Ready light not showing up, hybrid battery and battery replaced

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Nick123293, Jan 13, 2026 at 8:09 PM.

  1. Nick123293

    Nick123293 New Member

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    Hello,
    I have a 2004 Prius which has been sitting on my driveway for around a year and a half. I have recently been trying to get it working and since then have found that the hybrid battery is dead. I purchased a charger for the hybrid battery, charged the working cells and replaced the broken ones and then reinstalled the hybrid battery, originally upon doing this my the car would start and run however the engine would not turn on (I only test ran it for around 5 minutes after replacing the battery). That was around 2 weeks ago and now upon trying to start it all of the warning lights come on (except maintenance required) and the ready light will not come on, the car turns on (not the engine) but the car can only move from park to manual (not drive or reverse). I have since replaced the 12V battery to no avail, the same problems occur. I am trying to diagnose the issue but I am at a loss. My emergency brake light is stuck as on however my brake lights do come on when I push the brake. Additionally, when I check the voltage on my newly purchased battery it reads 12.4 from the back, but when I check the voltage from the hood of the car it reads around 11V, and the car for some reason will not turn off if I hold the brake when I press the power button, I can only turn it off when I am not holding the brake. Turning on the car works as normal except for not being able to put it in drive and all of the dash lights except the ready. Attached is a picture of what my dashboard looks like when I turn it on. Does anyone know what potential issues may be?
     

    Attached Files:

  2. Trombone

    Trombone Active Member

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    Post in the Gen. 2 forum, this is Gen. 1.
     
  3. Brian1954

    Brian1954 Senior Member

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    Use a Prius capable scanner to read the trouble codes.
     
  4. Tombukt2

    Tombukt2 Senior Member

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    You locked out at pedal push and button press to get ready . how many clicks do you hear in relays at rear listen carefully clik on click off click on . I bet you're missing the last set of clicks so you're clicked off and holding . Because car sees trouble . Codes ?????
     
  5. VintagePrius

    VintagePrius Junior Member

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    I would check why 12.4v @ back and 11v @ front. I think if the HV battery is charged the 12v battery should be getting upwards of 13v from the DC to DC converter when ignition is on. Also the ECUs and other electronics are probably getting less than 11v which might make for strange faults like not being able to turn it off—when you hold brake on and the brake lights are on that would drop the 11v even lower, but volts will come back up with brake not depressed allowing it to function a bit more normal.

    Good luck.
     
  6. Tombukt2

    Tombukt2 Senior Member

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    That's correct it only turns off when you're not touching the brake. You're having to hold the button to get the car off. It used to be press and release and off it went.
     
  7. Brian1954

    Brian1954 Senior Member

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    I agree with you. The OP should check why there is only 11v at the front.

    The DC to DC converter does not charge the 12v battery when the ignition is on. The DC to DC only charges the 12v battery when the car is in READY. The OP's car does not go into READY.