2004 Prius won’t start up. Died while driving. Warning lights blink then shut off.

Discussion in 'Gen 2 Prius Technical Discussion' started by Bob!, Dec 29, 2022.

  1. Bob!

    Bob! Junior Member

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    Suddenly, my 2004 Prius won’t start up. Died while driving.

    When I hit the Power button, the warning lights blink and then shut off. The squares around the gears (R, P, D, B) on the display blink after the other lights turn off. When I hit the Power button the light on it is amber and it blinks 8 times and then the 9th blink is like a half blink. The Power button blinking starts when I hit the Power button and continues even after all the other lights are off (including the illuminated gear squares).



    2004 Prius
    HV battery replaced a 221 miles ago
    12v battery new from Toyota in November
    250,000+ miles

    I did a voltage test using the screen on the vehicle and the diagnostics page and it’s at 12.3 volts. The car died while I was driving and made no indication of a 12 volt failure before it died (dimming lights, warning lights, etc.), it just straight up died.

    When I enter auxiliary mode, the monitor screen lights up and the radio and clock work, but when I hit the Power button again in an attempt to start it, the display lights blink as described above and everything shuts down (including the monitor screen w/ radio, clock).

    At this point, I decided to disconnect the HV battery and repeat the above steps. I found that the vehicle did exactly the same things as mentioned above: quick flash of display, blinking boxes, car doesn’t start. So the vehicle is failing in the exact same way when the HV is connected and disconnected.

    I spoke with the technician at the company who replaced the battery and they said it’s not likely that the problem is the HV as the system is not firing up long enough to cycle through to the point of access the HV battery.

    Perhaps there was an issue with the communication between the vehicle and the HV battery?

    Could it be that I have an ECU/PCM problem? A problem with the Body Control Unit?

    If any of y’all have any suggestions on what I can do to figure this out and fix it, please let me know. I hope to get this car back up and running as I love that li’l thing. Thanks for your help with this matter.

    Thanks in advance,
    -Bob
     
  2. Tombukt2

    Tombukt2 Senior Member

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    The first thing sounds like you need to have somebody with tech scan the car or with a capable scanner that can scan like tech which may take you longer to find than just going to somebody with tech and having that done Don't know how much of a gun you're under. Without the proper scans you're really barking up trees all day long that you have no idea what's up there. With these particular cars and the 17 to 21 computers or whatever goes on here you need to have an accurate scan accurate and capable scan without it You may be here for a month that will give you a ballpark area to look at seems like a relay or something's not working correctly because you're not even getting halfway to ready seems like the eight blinks would mean something but I don't have a factory manual to tell you that or even the page numbers you need to look at One of the guys who studies this stuff all the time will maybe come along and tell you what the eight blinks means I've never seen such a thing but I would imagine like any other electronic component that blinking is trying to tell you something and it's always eight blinks and a half or what have you?
     
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  3. Bob!

    Bob! Junior Member

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    FWIW, I found this other thread where the OP had similar, if not identical, problems:

    Prius won't start, flashes the combination meter for a split second | PriusChat

    The thread was abandoned without a stated resolution, so I started this thread. I also went ahead and posted over on the other thread in an attempt to revive it.

    It's ALIVE! The other thread. OP came back and posted that the fix for them was replacing the ECU. I've been suspecting that this is the problem and will give it a shot. Will update when I finish the swap.
     
  4. bisco

    bisco cookie crumbler

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    good luck!
     
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  5. mr_guy_mann

    mr_guy_mann Senior Member

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    Have you tried scanning the car for codes? If you use a capable scantool, then finding what ecu's do or do not respond plus any codes will give you a direction.

    Posted via the PriusChat mobile app.
     
  6. Bob!

    Bob! Junior Member

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    I have, but it won't scan in Aux mode and won't turn on long enough to scan otherwise.
     
  7. vvillovv

    vvillovv Senior Member

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    some of the apps / bluetooth adaper for the ODB2 port will work partially in AUX mode. drprius, car scanner, hybrid assistant apps .... Kinda hard to learn new apps while trying to diagnose an issue without much info to work with from the start.
     
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  8. dolj

    dolj Senior Member

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    Generally, no it won't. It has to be in IG-ON mode, i. e. two presses of the Power button without your foot on the brake pedal. ACC mode is one press of the Power button without your foot on the brake pedal.
     
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  9. Bob!

    Bob! Junior Member

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    When I hit the button a second time (w/out foot on brake) it turns on and off again in the way described above. Same as when I do have my foot on the brake and press the Power button.
     
  10. Bob!

    Bob! Junior Member

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    Well, that wasn’t the problem. Or wasn’t it?

    I bought a used ECU from eBay and put it in today. The car turns on for a split second and then back off, as described in the original post.

    So, either the ECU wasn’t the problem (and I, once again have no idea what the problem is) or the used ECU I bought is broken in the same way.

    It might seem unlikely that the used eBay ECU failed in the same way as the original but I did once buy a used ABS actuator for a Gen 1 Prius and put it in (huge pain in the rear) only to learn that it did not work at all and wouldn’t even power up. So, it happens… ugh.

    If anyone has any ideas or suggestions, I’d appreciate it.

    Thanks.
     
    #10 Bob!, Jan 3, 2023
    Last edited: Jan 3, 2023
  11. vvillovv

    vvillovv Senior Member

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    I normally wouldn't recommend this since it will clear a lot of stuff I wouldn't want to loose. You could try the ole go to move of removing the negative terminal from the 12 volt. But checking your fuses first might be better to start with.
    If trying the negative terminal removal, I'd start with a few seconds off, than reclamp it back on. If no change, I might disconnect it for a longer time.
    Your call, there might be other things I'd try first if I were actually looking at the car in person, Ya know the internet thing can work wonders at times, or times not so much.
     
  12. mr_guy_mann

    mr_guy_mann Senior Member

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    I would scan the car in accessory mode. Using a capable scantool on my 06, I could talk to A/C, immobilizer, power source control, smart key, TPMS, gateway, and BCM. Any codes there might give you some clues.

    Also, I would unplug the inverter coolant pump (there's a single wire connector -white with black- right behind the underhood fuse block on the left strut tower), then check (or just replace) the AM2 fuse (in the underhood fuse block). Usually a fault here will pop that fuse, but it's still worth checking.

    Beyond that you would have to do some "advanced" electrical testing to see if the power feeds to the ignition relays are good, as well as the relays themselves.

    Posted via the PriusChat mobile app.
     
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  13. Bob!

    Bob! Junior Member

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    Well, what do ya know?

    I checked the AM2 fuse and it’s blown. Swapped the fuse and unplugged the inverter coolant pump and it started right up. Plugged the inverter coolant pump back in and started it up. Started smelling burny and smoke wafted up from the inverter coolant pump. Turned it off and ordered a new inverter coolant pump. Sounds like this was the problem all along. Ill update when I get the new inverter coolant pump in there.

    Thanks a bunch for the tip, mr_guy_mann!
     
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  14. mr_guy_mann

    mr_guy_mann Senior Member

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    You're welcome.

    Be sure to completely bleed the inverter cooling system - I use a length of clear tubing from the bleeder screw back to the tank filler. Might want to "fully" drain the system and refill with fresh. Can take several minutes of run time to get all thr air out, depending on how much is drained.

    Posted via the PriusChat mobile app.
     
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