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How do I fix the dreaded HID headlight problem (2nd gen)?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by sanders, Jun 9, 2015.

  1. sanders

    sanders Junior Member

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    I just bought a used 2005 Prius complete with the dreaded HID headlight problem. Both headlights turn on, but the right headlight intermittently turns off. The previous owner replaced the bulb and the computer ("headlight control module"), to no avail. Can someone please tell me how to fix the intermittent headlight problem? Also, is the ballast the same as the "headlight control module"?
     
    #1 sanders, Jun 9, 2015
  2. Priusyipee

    Priusyipee Active Member

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    Hi! Welcome to Prius Chat!
    You don't mention how long you have owned the car nor when the owner last changed the bulb. They don't last forever. It's an easy DIY fix.
     
    #2 Priusyipee, Jun 9, 2015
  3. sanders

    sanders Junior Member

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    I just got the car last week. The previous owner replaced the bulb and computer trying to fix the problem, but neither of those worked. Should I try replacing the ballast? Thanks!
     
    #3 sanders, Jun 9, 2015
  4. Bill the Engineer

    Bill the Engineer Senior Member

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    I have been having the same problem with my 2004 for about 2 years now. Mine only happens when it is wet out, or when the temperature is well below freezing. I have not changed the bulb, and things have not gotten worse in 2 years. I'm looking forward to the replies here to see what root causes others found.

    Bill the Engineer
     
    #4 Bill the Engineer, Jun 9, 2015
  5. Beachbummm

    Beachbummm Senior Member

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    this is why I buy the base models...no issues with stuff like this..I think Id just abandon the factory set up and go with a standard bulbs and wiring harness from a junk yard..fixed for ever for under 100 bucks
    BUT if you have a few days to read through these posts you might find the answer
    Headlight problem | PriusChat
     
    #5 Beachbummm, Jun 9, 2015
  6. Priusyipee

    Priusyipee Active Member

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    Either swap the bulb from the left side or buy a new bulb. You should isolate the problem first by determining if the problem lies with the bulb itself. Sometimes, the cheap, aftermarket bulbs are duds right out of the package. Also confirm that the correct bulb was installed for that model year.
     
    #6 Priusyipee, Jun 9, 2015
  7. sanders

    sanders Junior Member

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    Thanks everyone. I figured out it was the bulb, after all. I'm thankful for an easy fix. For Bill the Engineer and others, here is some helpful info I came across:

    "It's unclear if the previous owner used crap or counterfeit bulbs vs. genuine quality Philips D2R bulbs (see Not All Bulbs Are Created Equal Not all HID Bulbs are created equal | PriusChat). Yes, I believe ballast and that control module are one and the same.
    If they had a mismatch (e.g. used D4R on a ballast meant for D2R, there WILL Be problems). 04-05 Prius used a different bulb and ballast than 06-09. Latter went to D4R which are mercury free."

    One more helpful link:
    Headlight Water Condensation Leads to HID Ballast Failure Headlight Water & Condensation leads to HID Ballast Failure | PriusChat

    Good luck!
     
    #7 sanders, Jun 10, 2015
  8. Priusyipee

    Priusyipee Active Member

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    Very pleased that you were able to determine that the bulb was the problem. All too often I read posts from those who try to cut corners by buying cheaper aftermarket products that do not meet quality standards. You get what you pay for. :eek:
     
    #8 Priusyipee, Jun 10, 2015
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