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Headlight issue

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by mercurisx, Feb 19, 2014.

  1. mercurisx

    mercurisx New Member

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    Vehicle:
    2007 Prius
    Model:
    II
    I drive a 2007 Prius - about 185k miles on it and purchased it used a few years ago. It's needed minor maintenance to it but overall it's served me well.

    I hopped in my car this evening and went to turn on the headlights. After turning the knob, the lights came on - then both faded and turned off. These are halogen bulbs. Here's what I have tested - I don't have light in my driveway so it will have to wait until my lunch break at work, so I'm hoping to get some feedback to know what I'm looking for.

    -Headlights do NOT turn on after restarting the car, or repeatedly turning the headlight knob
    -High beams DO work
    -Turn signals / Hazards DO work
    -Parking lights (middle selection on knob) do NOT work
    -Rear lights all work normally.
    -When turning on the headlight the knob, the dashboard 'headlight' indicator turns on.

    Does this sound like a fuse? I understand the HB/LB R/L fuses are all isolated, what are the chances two of them would blow at once? Anywhere else I should be looking? Thanks for any help! I don't have a lot of money or time to go to a dealer so I'm hoping to resolve it myself.
     
  2. dorunron

    dorunron Senior Member

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    You can check the fuses and see if they are blown. It would not surprise me if you find in the end that you simply have to install two new bulbs and go on your way.

    I had that happen to me on another car. Turned on headlights, burned for a second or two, then went out. Thought it was the switch or something else. Turned out I just needed new headlights. This was when everyone was using "sealed" beams.

    If your bulbs are original, I am sure they are due for replacement. They don't last forever.

    Hope you get it resolved to fit your budget and time constraints. Good luck to you!
     
  3. ahmeow

    ahmeow Prius Lover

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    As you've said, check the related fuses first. See what you found.
     
  4. mercurisx

    mercurisx New Member

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    II
    Thanks I forgot to mention I've changed (both) headlight bulbs several times since I bought the car. I change them at different times so I always have one for potential night driving if one burns out.
     
  5. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Two
    "-Headlights do NOT turn on after restarting the car, or repeatedly turning the headlight knob
    -High beams DO work
    -Turn signals / Hazards DO work
    -Parking lights (middle selection on knob) do NOT work
    -Rear lights all work normally."
    Regarding the low beam headlights, I suggest that you remove and test the DIM relay which should have five relay terminals. Use an ohmmeter to find the relay coil terminals, resistance probably will be around 100 ohms or so. Then you will know the other three terminals are used for switching between low beams and high beams.

    One of those three terminals will switch back and forth between the other two terminals as the relay coil is energized. You should find continuity between two of those terminals when no power is applied to the relay coil and the resistance should be 0.5 ohms or less. When 12VDC is applied to the coil, then continuity will switch to the other of the three terminals and again, the resistance should be 0.5 ohms or less.

    If the DIM relay tests OK, then perhaps both low beam bulbs burnt out simultaneously but I think that is a low probability occurrence. You can also check the fuses for the low beams. If you can pull out the fuse, you can use your ohmmeter to check resistance across the low beam filament to ground. If you don't measure a relatively low resistance from one of the fuse terminals to ground, then you'll know the low beam filament burnt out.

    Regarding your statement that "Parking lights (middle selection on knob) do NOT work", combined with "Rear lights all work normally", I interpret this to mean that the front side marker lights are the only lights that do not operate in the parking light position. The only rear lights that I expect to be on, when the parking light switch is on, would be the tail lights and the license plate bulbs.

    If this is correct, then I suggest you check the two front side marker light bulbs and replace if needed.