Driver side Low Beam stopped working

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by zebelkhan, Jan 24, 2021.

  1. zebelkhan

    zebelkhan Member in good standing

    Joined:
    Mar 14, 2012
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    Location:
    Morgan Hill, CA
    Vehicle:
    2012 Prius
    Model:
    Two
    Left low beam on my 2012 base Prius (with Halogen bulb) went out a few days ago. Right side was working so I thought it could be the bulb. So I bought a new one but that was not it. Then I looked for the fuse. I know, I should have done that first but I cannot find any low beam headlight fuses in the fuse box in the engine compartment or the fuse box inside the car.

    While searching on the internet I discovered that apparently there are no low beam headlight fuses for my Prius (shame on you Toyota) but there is a 40 amp fuse (part of 3 fuses attached to each other) that feeds power to an integration relay that in turn powers the low beam headlights. Not sure where the integration relay is but since my right side low beam is still working, I do not think that is the problem. I checked the 40 amp fuse anyways using a multimeter and it is good but cannot test the relay since I don't know where it is. Light socket and wires seem to be in good shape too. I just don't have any power going to the bulb socket.

    I would appreciate any guidance from all the talented people on this board. I am sure someone must have run into a similar problem with one headlight having gone out for something other than the bulb. Help!

    Edit: I found the Integration Relay but it seems like I have to pull the whole fuse box to access the wires below it. This is crazy! It seems that fuses and relays for headlights should be the most accessible as they are safety related. Hopefully someone will be able to help with the solution. I really don't want to mess with the fuse box!
     
    #1 zebelkhan, Jan 24, 2021
    Last edited: Jan 24, 2021
  2. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
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    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    When stuff like that happens to me I just get out a meter and the wiring diagram (more info) and start checking along the circuit until I find where good changed to not-good. Other than the tedium, it's straightforward and leads to the solution.
     
  3. rjparker

    rjparker Senior Member

    Joined:
    Jun 6, 2008
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    Location:
    Texas Hill Country
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    I would say your h11 to h9 conversion may have come back to haunt you. Either your replacement h9 bulb has not been modified to fit or the increased current of the h9 has taken out the integration relay.
     
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