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Front blinkers not working: Bulbs/fuses are fine

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by MPLP, Oct 4, 2021.

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  1. MPLP

    MPLP New Member

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    Location:
    Marysville, WA
    Vehicle:
    2010 Prius
    Model:
    II
    Hey! I could use a bit of help. I'm in a pinch (mid-divorce/custody battle), and I don't have the time/money to leave my only mode of transportation in the shop. I'm trying to fix this myself.

    My 2010 Prius front blinkers stopped working - both for emergency lights and blinkers. The back blinkers and emergency lights work fine. I've checked the fuses and bulbs and they're fine. I even changed one of the bulbs, just to verify.

    Does anyone have any idea about what else to check?

    Thanks!
     
    #1 MPLP, Oct 4, 2021
  2. rjparker

    rjparker Tu Humilde Sirviente

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    It is almost certainly the wiring or connectors around the front bulbs. Or the bulbs. The drawing below indicates the same outputs directly run the back bulbs. So that eliminates the electronics and fuses.

    I would double check the bulb that you replaced was actually the turn indicator. People have confused these hard to access bulbs with other bulbs on the headlight housing.

    I would then verify bulb socket voltage to chassis with a voltmeter. If it is there, then the fault is in the ground wire from the socket to chassis. In fact, the A3 ground connection is the only unique single point of failure for the front bulbs.

    Finally most mechanics and advanced diy'ers could trace this circuit easily. This is not a dealer only job. Overall, with these symptoms, this is pretty basic electrical troubleshooting.
    17E907E7-7D34-4D70-BBE7-38A6C38CE615.jpeg
     
    #2 rjparker, Oct 4, 2021
  3. MPLP

    MPLP New Member

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    Vehicle:
    2010 Prius
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    II
    Thank you for the quick reply! The wiring diagram definitely helped.

    I did my homework when locating the front blinkers -they're really a pain to access. Verifying the voltage was a simple thing to do - sorry for not thinking to do it earlier. There was no voltage (i.e. about 0.1 V) when I ground the plug to a large bolt connected to the chassis underneath. It was hard to see/get under there to look at the bulb socket, so I just connected it to both side of the plug.

    I did the same for both sides of the car - no voltage in either socket.

    Part of the reason I'm nervous about taking it the mechanic, so that I think my ex-wife got screwed over when she bought this car. She bought it without telling me from a mechanic. When I look inside, I see a number of sides of a pretty serious wreck (there's pieces of plastic and attachment points that are broken), but the title is clean. I'm pretty sure it got in a wreck, and the mechanic fixed it up on the downlow.

    Any other suggestions for where to look?
    I have some experience with DIY stuff - Until recently, I used to do my own maintenance and repairs (except for tires) on a 1965 Honda Nighthawk, including some troubleshooting of the electric system. Prius's are much more complicated.
     
    #3 MPLP, Oct 4, 2021
  4. rjparker

    rjparker Tu Humilde Sirviente

    Joined:
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    Location:
    Texas Hill Country
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    Hopefully you were not directly connecting the "plug" to ground. You take the positive of the dc voltmeter to the "plug" terminal and the ground of the meter to chassis. I would verify the meter setup and its probes at the fuse box positive jump point.

    Of course be sure the turn signal or hazard light is on first. Verify the back lights still work. Since they are flashing, expect the dc voltage to jump around.

    If that does not narrow things down, I would find connectors A3 and CA1 and check them.

    7B1A1537-52FC-47F0-B01E-0EC380EB556E.jpeg
    6B25E6E7-D008-43E9-8F81-7A22A453A7C4.jpeg O
     
    #4 rjparker, Oct 5, 2021
    burrito likes this.
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