2007 Headlight dead even after OEM replacement

Discussion in 'Gen 2 Prius Technical Discussion' started by xplode196, May 12, 2017.

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  1. xplode196

    xplode196 New Member

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    Hello,

    A couple months ago my passenger bulb starting going on off intermittently. Turning the lights on and off or the car on/off seemed to fix it until it died. Had some maintenance done at the dealer and asked them to also throw in a genuine Toyota HID bulb.

    The bulb will still not turn on. The dealer is asking to replace the ECU, but they are unsure of what the problem really is. My question is, what should I do? They said the headlight assembly was getting power, and a rudimentary check showed the ballast was okay. Not sure how to proceed.

    Thanks for your help.
     
  2. davecook89t

    davecook89t Member

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    Does it turn on and then die or not come on at all? The car is not throwing any codes, correct? I would think if the ECU needed replacement, there should be some kind of code registered. Is it possible to switch the bulbs on the front to confirm that the bulb on the passenger side has not died prematurely? What voltage are you getting from the ballast to prove that it is not at fault?
     
  3. xplode196

    xplode196 New Member

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    I only know what the dealer told me. They threw in a Toyota bulb, it apparently was on for a short time but refused to come back on.

    I do not see any codes in the car dash, nor did the dealership say there were any. I took the car to a mechanic earlier this month who swapped the bulbs and said the original bulb I had (3rd party Sylvania) was fine in the drivers headlight then.

    The dealership pointed out that the Sylvania bulb was truly dead now.

    I don't have any numbers for ballast voltage.
     
  4. davecook89t

    davecook89t Member

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    I'd be a little suspicious of anything that dealership told you, especially if they said it was a Toyota bulb (to the best of my knowledge, they were all manufactured by someone other than Toyota), and if they are suggesting you replace the ECU without telling you how that could cause your problem. I believe others have had varying experiences with the longevity of replacement bulbs. It should not be a big job to pull the bulb out of the passenger side to see what you've got. I've had good luck with the Philips bulbs I ordered from Amazon so far (
    ), but it's only been about 3 months since I put them in.

    I would suspect the bulb more than the ballast if it will not turn on at all.
     
  5. xplode196

    xplode196 New Member

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    So I shouk
    So you think I should try putting a spare Sylvania or Phillips bulb in there myself first? I will do that soon then. Otherwise what else should I do, in the event that bulb doesn't work?
     
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  6. davecook89t

    davecook89t Member

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    You will need to get a multi-meter (about $20), if you don't already have one and get access to a repair manual (obsidiancorp.com has some links, I expect there will be a nominal fee to use most of them, I have used alldatadiy.com and found it to be useful) to check whether the ballast voltage is within range or look for possible wiring problems. I could tell you to check the continuity of various connections, but I believe you may be exposing yourself to high voltage if you are not sure what you are doing, so it's better to follow the instructions in the repair manual to diagnose the issue. Also, be careful not to touch the glass part of the bulbs when you are handling them. The oil that may be on your fingers will shorten the life of the bulb (hard to believe, I know). Good luck, and let us know what you find.
     
  7. Longinus876

    Longinus876 New Member

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    I just had the dealer tell me that they needed to remove the front bumper ('05
     
  8. Prodigyplace

    Prodigyplace Senior Member

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  9. JC91006

    JC91006 Senior Member

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    if the mechanic has fat hands, he would need to remove the bumper. But that would only slow down his work a few minutes
     
  10. davecook89t

    davecook89t Member

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    That may be what the "book" says. For the passenger side, removing the bumper (cover) is definitely not necessary. For the driver side, I was able to pull the headlight assembly out after removing the bumper cover attachments on that side and bending it (the cover) slightly. (The cover is flexible plastic, it won't lose its shape or break with the small amount of bending that is necessary.) If you are lucky, the plastic ring holding the headlight assembly together can be rotated slightly counter-clockwise by reaching through the gap behind the headlight on the driver side. In that case, it really is a 5 minute job without removing anything, as the woman from Luscious Garage demonstrates on YouTube.
     
  11. JC91006

    JC91006 Senior Member

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    The bumper cover slides right off. 4 bolts in the front, 1 bolts on each fender. Easy 5 minute job....or less.

    that's how I replace my headlights. I slide the bumper cover off....it's so easy
     
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  12. davecook89t

    davecook89t Member

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    >The bumper cover slides right off. 4 bolts in the front, 1 bolts on each fender. Easy 5 minute job....or less.

    that's how I replace my headlights. I slide the bumper cover off....it's so easy

    Unfortunately, I was having trouble removing some of the bolts on the front of my cover, which is why I opted to not remove all of them. Even with that, it took me much longer than 5 minutes. In the end, I was just happy I was able to get the job done in my own unconventional way.
     
  13. ericbecky

    ericbecky Hybrid Battery Hero

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    Partially removing the bumper cover sense for most folks.
    All parts are easily accessible and easily viewable. Nearly eliminates common errors like improperly reattach ingredients the wire holder, or inadvertently touching the glass part of the bulb.

    If doing diagnostic work yourself you could swap a know good bulb into the cfailing" fixture. Or swap the possible bad bulb into a known good fixture.

    Could also swap the known good ballast with the possibly bad ballast.

    If you have to pay for the labor each time this may not be cost effective.

    I'd be curious to hear how they ruled out the ballast.

    And are they saying the ballast is a different component than the ECU? Just want to be sure if terms being used here.
     
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  14. 69shovlhed

    69shovlhed Surly tree hugger

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    what brand of bulb is best for hid? mine is starting to flicker and I want to replace it before it fails completely.

    bumper does come off pretty easy, especially if you have a helper.
     
  15. ericbecky

    ericbecky Hybrid Battery Hero

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    Just to be clear, what folks call the HID ballast, the dealer often calls the "headlight light control ECU sub- assembly".

    So perhaps they feel the bulb is good and the ballast is actually the issue.

    I would say that is likely since you have had the issue for some time and the turn light off/on tricked worked for a while.

    A failing ballast can unfortunately also damage a good bulb. So replacing the bulb but not replacing the ballast leads to damaging the good bulb. Problem won't be resolved until you replace the ballast. And possibly the newly damaged, previously good, bulb.
     
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  16. davecook89t

    davecook89t Member

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    > And are they saying the ballast is a different component than the ECU? Just want to be sure if terms being used here.

    I never considered the possibility that by the term "ECU" the dealer meant "ballast". That would make more sense. Maybe the dealer's advice was less nonsensical than it seemed to me.
     
    #16 davecook89t, Dec 7, 2017
    Last edited: Dec 7, 2017
  17. davecook89t

    davecook89t Member

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    It's been 9 months now and we are having no issue at all with the 2 Philips bulbs I bought from Amazon (link in my post above), and we leave the headlight switch permanently in the "on" position. (I wish the 2007 had DRLs that we could use instead.)
     
  18. ericbecky

    ericbecky Hybrid Battery Hero

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    Interesting. Others always make sure to turn off their lights before shutting down the car.
    The theory was that it would prevent a surge of power on startup.
     
  19. davecook89t

    davecook89t Member

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    > Interesting. Others always make sure to turn off their lights before shutting down the car.
    The theory was that it would prevent a surge of power on startup.

    If that's a known fact, I guess we may have to change our normal practice. Since the wife mainly drives that car now, and she is still not familiar with all the controls, I thought it would be easier just to leave the lights on all the time. On the other hand, I may still continue to do what we've been doing, given that I didn't expect the car to last this long anyway. (With 253k miles, it will be given to charity as soon as we have a major problem with it.)

    Would the same thing apply to the DRLs on the 2017 Prius? I may need to start turning the switch off for them. I don't want to have to mess with anything on that car for a good long time.
     
  20. Prodigyplace

    Prodigyplace Senior Member

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    On the 2017 the lights are LED and draw much less current. They would not cause a surge.
     
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