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Flashing gear lights and more

Discussion in 'Gen 2 Prius Main Forum' started by Rabbi, Jul 13, 2022.

  1. Rabbi

    Rabbi Junior Member

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    Vehicle:
    2005 Prius
    Model:
    ----USA----
    I'm working on a 07 Prius. Here is what I am experiencing and what I've done...

    What's happening:
    When the 12v is plugged in (on the battery positive side), the gear lights and a full gas gauge flash constantly along with a couple other dash lights that stay on (exclamation point with circles and the air bag light). The key does not need to be anywhere in the car or in the slot for this to happen. I can put the key in the slot and try to start the car but it will not start. The mfd, ac, and radio come on when I press the start button without using the brake but not when I use the brake. The hv battery display on the mfd does not register any bars when the mfd is on. I have tried linking up Techstream but get nothing from the OBD2.

    So far I have...
    Replaced the hv battery
    Replaced the 12v battery
    Replaced the gear mechanism, power button and fob mechanism.
    Replaced the main fuse
    Checked all fuses in the car and under the hood (not with a multmeter) and they are not broken

    Questions:
    Since the dash doesn't go off until I unhook the 12v battery, could this be at the combo meter?
    Could it be the inverter?
    Could it be the harness to the 12v?

    I've been working on these cars for several years and have never been stumped like this before. Any help would be appreciated.
     
    #1 Rabbi, Jul 13, 2022
    PriusCamper likes this.
  2. PriusCamper

    PriusCamper Senior Member

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    Vehicle:
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    Model:
    Two
    This is customer's Prius? You only have one FOB?

    My first impression is that perhaps the FOB you are using isn't for this Prius and that's why it won't work when it's in the slot. And the reason why your Prius starts up with nothing in the slot is because somewhere in the car is a lost FOB that does work with the car and it's allowing the car to power up.

    Of course reading further things do seem to get confusing in the way a bad combination meter does, so maybe this isn't the problem. But sure would be a cool resolution if it was and you found the lost FOB.
     
    #2 PriusCamper, Jul 13, 2022
  3. Rabbi

    Rabbi Junior Member

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    2005 Prius
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    ----USA----
    Thanks for the input. I'll check the rest of the car for sure and update what I find later today
     
    #3 Rabbi, Jul 14, 2022
  4. dolj

    dolj Senior Member

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    Correct, that is what happens when 12 V is reconnected. It will stop flashing and show the correct level after it recalculates the level. This can happen after 2 minutes, 2 hours, or 2 days, but will calibrate eventually.
     
    #4 dolj, Jul 14, 2022
  5. mr_guy_mann

    mr_guy_mann Senior Member

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    Four
    Based on your symptoms, my guess is that something is disrupting communications on one or more of the data networks. First step would be to check all fuses in both fuse blocks. You want to see that all fuses are intact and that everything that should have battery B+ power does in fact. Then power up to "ignition on" and see what fuses have "ignition" power that should.

    You'll also need the service manual- both for wiring diagrams and for the sections specifically on multiplex communication and CAN bus.

    You could have a comm wire shorted to ground or power, a bad ecu, or a ecu that's missing a power or ground.

    Posted via the PriusChat mobile app.
     
    #5 mr_guy_mann, Jul 14, 2022
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