No power to passenger headlight

Discussion in 'Gen 4 Prius Care, Maintenance and Troubleshooting' started by Chris Rose, Mar 13, 2020.

  1. Chris Rose

    Chris Rose New Member

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    Mar 13, 2020
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    Location:
    Waldo FL
    Vehicle:
    2016 Prius
    Model:
    Two Eco
    Hello, I bought a 2016 Toyota Prius that is out of warranty, the passenger headlight is not working, neither on low or high beam. The marker lights work and the turn signal are working. I've checked all fuses and every exterior light is working except the the main passenger lamp. The "HEADLIGHT SYSTEM MALFUNCTION" is stated on the dash. I am not getting power on the blue positive wire which is seen in the pictures. With the headlights on, the driver side harness plug it has power to three terminals and the passenger side only two, lacking power to the blue wire, there is good ground. Does anyone have a schematic that shows where this wire leads, possibly what fuse or relay it runs into, thanks.


    IMG_20200313_184244_043.jpg IMG_20200313_184432_608.jpg IMG_20200313_184552_010.jpg MVIMG_20200313_183437.jpg
     
  2. Elektroingenieur

    Elektroingenieur Senior Member

    Joined:
    Jan 8, 2017
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    Location:
    California
    Vehicle:
    2016 Prius
    Model:
    Three Touring
    Find this in the Electrical Wiring Diagram (more info). Check the H-LP RH fuse; the No. 1 integration relay, a module that contains the H-LP RH relay itself; and the associated wiring.

    You should find 12 volts from the H-LP RH fuse at terminal 1B-8 (blue wire), which is connected to the fixed contact and coil of the H-LP RH relay. The other side of the coil is 1A-11 (beige wire), which should be at low voltage to ground; and the moving contact is 1A-12 (blue wire, to terminal A34-3 on the connector, seen in your photos, for the headlight assembly), which should also have 12 volts, of course.

    The fuse and relay are both in the No. 1 engine room relay block, under the hood on the driver’s side. See these Repair Manual topics for details:
    • Vehicle Exterior: Lighting System (w/o AFS): B2430,B2431; LED Headlight LH [RH] Circuit Malfunction
    • Power Source/Network: Power Distribution: Integration Relay: Inspection
    If the relay module (part number 82641-47050, shown in catalog Figure 84-01, Switch & Relay & Computer) is defective, and you can’t find a used one, keep in mind that the same part is used on Prius cars built for sale in Japan, so it’s available from exporters.
     
    Chris Rose and frodoz737 like this.
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