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Start button malfunction

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by cosmin dumitrescu, Aug 14, 2023.

  1. cosmin dumitrescu

    cosmin dumitrescu New Member

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    2008 prius, I had to bleed the brake system a while ago and rebuilt the hybrid battery. Now when I press the start button, board lights up but engine doesn't start. The red warning triangle and other lights are turned on. The start button starts without depressing the brake pedal. That's wired. The engine doesn't start though and the ready green sign blinks twice and disappear. When I want to turn the car off, it will turn off only without depressing the brake pedal. Is it a grounding issue or else?
     
    #1 cosmin dumitrescu, Aug 14, 2023
  2. mr_guy_mann

    mr_guy_mann Senior Member

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    Hello and welcome to PriusChat!

    A common problem that happens is that the orange safety interlock (fuse holder) is not installed correctly.

    It requires three steps. 1) Push the holder into place. 2)Swing the handle in. 3)Slide the handle DOWN until it clicks.

    Beyond that, most any fault that turns on the "master caution" light (red triangle) has set a code in the hybrid control ecu.

    You may need a capable scantool to be able to check all 15 or 16 systems in a Gen2 Prius for codes and data. Here's a thread that reviews several scantool apps and devices.

    https://priuschat.com/index.php?posts/3290690 Screenshot_20230108-154956.jpeg

    FYI your first 5 posts are moderated.

    Posted via the PriusChat mobile app.
     
    #2 mr_guy_mann, Aug 14, 2023
    theory816 and SFO like this.
  3. cosmin dumitrescu

    cosmin dumitrescu New Member

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    Thank you for your prompt response. The orange safety interlock is not the problem. I installed it correctly. I am baffled by the fact that I can "start" the car (not the engine) by not depressing the brake pedal. Something was installed in reverse of a connection missing.
     
    #3 cosmin dumitrescu, Aug 16, 2023
  4. dolj

    dolj Senior Member

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    You don't say what happens if you press the Start button (from OFF) with your foot ON the brake pedal.

    You haven't posted any trouble codes that go along with your dash lights. It would sure be helpful to do that.

    If your current scan tool does not bring up any trouble code, although we know there are codes because you have dash lights illuminated, you can find out what most of them are without a new scan tool. See this post for more information on how to do that.
     
    #4 dolj, Aug 17, 2023
  5. JohnPrius3005

    JohnPrius3005 Active Member

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    May be a combination meter problem. Typically a CM failure causes these types of issues.
     
    #5 JohnPrius3005, Aug 17, 2023
  6. dolj

    dolj Senior Member

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    If you are not getting the READY light on the dash, then your car is not starting. It is either in ACC or IG-ON (See below).



    Prius power cycle modes:
    Mode
    Action​
    1 ACC
    • With the car in OFF; and the foot OFF the brake; press the start button once.
    2 IG-ON
    • If the car is in OFF; with the foot OFF the brake; press the start button twice.
    • If the car is in ACC mode; with the foot still OFF the brake; press the start button once more.
    3 READY
    • With foot ON the brake; press the START button once; this can be done when the car is in any other mode.
    4 OFF
    • If the car is in READY; press the START button once; it does not matter whether the foot is on or off the brake.
    • If the car is in ACC mode; with the foot OFF the brake; press the start button twice.
    • If the car is in IG-ON mode; with the foot OFF the brake; press the start button once.
     
    #6 dolj, Aug 17, 2023
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  7. bisco

    bisco cookie crumbler

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    Brake switch?
     
    #7 bisco, Aug 17, 2023
  8. Aegean

    Aegean Active Member

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    I would start by scanning the codes first. What codes do you read?
     
    #8 Aegean, Aug 17, 2023
  9. cosmin dumitrescu

    cosmin dumitrescu New Member

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    I owned many Prius gen 2 cars in the past 12 years and I successfully rebuilt 4 batteries so far but I never experienced this situation so far. If I start the car normal with my foot on the brake pedal, the board lights up, i hear the battery click twice and the ready button goes off and the warning red triangle comes on. If I want to turn the car off with my foot on the brake pedal, it will not work at all, nothing will happen and the board will stay lit. I rebuilt this battery and changed 4 cells that were dead. Maybe I reverse the battery pack poles, but I am sure I didn't because all the wiring fits perfect. I do not have a scan tool for Prius. This car sat in my parking lot untouched for 3-4 years. Can anything go bad except the batteries?

    I will check that. Thanks.

    I am not a begginer. I owned several gen 2 priuses in 12 years and I know how to operate them. No offence. Thank you for your help. Something does not make sense in how the car behaves.

    4 years ago I drove this vehicle with no problems. After not starting it for 4 years I had to rebuild the battery. I doubt the combination meter would go bad if no power runs through it.
     
    #9 cosmin dumitrescu, Aug 25, 2023
    Last edited by a moderator: Aug 25, 2023
  10. mr_guy_mann

    mr_guy_mann Senior Member

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    If you have a red "master warning" light, then you almost certainly have fault codes in the hybrid control and/or HV battery ecu. It would REALLY be easier if you had a capable scantool to get codes and data from those systems. Several of the ones in my thread are under $100.

    Guessing sometimes works...until it don't.
    (WAG, something's wrong with your "rebuilt" HV battery pack)

    As far as the CM capacitor, age is part of the failure equation (not just use). But if your CM turns on every time you hit the power button, then forget about that (for now).

    Posted via the PriusChat mobile app.
     
    #10 mr_guy_mann, Aug 25, 2023
    Last edited: Aug 25, 2023
    Brian1954 likes this.
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