Dome Light problem

Discussion in 'Audio + Electronics' started by Biomeche, Apr 27, 2020.

  1. Biomeche

    Biomeche Newbie

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    Hi all,

    I have a 1997 C3500 crew cab with a 6.5L, with the dreaded dome light and cargo light issue. I have done some trouble shooting.....

    The cargo light switch has power at the orange wire, the switch is working correctly, and has good ground at the cargo light (the interior white ground wire), the brake lights do work, there is no continuity between the blue/white wire between the switch and the light. I can get the cargo light to go on by jumping 12V into the blue and white wire at the cargo light.

    The same is true with the dome lights, I have a good ground, I have 12 V at the orange wire under the dash, the orange wire does not have continuity with the wire under the dash. I can get the lights to come on by jumping 12V at the contact with the orange wire at the lights. All door switches are working appropriatly, and all bulbs are working.

    .....it seems that both the orange and blue/white wire have been cut somewhere. I have not pulled the trim down to look at the wires, is there a common place where both these wires can be cut? I'm not blowing fuses, so i dont think it shorting out. I'd rather not pull down all the trim, it is somewhat brittle

    thanks in advance
     
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  2. AK49BWL

    AK49BWL GMT400 Forever!

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    That blue wire, as I recall, runs down the length of the driver side step, under the plastic.. If it's been cut by someone, that's my best guess where it'd be cut. Or someone was screwing around under the dash. The ground at the cargo light switch is only for the backlight in the switch and has nothing to do with the cargo light itself. The dome lights should have constant power, and the ground side is switched by the lighting control module mounted to the steering column under the dash. The cargo light is also grounded by the lighting module; the dome lights have to be on for the cargo light to work. I'm guessing the dome lights don't come on when you push the dimmer knob all the way up? That would supply a direct ground, bypassing the module.

    Just reread that, you aren't getting the constant power at the lights.. Again, under the dash or along the driver step.. Otherwise you're taking down the trim, there's no other way to get to the wiring in the back.
     
    Last edited: Apr 27, 2020
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  3. Biomeche

    Biomeche Newbie

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    thanks a million, will strt there
     
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  4. Dathan99

    Dathan99 Newbie

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    Could you post a picture of where Exactly exactly the lightning control module is? I know you mentioned it’s under the steering wheel dash but I just can’t seem to see it.
     
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