No Headlights

Discussion in 'Lighting & Illumination' started by Chewy37, Feb 12, 2017.

  1. Chewy37

    Chewy37 New Member

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    2001 Chevy Silverado 2500 HD 8.1 Allison Crewcab

    Started it up the other night no headlights, here's what I've checked so far:

    Checked the bulbs
    Fuses and relays in all 3 fuse box locations
    Connections above gas and Brake peddles
    Replaced the switch on the dash
    The Blinker/Highbeam/Windshield wiper arm was replaced a few years ago and is working
    Pulled the fuse box out under the hood, there were some acorns underneath but no wires seemed to be eaten.

    Is the ground connected to the bumper? If so which side?

    Thank You for your help
     
  2. John Clark

    John Clark GMFS Member

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    Do you have a test light? The first thing I'd do is download the wiring diagram:

    http://www.revbase.com/BBBMotor/Wd/DownloadPdf?id=70268

    Then, based on the diagram, I'd start testing for voltage. I'd start by turning on the headlights and checking for 12 volts on the left and right headlamp fuses in the underhood junction box. Each fuse has two small contact pads on the top that you can touch the probe of a test light (or voltmeter but test light is better) to in order to check for voltage on both sides of the fuse. If using a test light, put the aligator clip of the test light on a good ground and then touch the probe to each contact pad on the top of the fuse. If using a voltmeter, consider going to the auto parts store and buying a test light as it's a much better diagnostic tool than the volt meter. If you insist on using a volt meter then put the black lead on a good ground and touch the red to the top of the fuse contact pads. If there's 12 volts on one pad and not the other then the fuse is bad. If there is no voltage on either side then relay is not closing and we can troubleshoot the relay from there. If there is voltage on each pad of the two headlamp fuses then we know power is getting to the headlights and the problem will be in the ground.

    Do those tests on the fuses and post back. That will determine the direction we go.
     
  3. Irishboy02

    Irishboy02 GMFS Member

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    Do you have tails and parking lights? Or is the whole circuit out?

    Sent from my LG-D800 using Tapatalk
     
  4. Chewy37

    Chewy37 New Member

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    Thanks John, will be working on it again this afternoon I will post back.
     
  5. Chewy37

    Chewy37 New Member

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    Yes have tails and parking lights
     
  6. Slim

    Slim Jake

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  7. SkyHigh98

    SkyHigh98 Typical Smart-Ass

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  8. Chewy21

    Chewy21 Wookie on the Beat

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    WOT
     
  9. Chewy37

    Chewy37 New Member

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    http://www.revbase.com/BBBMotor/Wd/DownloadPdf?id=70268

    Then, based on the diagram, I'd start testing for voltage. I'd start by turning on the headlights and checking for 12 volts on the left and right headlamp fuses in the underhood junction box. Each fuse has two small contact pads on the top that you can touch the probe of a test light (or voltmeter but test light is better) to in order to check for voltage on both sides of the fuse. If using a test light, put the aligator clip of the test light on a good ground and then touch the probe to each contact pad on the top of the fuse. If using a voltmeter, consider going to the auto parts store and buying a test light as it's a much better diagnostic tool than the volt meter. If you insist on using a volt meter then put the black lead on a good ground and touch the red to the top of the fuse contact pads. If there's 12 volts on one pad and not the other then the fuse is bad. If there is no voltage on either side then relay is not closing and we can troubleshoot the relay from there. If there is voltage on each pad of the two headlamp fuses then we know power is getting to the headlights and the problem will be in the ground.

    Do those tests on the fuses and post back. That will determine the direction we go.[/QUOTE]
     
  10. Chewy37

    Chewy37 New Member

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    Found two wires that were burned in this cluster which connects here(next pic) at the base of the steering column. The brown wire is #12 and yellow/red is #13. Searching for a schematic to show where it leads, any help would be great.


    [​IMG]


    [​IMG]
     
  11. John Clark

    John Clark GMFS Member

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    Your pics aren't showing. Burned wires are not good but whatever it is doesn't sound like it's associated with the headlights. Unless the diagram is wrong (it's an OEM diagram) I don't see any brown or yellow/red wires in the headlight system. There is, however, a yellow wire and a purple wire that goes through the high beam/low beam switch. If the yellow wire were broken (or burned) somewhere that would prevent the low beams from working. If the high beams work that means the purple wire is good. Also, high resistance in the low beam switch or the connector (bascially a bad switch or loose connection) could possibly cause the yellow wire to burn and then the low beams wouldn't work.

    I was hoping you'd test for voltage at the two fuses I mentioned. If there's voltage there and at the headlights themselves then we know it's a ground side issue. The high beam/low beam switch is in the ground side of the circuit.
     
    Last edited: Feb 15, 2017
  12. Chewy37

    Chewy37 New Member

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    IMG_1041.JPG IMG_1044.JPG IMG_1041.JPG
     
  13. John Clark

    John Clark GMFS Member

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    Ok. That looks like the column switch harness. It is for the turn signals, wipers, hazard lights, and head light dimming. The #12 wire is the wire going directly to the headlight low beam bulbs. The #13 wire is the ground for the headlights. The low beam switch is in between those two wires. It matches #12 and #13 on the diagram I've already posted.

    My best guess is that's an aftermarket switch which doesn't have the OEM wire colors and is not of the quality of OEM (probably why it burned.) That's definitely your problem and you need to replace the entire switch assembly with the harness. I would recommend getting an AC Delco switch. They are more money than the cheaper aftermarkets but you increase the risk of this kind of thing when you go aftermarket.

    http://www.rockauto.com/en/catalog/...,electrical-switch+&+relay,dimmer+switch,4340

    Are the pins on the other side of the connector OK? They look a little black. If those are not cleaned up a new switch might do the same thing due to increased resistance at the pins. Increased resistance equals heat. Heat equals burned connectors. It's possible the connectors in the aftermarket switch were too loose to begin with.
     
    Last edited: Feb 15, 2017
    Chewy37 likes this.
  14. Chewy37

    Chewy37 New Member

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    Hi John,
    The switch was replaced about 4 or 5 years ago, leaning towards the connection being loose as the cause of the problem like you said. Just bought a new one direct from a Chevy dealership. I will update when it's in, thanks for all of your help
     

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