed from a plug
    at the top of the Convenience Center.
    Thats the wiring plugin panel thing below fuses.
    Believe you will find a green body plug at top
    with one Org and one Wht wire in spot labeled GRN.

    The Org wire is the hot and runs directly
    to the Cargo light switch. Output of switch
    is Org w/ a Blk marker. That wire joins with
    the Wht wire very near Conv Cntr in a plug
    with four wires.

    This set of wires travels along floor to rear of cab
    then goes up left rear of cab to roof and top lights.
    No connections on roof except to bulbs.
    You might want to double check they are good.

    That white wire from Conv Cntr to cargo lamp
    is not really a ground wire.
    Really grounding it and using cargo sw will give light.
    Don't do that.

    The Wht wire after going through some splices
    is connected to your door switches as well as
    the panel dimmer switch. Any of those three
    will provide the ground for cargo lamp to work.

    Doubt ground is an issue for this problem.
    Suggest the following order:

    Confirm other door operated lights work, keep them on.
    Turn on cargo switch. If not working:
    check green body plug is firmly connected from switch.
    If tight, then remove and jump the contacts in ConvCntr.
    If light works, switch is unplugged behind dash or bad.
    If light doesn't work, remove lens cover on back of cab
    and check lamp then check socket for hot on Org/Blk.
    (FYI Yel and Blk wires are for brake light)

    You should be able to fix these, mostly connect the dots.
    Post back and let us know what you find.

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