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GEN 1 prius P3106 powertrain code and vehicle stalls

Discussion in 'Generation 1 Prius Discussion' started by blake9809, Jul 8, 2024.

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  1. ChapmanF

    ChapmanF Senior Member

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    Toyota's opinion should probably be represented in the thread too (whether or not anyone thinks it's the last word): the check in the gen 1 repair manual (2001 edition, page DI-8, "BASIC INSPECTION", step 1) is "Is the battery positive voltage 11 V or more", and you "charge or replace battery" if it isn't. I'm pretty sure that's the same threshold as in the later repair manuals.

    There are several ECUs in the car that measure their own supply voltages and can give trouble codes if they measure low. The C1241 code from the brake ECU is one example. The thresholds for those codes generally fall in the 8.5 to 9.5 volt range. Remembering, of course, those aren't readings of the battery under no load, but actual voltages seen in operation when a load may be pulling it down.

    Certainly it's never a bad idea to check the battery voltage, and in particular if you have any of the voltage-based trouble codes, it becomes an even better idea.

    Back when I had a gen 1, it typically started ok down to 9 volts or a little less; it would, of course, log the voltage-related codes, but didn't go 'haywire' or present bogus codes or anything. Below 8 volts I'd more often need to jump it or swap in my spare battery, but again there'd be no weirdness after. I had a fair amount of experience with that, as I usually had some half-baked mod project or other in the works and ran down my 12-volt battery more times than I'd have liked.
     
    #21 ChapmanF, Jul 26, 2024
  2. blake9809

    blake9809 Junior Member

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    so the EFI relay and fuse were bad. Replaced the EFI fuse and relay under the hood. Car fired right up and idled for a solid 2 minutes and then some magical electrical smoke came from under the hood, car died and got the exclamation mark on the dash. Examined the wires and a wire in the main wiring harness on top of the engine has lost all of its insulation and is a bare copper wire now. Will need to follow this wire through its whole path and replace the one wire, must be a direct short some where.
     
    #22 blake9809, Aug 7, 2024
  3. ChapmanF

    ChapmanF Senior Member

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    Is there enough insulation left visible for you to tell what color it was?
     
    #23 ChapmanF, Aug 7, 2024
  4. blake9809

    blake9809 Junior Member

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    No its just a bare copper wire now, lol. the insulation is all black. I am going to pull the wiring harness apart and follow the wire in a week or so when i get some spare time. Will update back with what i find
     
    #24 blake9809, Aug 9, 2024
  5. blake9809

    blake9809 Junior Member

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    It appears to be two wires and they are solid black color. Have not had enough time to fully remove the harness and locate exactly where the wires go but will keep at it.


     
    #25 blake9809, Aug 12, 2024
  6. ronlewis

    ronlewis Active Member

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    Dang, I've been gone. Did I ever send you the electrical manual? Sorry for the delay.
     
    #26 ronlewis, Aug 13, 2024
  7. MAX2

    MAX2 Member

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    According to the diagram, the black wires from the relay EFI and fuse also go to the sensors located on the catalyst.
    After the catalyst was stolen, were the remaining wires insulated and plugged?
    Free movement wires may cause a short circuit and blown fuse.
    What value of the new fuse was inserted in place of the blown one?
     
    #27 MAX2, Aug 14, 2024
  8. blake9809

    blake9809 Junior Member

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    no never received it but i just purchased the paper toyota manual 1 and 2. i also purchased the digital copy, flipping through it to see what i can find.
     
    #28 blake9809, Aug 15, 2024
  9. blake9809

    blake9809 Junior Member

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    so when i first found that the efi fuse was blowing and the efi relay was defective i suspected the downstream 02 sensor wires since they were cut. So on the passenger side i pealed the carpet back and unplugged the sensor and the wires were just exposed, i was like BINGO seems like the issue might be solved. I put a new relay in and also a new 15 amp fuse. Then i proceeded to start the car and it ran for the 2 minutes but then torched two black wires on the top of the engine in the main wiring harness. So it was odd and the fuse never did blow, i pulled the fuse out and replaced it with a different one. Very good possibility the fuse was defective and never blew. Any ways when i get a free weekend i am going to pull the whole engine wiring harness out of the vehicle, take off all the tape, and see exactly what wires are the problem. Hopefully that can tell me what sensor or what is causing the issue. I purchased a used wiring harness from a junk yard so i can put that back in.
     
    #29 blake9809, Aug 15, 2024
  10. ronlewis

    ronlewis Active Member

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    Well, dang, sorry about that. The hurricane here put me off my routine. Glad you're moving forward.
     
    #30 ronlewis, Aug 16, 2024
  11. blake9809

    blake9809 Junior Member

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    well replacing the full gasoline wiring harness was not that enjoyable. Extremely hard to get to most connectors. Next time im pulling the engine, lol.

    Any ways i pulled the full gasoline wiring harness out and it was the upper oxygen o2 sensor causing the problems. The wires broke right on the sensor itself and the wires grounded out. When i replaced the 15 amp EFI fuse the fuse i inserted was faulty and never tripped when i started the vehicle causing the wires in the harness to melt and cause further problems. Lesson learned always purchase top shelf fuses.

    After getting the harness replaced with a junk yard harness the vehicle starts and runs :) its throwing a upstream o2 sensor code since i have not replaced the sensor yet. plan to get a new o2 sensor installed this week.

    Will the vehicle still drive normally without the upstream o2 sensor or should it get replaced right away?



    PXL_20240915_215308847.MP.jpg
     
    #31 blake9809, Sep 16, 2024 at 11:29 AM
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