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low beam no power

Discussion in 'Gen 2 Prius Main Forum' started by rickcoup, Oct 7, 2012.

  1. rickcoup

    rickcoup Junior Member

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    I have a 2005 prius. The low beam bulb on the passenger side had a flash the other day and wouldn't be turned on any more. I changed bulb, fuse. It still doesn't work. The high beam on this side and the low and high beam on the other side are fine. I noticed the socket to this bulb is kind of fried. I check the voltage. It shows zero. The dealer told me, they will change the whole circuit harness to fix it and costs $4000 at least.


    Any suggestions?
     
    #1 rickcoup, Oct 7, 2012
  2. Britprius

    Britprius Senior Member

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    The whole harness does not need to be replaced. If the bulb connector needs to be replaced the easy and cheap effective way is to use one from a breakers yard. It does not even need to be from a Prius as most cars use the same H4 connector. The wires can be spliced together to form an effective repair.
     
    #2 Britprius, Oct 7, 2012
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  3. nh7o

    nh7o Off grid since 1980

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    When the dealer says "replace wiring harness" that is a code word for "we don't want your business" or "we don't know how to troubleshoot electrical problems". If you fill in your location, maybe there is an independent shop that can help you.

    +1 suspect that indeed the plug is a likely suspect.
     
    #3 nh7o, Oct 7, 2012
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  4. rickcoup

    rickcoup Junior Member

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    I found the bulb socket at autozone store. So I cut off the old one. But there is no voltage on the wires. So it doesn't look like a problem of the socket either.
     
    #4 rickcoup, Oct 7, 2012
  5. Britprius

    Britprius Senior Member

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    Have you checked the fuses there are two for low beam one for each lamp. Both fuses are supplied by the same relay so if the other dip/low beam works the only thing in the circuit is the fuse. I am trying to upload the circuit but am having problems but I will continue to try.
     
    #5 Britprius, Oct 7, 2012
  6. Britprius

    Britprius Senior Member

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    Still cannot upload the circuit but if you go to the file library the Prius wiring diagram is there go to the last page of (headlamps & fogs WO DRL next to horn jpg) you will see the wiring from the relay split to 2 fuses marked LO LH & LO RH follow the wires to the bulbs on the left of the circuit marked right headlight WO HID (without HID)
     
    #6 Britprius, Oct 7, 2012
  7. rickcoup

    rickcoup Junior Member

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    I swapped the two fuses of left and right low beams, it didn't work. I found the fuse diagram in the manual. The fuse box is located in the top right corner when I open the hood.
     
    #7 rickcoup, Oct 7, 2012
  8. Britprius

    Britprius Senior Member

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    Check the supply to the fuse to see if the fuse is being fed also check with the ohms scale of your meter from the fuse to the end of the wire at the bulb. This will tell you if the wire is open circuit or the connection from the relay to the fuse is open.

    The fuses have two small holes in the top surface that you can probe with the meter.
     
    #8 Britprius, Oct 7, 2012
  9. rickcoup

    rickcoup Junior Member

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    I couldn't upload a picture either. But when I put tips of multimeter into the little holes of fuse. I don't get any voltage, even with those good fuses. I tried when car started or not started.
     
    #9 rickcoup, Oct 7, 2012
  10. Britprius

    Britprius Senior Member

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    I assume your putting one probe on the fuse and the other on a good ground point (clean bolt on engine or bodywork).
     
    #10 Britprius, Oct 7, 2012
  11. rickcoup

    rickcoup Junior Member

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    Yes. I did.

    I took off both fuses. The good side low beam is off as well. So the fuses are located correctly. Then I connect the red tip of multimeter to the fuse socket, and black tip to one bolt of the engine cover, it shows 0.16v. It's the same 0.16v on another fuse socket. I couldn't find any metal place to give a higher voltage.

    The other side of fuse socket give me 0 V.
     
    #11 rickcoup, Oct 7, 2012
  12. Britprius

    Britprius Senior Member

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    When you check fore voltage at the fuse the car should be in ready with the lights on. If the lights are on there must be voltage (around 12v) at the fuse for each light. Check the meter on the jump point terminal in the fuse box (has a red cover over it) this will have 12 volts plus on it.
     
    #12 Britprius, Oct 8, 2012
  13. rickcoup

    rickcoup Junior Member

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    #13 rickcoup, Oct 8, 2012
  14. Britprius

    Britprius Senior Member

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    Check the connections to the lamp on the other side and wire them in the same order so that the original colors end up being connected to the same terminals
     
    #14 Britprius, Oct 8, 2012
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