new here, gen 1 problems, no ready light, won't start

Discussion in 'Generation 1 Prius Discussion' started by Merkurfan, Oct 3, 2025 at 10:25 PM.

  1. Merkurfan

    Merkurfan New Member

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    cars history. ain't got any of it.
    How I got it. Impound sale. no keys.
    how it's going pulled lockset and imobilizer ECU (that little bugger is hard to get with big hands)
    installed the ingnition lock assemby and ECU. key turns on dash, lights up and flashing red security light stops.
    Found car had sat since 19.. high voltage battery, not so high. Found prolong charger in truck charged overnight. battery no good sever packs very low voltage (probably why it's been sitting) went to my favorite salvage yard and they gave me a remaned pack that sat to long and was dead. No problem the prolong can charge it.. installed the pack and connected the 2 prolong leads the same way (and per their directions) charged battery over night.
    the red triangle is gone. Icon T10 (launch basically) says all systems are happy. No codes present in anything (after clearing a P3006 I think it was)
    still won't ready or start
    12 volt battery sitting at 12.8V stays at that when I turn key to "start" but the info screen goes dark (the odometer screen stays list)

    access the data stream from the ECM one line bugs me Start=Proibitied.

    but there is nothing telling me why. Not sure where to go from here.

    Thanks!
     
    #1 Merkurfan, Oct 3, 2025 at 10:25 PM
  2. VintagePrius

    VintagePrius Junior Member

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    Just a possibility…it might be a brake pedal issue.
    To go into READY I think you have to press the brake pedal while pressing the POWER button on a Gen 1. (Not sure as I have a Gen 0) So, if the brake switch is bad or misadjusted, the car won’t see the pedal input.
    Do the brake lights come on when you press the pedal? If not, the switch may be dodgy.
     
    #2 VintagePrius, Oct 4, 2025 at 7:20 AM
  3. Trombone

    Trombone Active Member

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    Key turn readies the gen. 1; no power button. Brake pedal not required to start.
     
    #3 Trombone, Oct 4, 2025 at 7:28 AM
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  4. Tombukt2

    Tombukt2 Senior Member

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    Xr4ti owner?
     
    #4 Tombukt2, Oct 4, 2025 at 9:07 AM
  5. VintagePrius

    VintagePrius Junior Member

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    Ah, so brake pedal switch is not involved in start sequence. In that case can you hear the relay in the back make a noticeable click when you turn key on…maybe the precharge contactor relay. You should also hear fuel pump in back run and some relays/whirrs in engine bay. I don't think the main contactors in back will engage if the 'ready' light isn't lit though.
     
    #5 VintagePrius, Oct 4, 2025 at 5:12 PM
    Last edited: Oct 4, 2025 at 5:42 PM
  6. Trombone

    Trombone Active Member

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    In my ‘02, the 12v voltage immediately shows 13.8 with car “Ready.” I’d check the 12v condition and connections. Could possibly also be fuse(s).
     
    #6 Trombone, Oct 4, 2025 at 7:06 PM
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  7. ChapmanF

    ChapmanF Senior Member

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    Right, the contactors get a strange amount of ink spilled about them here, as if they weren't just simple devices all under control of the HV ECU.

    When you turn the key to START, the HV ECU goes through its whole normal checklist for is this key the right key, are all the other ECUs present and accounted for, are the battery conditions suitable, is this car ok to go READY, and if all of that checks out, it actuates the contactors (three of them, one being for precharge, that last part all goes so fast you just hear a quick click-clicket) and you're in business.

    The owners' manual doesn't say anything about the brake pedal while turning the key to START, so that shouldn't be an issue. It does mention that the shift selector can't be in N, and it mentions holding the key at START until READY appears (which may take longer in, say, winter conditions).

    Because most of the decisions about going READY are made by the HV ECU (the ECM just follows orders when told to make the engine go), a scan tool that shows you what the HV ECU is seeing will probably help the most.
     
    #7 ChapmanF, Oct 4, 2025 at 7:48 PM
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