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2004 Prius Dead

Discussion in 'Gen 2 Prius Main Forum' started by Richard DeRoberts, Feb 16, 2024.

  1. Richard DeRoberts

    Richard DeRoberts Junior Member

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    2004 Prius
    Model:
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    I have a 2004 Prius with 173,000 miles on it. I went on a 150 mile trip yesterday and it drove fine until it went dead at a light. The red triangle of death came on for 1/2 second and then the dash went blank. When I try to start the car, it shows some lights in the dash and then shows square boxes where the RNDPB letters should display then it goes blank. I can't get any codes from the car. The engine does not start. The windshield wipers move for about 1/2 second but will not continue to their resting point when I try to start the car. The windows will move when I try to start the car if I have a window switch pressed. I tried disconnecting the 12V battery for 1/2 hour with no success. I tried disconnecting the HV battery but still no success. The car's front wheels are locked so the tow truck had to lift the front end for towing. The emergency lights with blink. If I press the start button twice with no brake pressed the multifunction display comes on. I had a maint req light showing with a code for an O2 sensor which I bought and was getting ready to replace.
     
  2. pasadena_commut

    pasadena_commut Senior Member

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    So many possibilities. These are the things I would check first:

    1. 12V battery is at >12V and will hold a charge.
    2. There is still oil in the engine.
    3. There is still coolant in both coolant loops and it is at the right levels.
    4. The air intake path is not blocked.
    5. The MAF sensor is where it should be and looks undamaged.
    6. The wiring harness under the hood isn't obviously chewed up (ie, by rodents).
    7. There is gas in the gas tank. (Can't tell? Put in a gallon slowly.)
     
  3. Richard DeRoberts

    Richard DeRoberts Junior Member

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    I found an interesting video about the engine control computer. 08’ Prius Engine ECU replacement no reflash (youtube.com) The problem was the O2 sensor code with the engine check light being on. Just like mine. Replacing the ECM fixed the problem. I have not done this but it is a lead. I don't know if the ECM can make the dash display show square boxes instead of the RNDPB letters. However, in pushing the start button with the brake depressed repeatedly the RNDPB letters lighted up correctly twice instead of the square boxes.
     
  4. mr_guy_mann

    mr_guy_mann Senior Member

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    Check all the fuses in both fuse boxes.

    Power the car on as far as you can then check all the fuses for 12V power. It sounds like an "ignition" power feed is missing.

    Posted via the PriusChat mobile app.
     
    #4 mr_guy_mann, Feb 17, 2024
    Last edited: Feb 17, 2024
  5. TMR-JWAP

    TMR-JWAP Senior Member

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    The few times I've dealt with a Prius just dying in the middle of a drive, it was the inverter cooling water pump failing and blowing the AM2 fuse in the underhood fuse box.
     
  6. Richard DeRoberts

    Richard DeRoberts Junior Member

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    Yes, It was a blown fuse. #31 "IGN" fuse, ignition system. It's a 15 amp fuse. I replaced it and the dash lit up with the red triangle and the odometer blinking and the fuel gage blinking and all the other lights on or blinking. When I tried to start the car the 15 amp fuse blew again. Any suggestions?
     
  7. Richard DeRoberts

    Richard DeRoberts Junior Member

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    I disconnected the inverter coolant pump wires and replaced the IGN fuse. The car dash is back to normal but has the red triangle and all the mait req lights are on. I assume this is because the car sees that there is no coolant pump attached to the system. The car will go forward and back and the engine starts. I know you can't drive the car very far with no inverter coolant. So now it's time to order a pump and fix the problem.
     
  8. mr_guy_mann

    mr_guy_mann Senior Member

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    You'll want to use a capable scantool to check all systems for codes.

    Until the inverter actually gets "too hot", there won't be any codes. Nothing on the car can detect if the inverter pump is present or not.

    So unplugging the pump by itself can't immediately trigger the master warning light.

    I assume that your 15A "IGN" fuse is the AM2 fuse in the underhood fuse box.

    Posted via the PriusChat mobile app.
     
  9. pasadena_commut

    pasadena_commut Senior Member

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    Depends on the ambient temperature and how fast the car is going. I think one could probably drive around all day at suburban speeds on a flat route if the ambient temperature was 70F or less. Highway driving needs more current, so if the inverter pump is out the inverter will overheat unless maybe it is really, really cold.
     
  10. Richard DeRoberts

    Richard DeRoberts Junior Member

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    Two
    Ok, Fuse #31, 15Amp is called AM2 in the fuse box and IGN on the fuse location documentation I have. The only system code present was P0A1D Hybrid Powertrain Control Module. So, I disconnected the 12V battery for 30 minutes and reconnected it. Now there is no red triangle, and the car comes up READY. The only warning I have now is MAINT REQ light. There is no little yellow engine symbol. That was the warning I had about the number 2 downstream O2 sensor I had long before the car died. There are now no system codes - 0 faults found.
     
  11. mr_guy_mann

    mr_guy_mann Senior Member

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    I expect the O2 sensor code will return after you drive some. The ECM doesn't immediately turn on the sensor heater and so won't check sensor function until it does.

    Posted via the PriusChat mobile app.