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Lost my interior lights

Discussion in 'GM Electrical Tech' started by PantheraUncia, Dec 18, 2012.

  1. PantheraUncia

    PantheraUncia Active Member 2 Years 1000 Posts

    In the process of replacing a light in the truck, all my interior lights stopped working. To be clear:

    My Instrument cluster lights up and works, the radio, the AC control, work also. My turn signals are fine but seem to be running at a lower power, the head lights and turn signals work.

    What does not work is the map and dome lights, and then my third brake light with the cargo lamp, and the courtesy lights in the door panels.

    I checked all my fuses with a mult-meter and they all beep out fine showing the signal is going through. I made no changes to any grounds and confirmed that my grounds are fine.

    I heard about some sort of switch in the doors that might trigger the courtesy lights? not sure about that and never touched it.

    I am kinda lost at this point.
  2. Sierraowner5.3

    Sierraowner5.3 Rockstar 3 Years 1000 Posts

    door switch or a grounded wire some place.....

    thats just my guess tho.

    Alex
  3. Pikey

    Pikey Moderator Staff Member 2 Years ROTM Winner 1000 Posts

    The switch that controls the lights is in the door latch mechanism. I have often seen door pins failing and causing the door to sag slightly. Eventually the latch mechanism gets beat up enough that the interior light switch no longer works. Do they turn on when you open your passenger door? Does the third brake light not work? or just the cargo light?
  4. PantheraUncia

    PantheraUncia Active Member 2 Years 1000 Posts

    I am going to have to double check when I get home....
  5. RayVoy

    RayVoy Well-Known Member 2 Years 1000 Posts

    If this happen while the new light was being installed, it must be a problem caused by the install.

    99% of the time it is a blown fuse (or two).

    Yes, it could be some other part of the circuit (wire, switch, burnt ground); but, the fuses are there to prevent damage. If the circuit was protected by the correct fuse size, nothing but the fuse should be bad.

    Unless, you accidentally cut a wire while doing the install.

    Is it possible that you accidentally turned off the interior lights?

    What light were you trying to install?
  6. ChevyFan

    ChevyFan Administrator Staff Member 5+ Years 5000 Posts

    Wait, they were working and one went out? Then you replaced that it now nothing works? What is the light that you were trying to change/
  7. PantheraUncia

    PantheraUncia Active Member 2 Years 1000 Posts

    I was installing my new LED under hood work light to the factory under hood work light harness that came with the truck (My model/year has a under hood work light).

    What does not work is:
    • the map
    • dome light
    • third brake light with the cargo lamp (Cargo light not working) brake light works
    • Courtesy lights in the door panels
    • Glove box light
    • Ashe tray light




    • None of them look burned out, no smell of an electrical burn, etc
    • No fuses are knocked out (I checked them with a Multimeter)
    • The door lock clamps/motors/ etc were replaced 6 months ago when I fixed my automatic door locks.

  8. RayVoy

    RayVoy Well-Known Member 2 Years 1000 Posts

    Ok, so I'll conclude that (to the best of your knowledge) everything worked before you raised the hood.

    Logic, and a whole lot of experience, tells me that that if you were working on it "hot" (battery connected), the most likely culprit is a fuse (however, with the list that you provided it appears that more than one fuse should be involved).
    If you disconnected the battery, then if must be a broken/cut wire, or a wire left disconnected when the battery was reconnected.

    Looking at the list, I would suggest you have 3 circuits that are not working.

    - the 3rd brake light - if it is the brake part (and not the cargo light), I suspect this was not working before you started the install, check the bulb

    - map lights, glove box light, under hood light and all lights that can not be dimmed, this must be something common to all lights - it must be power, or ground.

    - dome lights, dash lights, cargo lights and all lamps that can be dimmed. This, again, must be something common to all, look at power, ground, or the rheostat that dims the lamps.

    Ok, there is one more part that is common to all of the lights (except, perhaps, the 3rd brake light), and that is the Body Control Module (BCM) a lot of circuits are routed through the BCM so the BCM can monitor the load and shut off the lights when the battery voltage drops (if you leave them on when the truck is turned off).

    I don't have a wiring diagram for your truck, just going from what I know about my old truck.
  9. PantheraUncia

    PantheraUncia Active Member 2 Years 1000 Posts


    Its gotta be a ground somewhere..... I got them to come on at half brightness again (the map light). Something is shorting something out somewhere.

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