P3110 and U0293 Simultaneously

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by ShadeTreeMech, Jul 12, 2025 at 1:44 AM.

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  1. ShadeTreeMech

    ShadeTreeMech Junior Member

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    Hi guys,

    I have a cluster of symptoms with my 2004 and haven’t been able to find the right thread to help diagnose. I’m hoping for some guidance from anyone who may have encountered similar issues or can point me to a thread.

    Scanned codes are 3110 and U0293
    Symptoms:
    · For several months, the clock keeps resetting
    · Gas gauge has suddenly flashed E when full three times over past 3 weeks – resolved on restart.
    · 2 days ago, neither FOB would work in morning – worked a few hours later.
    · My wife drove 40 miles home from work without issue until she pulled into the driveway. She said it wouldn’t shut off for nearly five minutes and flashed the death triangle and “car symbol with exclamation point”. This was the hottest day of the year for us at 100+. The only thing I have checked thus far is inverter pump function (could see turbulence in reservoir).

    I can get through moderate level repairs (Brake actuator replacement, refurbishment of the hybrid battery, combination meter repair, etc.) if I have a good video. I’m not great with these more complex electrical system diagnostics, though. It seems likely the two codes point to where to start, but I would love some guidance from a pro or someone who has encountered the same symptoms. Many thanks in advance.
     
    #1 ShadeTreeMech, Jul 12, 2025 at 1:44 AM
  2. dolj

    dolj Senior Member

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    Sounds like a might be a combination meter or 12 V continuity problem.

    The first thing I would be checking is that the 12 V battery terminals were clean and tight. Then I'd check the 12 V battery was charged and could hold a charge.
     
    #2 dolj, Jul 12, 2025 at 2:59 AM
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  3. ShadeTreeMech

    ShadeTreeMech Junior Member

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    Thank you for the heads-up on 12v - I hadn't even considered that. The 12v is fairly new, but I'll test in AM and check the leads. I would love for that to be the issue. I'll let you know and thank you again.
     
    #3 ShadeTreeMech, Jul 12, 2025 at 3:27 AM
  4. Tombukt2

    Tombukt2 Senior Member

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    Battery is probably going to be your issue or its connections to the little white wire n fuse need be good and in place most issues Prius start at 12 V
     
    #4 Tombukt2, Jul 12, 2025 at 8:45 AM
  5. ShadeTreeMech

    ShadeTreeMech Junior Member

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    I checked the battery connection and voltage and all are fine. Also, I turned it around in driveway to position better and all the warning lights are gone. I haven't scanned codes again, but I'm wondering if this has something to do with the heat. It was very hot and after a long drive idling in driveway when problem emerged. I'm assuming the problem with likely return in similar condition, but I don't want to get stranded proving the theory. Any ideas? Thanks again.
     
    #5 ShadeTreeMech, Jul 12, 2025 at 10:28 PM
  6. Tombukt2

    Tombukt2 Senior Member

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    Voltage standing is ? Car ready is ?
     
    #6 Tombukt2, Jul 13, 2025 at 12:58 AM
  7. ShadeTreeMech

    ShadeTreeMech Junior Member

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    Car off voltage is 12.44 and in "ready" is 12.30. I don't know nominal for "ready" mode, but that seems about right.
     
    #7 ShadeTreeMech, Jul 13, 2025 at 7:35 PM
  8. dolj

    dolj Senior Member

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    READY should be 13.2 V to 14.4 V. 12.3 V in READY indicates the DC/DC converter is not charging the 12 V battery.

    BTW, the DTC U0293 means a communications problem between 2 ECUs. It would be helpful to know which ECUs were experiencing comms problems. The gateway ECU is involved with this DTC, so I would check that the CM is functioning properly, i. e. whether you experience the dash going dark or not.
     
    #8 dolj, Jul 14, 2025 at 12:26 AM
  9. Hayslayer

    Hayslayer Member

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    The majority of those symptoms sure do match up to a poor 12v battery connection. Could be other things, but that would be my first focus since it's easy and cheap.

    Loss of 12v power causes radio reset of saved stations, clock reset, fuel meter reset to one blinking dot (until it recalibrates), loss of the auto up/down function of the driver window, reset of ecu volatile memory like check engine lights, DTCs, fuel trims, etc.

    As for the problem shutting off the car, the Power Source ecu does some weird things when the 12v battery is intermittent. Not only check the actual battery connections, but check the (-) cable where it fastens to the car body. Also make sure the two wires that plug into the (+) terminal fusible link block are actually inserted completely. One heavy gauge and one small gauge. I've seen several times where the small gauge wire is accidently ripped out of its quick connect when the battery gets swapped. That wire is the feedback loop that helps control charging. Considering your "off" and "ready" voltages are a bit whacked, it may be worth looking into.
     
    #9 Hayslayer, Jul 14, 2025 at 1:31 AM
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