Airbag SRS ECU Failure causes Hybrid System Malfunction

Discussion in 'Gen 4 Prius Care, Maintenance and Troubleshooting' started by Dan Dolsberry, Jan 28, 2026 at 10:17 AM.

  1. Dan Dolsberry

    Dan Dolsberry New Member

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    I suddenly got many warnings, Hybrid System Malfunction, Pre Collision Malfunction, ...
    The scanner showed a SRS ECU airbag failure. It was cleared but then came back up.
    Took it to the dealer, they replaced the part, car works fine.
    Seems crazy, why would SRS ECU failure cause about 6 unrelated alarms. Toyota rep said she never heard of this. Any explanation?
    2017 Prius Three
     
    #1 Dan Dolsberry, Jan 28, 2026 at 10:17 AM
  2. bisco

    bisco cookie crumbler

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    many of the eco's are tied together. the warnings have no detail, that's why you read the trouble codes.
     
    #2 bisco, Jan 28, 2026 at 9:14 PM
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  3. BiomedO1

    BiomedO1 Senior Member

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    The SRS ECU failed in such a manner that it disrupted communications with those other ECUs. When the master ECU couldn't get a decent reply from them. It flagged all of them as defective.

    YMMV
     
    #3 BiomedO1, Jan 29, 2026 at 1:04 AM
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  4. ChapmanF

    ChapmanF Senior Member

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    I would think not so much 'disrupted communications' and more just the ECUs talking about each other the way they normally do. There isn't any single 'master ECU' that flags others as defective, but various ECUs do routinely communicate with each other and can set trouble codes of their own based on what they hear.

    I don't have a specifically gen 4 manual to look in, but as of gen 3 for sure, the HV control ECU likes to stay aware of what the SRS ECU is saying. Codes like P1606, P3107, or U0151 can be set in the HV control ECU based on what it hears (or doesn't hear) from the SRS ECU.

    Then, in turn, the skid ECU (responsible for the brakes, ABS, and stability control and their associated warning lights) has its own familiar codes C1259 and C1310 that it sets when it is notified of codes in the HV control ECU.

    Won't know for sure if the dealer didn't report what the trouble codes were, but my guess would be those were among them.
     
    #4 ChapmanF, Jan 29, 2026 at 10:40 AM
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