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2002 Prius keeps dying with 3191 code after 12V battery charge

Discussion in 'Gen II Prius Care, Maintenance and Troubleshooting' started by cantrellme, Dec 28, 2011.

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  1. cantrellme

    cantrellme New Member

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    Your Vehicle Year:
    2002 Prius
    Model:
    I
    My 2002 Toyota Prius keeps dying (triangle of death and OBD Code 3191) after running smoothly for a few seconds each time I start the engine. Clearing the DTC code allows restart. But the check engine light and triangle of death keep returning after a few seconds.

    It has been doing all this since I recharged the 12V battery (which had been drained completely by a dome light left on for 3 days). Initial attempts to recharge the 12V battery were causing current spikes at charger, and (relay?) clicking sound under the hood. So I disconnected positive battery cable and charged the battery in isolation, then reconnected it to the vehicle after charging was complete.

    When I reconnected the recharged 12V battery the vehicle (honking horn) alarm went off. But that stopped when I unlocked door with key. It may not be related, but I'm also hearing a fan-like sound (under driver seat) when ignition key is in run position. I don't recall hearing that sound in the past.

    Any ideas? Do I need to reset the ECU somehow?

    Thanks, Mark
  2. seilerts

    seilerts Battery Curmudgeon

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    One possibility is that the idle learn has been lost. Try taking off the intake and propping open the throttle plate slightly, and see if the car will start.
    1 person likes this.
  3. andyprius

    andyprius Senior Member

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    If you left the dome light on for three days, your 12V Battery may be shot. How are you determining that the charger was effective? Voltages? with load, in aux position and last but not so important is voltage reading in ready ? Are you using self diagnostic battery check or a multimeter?
  4. cantrellme

    cantrellme New Member

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    I can try that. But the car already starts starts easily and sounds like it is running smoothly for 5 or 10 seconds. But then the check engine light comes on and it shuts down with red triangle.

    Thanks,
    Mark
  5. seilerts

    seilerts Battery Curmudgeon

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    It is almost impossible to distinguish a running Prius from a misfiring one by ear.
  6. cantrellme

    cantrellme New Member

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    I agree that the battery may be shot. But voltage reads 13 VDC with engine off. And it cranks and starts the engine easily. I'd check voltage with the engine running, but it doesn't stay running long enough for me to get back there and read the multimeter.

    My low-budget OBD-II reader only displays the 3191 code. Is it possible that some more helpful codes are being stored but are inaccessible to me? Can or should I reset the ECU to factor defaults somehow?

    Thanks,
    Mark
  7. cantrellme

    cantrellme New Member

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    OK. I propped throttle butterfly valve open slightly. Same result. The engine ran for 5 seconds or so and then shut down. While looking around in the throttle body I did notice signs of oil fouling. If that is the issue, what is the mechanism for the ECU detecting the fouling? Do I need to clean a sensor somewhere? It doesn't look like it would be easy to get down in there and clean up that oil fouling I see way down in the intake manifold area.

    Thanks again,
    Mark
  8. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Hi Mark,

    1. Clean the throttle body interior and throttle plate. First, remove the air cleaner housing for access to the throttle body. Then, apply throttle body cleaner to a clean cloth, and use that to wipe off the throttle body interior. Rotate the spring-loaded throttle plate shaft for access to the throttle plate. Do not drown the intake manifold in throttle body cleaner.

    2. Clean the mass air flow sensor. Remove it from the air cleaner housing. Use MAF sensor cleaner to clean the sensor. Do not use throttle body cleaner or any other solvent.

    3. You can snake a cloth or paper towel down into the intake manifold to absorb some of the oil build up you see down there, if you want.

    4. Clear the DTC and see if it returns. If it does, continue with items 5 and 6, and then 8 if all else fails.

    5. When was the last time that the iridium spark plugs were changed? The service interval is 60K miles on Classic. If this is past-due, then replace the plugs with the correct NGK or Denso plugs.

    6. Remove and test the circuit-opening relay. This is located in the relay box near the inverter. This relay provides power to the fuel pump located within the fuel tank. The testing consists of energizing the relay coil, and measuring resistance across the switched contacts using an accurate digital multimeter. If the reading is more than 0.5 ohm, replace the relay.

    7. I doubt that the engine actually is running for the 5 second period. More likely, MG1 is spinning the engine but the engine is not producing power. Do you smell a strong fuel vapor odor at the intake manifold, which will show that fuel is being injected?

    8. If all else fails, you can upgrade the engine ECU with the most recent part number, do a search for TSB EG011-03. 89661-47054 is the latest part number. The engine ECU is located behind the glove compartment and you can look at the currently installed unit to see if it has a downlevel number. The number will be 89661-470xx. If you see some other numbering then you are not looking at the right unit.

    Good luck.
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  9. cantrellme

    cantrellme New Member

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    Patrick:

    I'll give those tips a try.

    Thanks much,
    Mark
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