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Right headlight keeps shutting off

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Shawn W., Feb 26, 2023.

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  1. Shawn W.

    Shawn W. Junior Member

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    I saw that there's a thread about the same issue that I'm having, but there didn't seem to be a resolution to the problem, and the thread is about a decade old, so I figure that I'd make a new thread.

    My right headlight keeps shutting off, but it'll turn back on if I flip the switch off and on. I was fine dealing with it that way, but it did it three times today within about ten minutes while I was on my home from a gas station. I didn't initially know that I had a problem until I was pulled over by a state trooper a couple of months ago, who thankfully didn't ticket me and just told me to get it fixed.

    Also, FYI, my car is a 2004 and I bought it used a little over a year and a half ago, so I'd imagine that it's had the headlights replaced at least once.

    Anyway, any thoughts on what may be causing the issue, and how it can be fixed? I took it into my mechanic and he suggested that it may be overheating, but he doesn't know for sure, and that he'd have to take off the headlight assembly to diagnose the problem. I don't want to have to pay a lot for what may turn out to be a simple fix.
     
    #1 Shawn W., Feb 26, 2023
  2. pasadena_commut

    pasadena_commut Senior Member

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    HIDs or halogens? As I understand it the former have a ballast for each headlight, so cycling the power could reset that component if it is marginal. I don't know if there are separate relays for each headlight for halogens. There is a wiring diagram in this thread:

    headlight system | PriusChat

    but it isn't very high resolution and there are a lot of words I cannot read. There are two relays in the upper right of the diagram. If those are L vs. R relays that might be it. One looks like "MILF Relay", which cannot possibly be right, and the other is maybe "DIM relay". So probably not L vs. R, but since I'm just guessing what those labels are, I cannot rule it out.

    I would also suggest you swap the positions of the bulbs and see if the fault moves with the bulb. If it does, just replace that bulb.
     
    #2 pasadena_commut, Feb 26, 2023
  3. Shawn W.

    Shawn W. Junior Member

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    Thanks for the thread. The bulbs are just standard halogen. I'll mention what's in that thread to my mechanic and see what he makes of it.
     
    #3 Shawn W., Feb 27, 2023
  4. TMR-JWAP

    TMR-JWAP Senior Member

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    Does your car have fog lights?
     
    #4 TMR-JWAP, Feb 28, 2023
  5. Shawn W.

    Shawn W. Junior Member

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    Yes, it does.
     
    #5 Shawn W., Feb 28, 2023
  6. TMR-JWAP

    TMR-JWAP Senior Member

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    #6 TMR-JWAP, Feb 28, 2023
  7. Shawn W.

    Shawn W. Junior Member

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    #7 Shawn W., Feb 28, 2023
  8. mr_guy_mann

    mr_guy_mann Senior Member

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    The ballast transformer that powers the bulb could be failing, but a bad HID bulb is more likely. The easiest test is to "substitute a known good bulb" and see.

    Posted via the PriusChat mobile app.
     
    #8 mr_guy_mann, Feb 28, 2023
  9. ColoradoCrow

    ColoradoCrow Active Member

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    Yup. This exactly. Swap the bulbs and that will tell you. I had the same issue. I bought 2 New HID bulbs and all still working 2 years later. No issues. Just now need new housings due to age of the plastics cooking in the sun.
     
    #9 ColoradoCrow, Mar 1, 2023
  10. Shawn W.

    Shawn W. Junior Member

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    Hey, @TMR-JWAP, I've tried to order from this company, but I keep getting an error message on PayPal, no matter which browser I use, and I've tried contacting the company about it, but they're not responding, so are you sure that they're still in business?
     
    #10 Shawn W., Mar 8, 2023
  11. Gino Veltri

    Gino Veltri Member

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    it is the bulbs. I was confused because mine wouldnt come on unless i smacked the headlight . Then the passenger side one started doing it to. Would reliably turn on each and every time but the light tap required turned into a hard smack over time. Weirdest way for a bulb to burn out ive ever heard of. Replaced bulbs, no more problemo
     
    #11 Gino Veltri, Mar 11, 2023
  12. Shawn W.

    Shawn W. Junior Member

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    Gino, where'd you get your replacements? I tried to order from Onyx as was suggested, but I can't.
     
    #12 Shawn W., Mar 12, 2023
  13. Frontporch

    Frontporch Member

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    I believe I ordered from rock auto. There were warnings about counterfeit bulbs on amazon and eBay and these bulbs aren’t cheap

    I was also surprised that the hid could go dark and then come back on and work a good while longer. It’s nice you get a warning like that.
     
    #13 Frontporch, Mar 12, 2023
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