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HID headlight lights up and then flickers out: Is it the Ballast?

Discussion in 'Gen 2 Prius Technical Discussion' started by wlai, Oct 17, 2021.

  1. wlai

    wlai Junior Member

    Joined:
    Sep 22, 2007
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    Location:
    Pacific NW USA
    Vehicle:
    2008 Prius
    Model:
    Touring
    So lately one of my HID headlight will light up, but as I drive it it will flicker out. Turning it off and on relights it but it'll flicker out again.

    Could the HID Ballast cause that behavior? I somehow has the impression that the ballast is only use when the light is first starting up and is subsequently unused once the bulb is already lit.

    Thanks.
     
    #1 wlai, Oct 17, 2021
  2. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

    Joined:
    May 12, 2018
    7,427
    6,913
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    Location:
    Pennsylvania
    Vehicle:
    2018 Prius c
    Model:
    Two
    Sounds more like a level check failure.

    When the headlights start up, the control system is supposed to verify that each lamp's automatic leveling system is functioning correctly. If the leveling system gives a negative response (or no response at all) then the corresponding lamp is extinguished to prevent glare hazards.
     
    #2 Leadfoot J. McCoalroller, Oct 17, 2021
  3. L Gunter

    L Gunter New Member

    Joined:
    Aug 3, 2024
    2
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    Location:
    Washington
    Vehicle:
    2006 Prius
    Model:
    N/A
    I'm also having this same symptom and it seems to be worse when driving at high speeds.

    Just finished a 2 hr drive and near the end the lights were flickering and going out every few minutes.

    A quick "off and on again" gets them up and running, but it's annoying as heck and dangerous.

    Anyone find a solution to their headlight flicker?
    Did you replace with better quality bulbs?
    Discover it was a bad ballast?
    Upgrade to LED?
    Find a bad relay?
    Check wiring?
    Something to do with auto leveling and anti-glare measure?
     
    #3 L Gunter, Aug 3, 2024
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