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Location of headlight relay on a 2011 Prius?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Oxowowmom, Apr 28, 2015.

  1. Oxowowmom

    Oxowowmom New Member

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    Location:
    Silver Spring, MD
    Vehicle:
    2011 Prius
    Model:
    One
    Can someone tell me where the relay for the headlights on a 2011 Prius is located and how to get to it? My low and high beams both stopped working.

    The fuses in the engine compartment appear to be fine. The stalk switch on the steering column works as well- the high/low beam indicator lights turn on in the instrument display as expected when I turn the stalk switch or pull it.

    However, I don't hear the click of a relay when turning on the low/high beams or flashing the high beams.

    I've pulled off the dash panel under the left side of the steering column (the one with the trunk release handle) to see if I could get a better look in the vicinity of the passenger compartment fuse box, however I see no relays. I can hear the click of the turn signal and interior light relays so I know there are some in the area!

    I've searched Google high and low and have yet to come up with any leads- to say this has been frustrating is an understatement.
     
    #1 Oxowowmom, Apr 28, 2015
  2. xliderider

    xliderider Senior Member

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    Vehicle:
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    Model:
    Three
    If it's by the turn signals flasher relay, then it's a real PITA to reach. Lie on your back in the driver's footwell, put your head by the brake pedal and look up into the dash above. The turn signal relay is blue.
     
    #2 xliderider, Apr 28, 2015
  3. ChapmanF

    ChapmanF Senior Member

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    Vehicle:
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    Check your electrical wiring diagram manual on techinfo.toyota.com - it's worth a hundred guesses on PriusChat (unless you have the luck that your post gets seen by somebody who just worked on the same issue yesterday, which does sometimes happen).

    In case your issue turns out to be something other than the relay, you'll need more of the information that's in that book anyway.

    Cheers,
    -Chap
     
    #3 ChapmanF, Apr 28, 2015
  4. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Location:
    Green Valley, AZ
    Vehicle:
    2015 Prius
    Model:
    Two
    Look in the relay/fuse box next to the inverter. A headlight relay typically is going to be located in the engine compartment, not the passenger compartment, to minimize the wire length running to the lights, which draw a reasonable amount of power. Also check the headlight fuses in that box. "Check" means that you remove the fuses, one at a time, and measure continuity using an ohmmeter.

    The #1 integration relay controls 12V power to the low beam headlights, and the DIM relay controls 12V power to the high beam headlights.

    The Main Body ECU controls power to those two relays. So the troubleshooting for this issue may not be quite as simple as you would like - since the headlight switch on the steering column just provides a request to the Main Body ECU and is not directly wired to the headlight relays...

    Amazingly (to me at least) you need Mini VCI or Toyota Techstream to exercise the various light controls and verify the Main Body ECU has received and properly interpreted the commands provided by the light switches - to activate the headlights high or low beam, taillights, and fog lights.

    So I suppose the troubleshooting would start by verifying the Main Body ECU and the headlight switch are communicating with each other. Assuming the ECU is reporting the commands from the headlight switch correctly, then the next step would be to look at the #1 integration relay to figure out why you don't have headlight low beams.
     
    #4 Patrick Wong, Apr 29, 2015
    Last edited: Apr 29, 2015
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