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Brights turning on by themselves? Anyone had this problem?

Discussion in '1st Gen. Tacomas (1995-2004)' started by Jboogie415, Nov 14, 2023.

  1. Nov 14, 2023 at 5:28 AM
    #1
    Jboogie415

    Jboogie415 [OP] Member

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    As the title says,have a weird problem that I’m hoping is common and you gents have a fix for ,like you do for everything else ;) came out to my truck at 5am this morning,and my brights were on. I know for sure they were not on when I went inside last night. This has happened multiple times now, only one time it drained the battery.which makes me think they are turning on and off themselves at night, I have a short? Thoughts? Actions? I’m an electrician so I know my way around a multimeter ,luckily. Kind of just asking here to see if it’s something to do with something the previous owner did when putting in an aftermarket radio or it’s a common thing. Thanks in advance.
     
  2. Nov 14, 2023 at 11:06 AM
    #2
    Andy01DblCabTacoma

    Andy01DblCabTacoma Well-Known Member

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    Not common. Start with a visual inspection to see if the PO installed anything aftermarket in the engine bay- looking specifically at the head light assemblies and wiring harnesses. Follow them back to their sources. OEM stuff will just be a connector to the bulb and disappear into a loom pretty quickly. If there is anything else it's probably aftermarket. If it all looks OEM, then you'll be looking for any damage to the wiring, going all the way back to the switch on the light stock in the cab. Should be easy to pin point the issue with a multimeter. I don't have '99 wiring diagrams, but maybe @TnShooter does.
     
  3. Nov 14, 2023 at 1:18 PM
    #3
    TnShooter

    TnShooter The TacomaWorld Stray

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    The headlight fuses can not come on unless the relay is closed.
    The dimmer switch grounds the relay to close the circuit. I'd use a test and play around with the headlight switch and wires until the the fuse get power.
    Wiggle, and pull in the wires. same with the headlight switch.

    I included the diagram below.Screenshot 2023-11-14 161252.png
     
    Andy01DblCabTacoma likes this.
  4. Nov 14, 2023 at 1:27 PM
    #4
    Andy01DblCabTacoma

    Andy01DblCabTacoma Well-Known Member

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    I'd be willing to bet that if his lights are coming on without the key in the ignition, that there is an aftermarket wiring kit straight to the battery that's gone bad / poorly installed.
     
    TnShooter[QUOTED] likes this.
  5. Nov 14, 2023 at 9:18 PM
    #5
    Jboogie415

    Jboogie415 [OP] Member

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    You guys are awesome ! Thank you for the advice. I’ll dig into it this weekend.
     
    TnShooter likes this.

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