2010 Prius won’t go to READY after radio install – Check Hybrid System + dash lights on

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Lavery, May 26, 2026 at 9:35 AM.

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  1. Lavery

    Lavery New Member

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    Vehicle:
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    Model:
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    Hi everyone,

    I have a 2010 Prius and I’m having a starting issue after attempting a radio installation.

    What happened:

    I tried installing an aftermarket radio, then later reinstalled the factory radio. During/after the install, I may have accidentally caused an electrical issue or blown a fuse.


    ⚠️ Current symptoms:

    • Dashboard powers on normally
    • Multiple warning lights appear
    • “Check Hybrid System” message shows
    • Car will NOT go into READY mode
    • Engine does not start
    • Accessories and dash still receive power

    What I’ve checked so far:

    • Reinstalled original factory radio
    • Visually checked a few interior fuses
    • Considering checking AM1 / AM2 / ACC fuses next
    • Haven’t confirmed 12V battery voltage yet

    ❓ Questions:

    1. Does this sound more like a blown AM2/AM1/ACC fuse or a 12V battery issue?
    2. Can a short from a radio install trigger a hybrid system fault like this?
    3. If AM2 is blown, would the car still power on like this but refuse READY?
    4. Should I reset anything after replacing fuses, or will it clear automatically?
    Any guidance would really help — I’m trying to avoid unnecessary part replacement or towing if it’s just a fuse issue.
     

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    #1 Lavery, May 26, 2026 at 9:35 AM
  2. Brian1954

    Brian1954 Senior Member

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    Did you remove the orange safety interlock plug from the hybrid battery?

    You need to use a good scanner to read the trouble codes.
     
    #2 Brian1954, May 26, 2026 at 6:02 PM
  3. ChapmanF

    ChapmanF Senior Member

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    Can you get the E7022 headunit to power up out of the car, on a workbench? I think you need to ground pin 20 of the L40 connector while supplying +12 V at pins 1 and 11. In the dash harness, you should be able to ID pin 20 (GND) as a brown wire, pin 1 (B) as a sky-blue wire, and pin 11 (ACC) as a gray wire.

    In the car, pin 1 (B) is normally supplied 12V at all times, to power the unit in sleep mode, and pin 11 (ACC) will be supplied when the car is in ACC, IG ON, or READY, and those are the times the unit will wake up and look like it's on. On the bench you can just connect those pins together to your 12-volt supply and the thing should boot up.
     
    #3 ChapmanF, May 26, 2026 at 9:38 PM
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