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2003 Prius, P3125 code & drivability issues

Discussion in 'Generation 1 Prius Discussion' started by Hinoserm, Jul 22, 2014.

  1. Hinoserm

    Hinoserm Junior Member

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    Hello,

    I have a 2003 Toyota Prius with ~250,000 miles. Yesterday I was driving and the vehicle started to "stutter" and the warning lights came on. My ScanGauge indicated code P3125. I drove normally for 2-3 miles and parked for a bit. When I returned, I was able to start up and drive home with no problems (about 20 miles of highway and stop & go traffic), and drove most of this morning, but around noon it happened again and this time the vehicle would hardly move at all. It had no reverse and I had to push it out of the parking spot. I managed to limp home and park it.

    After a few hours, I started it back up. The engine starts without any hesitation, but it still wouldn't give me any power in forward or reverse. I left it running, opened the hood and started banging around (literally) on the inverter and the HV wiring. That appears to have immediately fixed it; I was able to pull out with the still-running car and drive around several blocks and return without issue. Using the scanguage to read the inverter and transmission temperatures, everything has been typical (120-160 degrees Fahrenheit). Battery state-of-charge PID indicates that it is charging and discharging during the times the vehicle is able to move, hovering between 50-60% (typical for my vehicle). I can see no physical signs of damage or loose connections on the HV wiring, and the inverter cooling pump was replaced not very long ago (and appears to be working).

    I'm waiting to get access to a Techstream unit so I can see if there are additional codes. Is it possible to get the codes from the MFD? Can someone offer insight as to what I could expect?

    Thank you.
    -Michael
     
  2. ChapmanF

    ChapmanF Senior Member

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    Hi Michael,

    Each basic trouble code like P3125 can have up to three (IIRC) three-digit "INF codes", and you can find XGAUGE definitions allowing your ScanGauge to pull those. They really add a lot of information to the basic trouble code, which can be very generic on its own. Volume 1 in the shop manual has many pages detailing what the system is telling you based on the trouble code and the INF codes.

    -Chap
     
  3. Hinoserm

    Hinoserm Junior Member

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    I've been looking for but can't seem to find the XGAUGE values. I keep running into a supposed database but the data is not in any context that I understand.

    Is a download available for that manual?

    -Michael
     
  4. ChapmanF

    ChapmanF Senior Member

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    techinfo.toyota.com is your online source for all the service literature.

    Try here for a spreadsheet where the PID database is pre-munged into ScanGauge XGAUGE code. Look for the entries with names ic1, ic2, ic3, ic4, ic5.

    -Chap
     
  5. Hinoserm

    Hinoserm Junior Member

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    Awesome, thank you!

    From the scangauge IC1 = 302 and IC2 = 300, which if I'm reading correctly indicates a problem with the "Motor inverter current sensor".

    Techstream shows 297, which also indicates a problem with the current sensor.

    Is this sensor located inside the inverter? Is it likely to be repairable?

    EDIT: Techstream seems to indicate I also have codes C1202 C1259 and B0101.

    -Michael
     
  6. ChapmanF

    ChapmanF Senior Member

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    The brake and HV ECUs keep in close touch with each other, and C1259 is nothing but a brake ECU code that means "HV ECU has told me some kind of trouble over there". It's clearable as soon as the actual HV ECU issues are fixed.

    I think the current sensor's in the inverter, and the inverter's intended as a field-replaced unit. If you have EE proclivities and want to tear into it, you could perhaps do more. You can search for 'hobbit's pictorial post of an old inverter he tore down step by step. I think it was a Gen 2, but you'd get the idea.

    -Chap
     
  7. ericbecky

    ericbecky Hybrid Battery Hero

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    There has yet to be a great documented repair guide for the inverter.
    Even if you could visually find a problem, you may not be able to actually repair it.

    If you don't want to buy new, I recommend getting one from a reputable salvage yard that provides a warranty.
     
  8. Hinoserm

    Hinoserm Junior Member

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    I'm going to pull my inverter apart tonight and see if I can diagnose it a little better.

    I've come to learn there are at least two versions of inverter assembly for this vehicle; G9200-47070 and G9200-47071.

    Mine is 47071, but I can only seem to find the 47070 model at reasonable prices. There are several salvage yards with the older model available for <$200, but the newer ones I've found are $800+.

    I can't afford to spend hundreds of dollars and I'm not looking for perfect performance. How bad would it be to use the older inverter in place of mine?

    -Michael
     
  9. Hinoserm

    Hinoserm Junior Member

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    Turns out the sticker on the inverter says it's the 47070 model. I was going off the service record which shows they replaced it in 2008 and has a note with the G9200-47071 code. I'm guessing it was a typo. I'll order the salvage inverter and between the two of them hopefully I can get back up and running.

    -Michael
     
  10. bwilson4web

    bwilson4web BMW i3 and Model 3

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    Always good to 'reseat the connectors'. About 99.9% of the time, it doesn't work but if you're waiting on a part . . . what is time?

    Bob Wilson
     
  11. Hinoserm

    Hinoserm Junior Member

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    Where is the HV ECU located on the '03? I've reseated everything on the inverter side that I can access without removing it.

    -Michael
     
  12. Hinoserm

    Hinoserm Junior Member

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    Going to wait for the "new" inverter to come in next week before trying to pull the old one out. I've made some interesting observations, though...

    Shortly after I bought the car, I thought I was going crazy. It felt like the car was "moving" while in park, very very slightly rocking back and forth, and it would stop when I applied the brakes. I was able to actually catch it one day and see the wheels moving ever so slightly. I assumed it was just a quirk of the way the Prius is designed.

    I'm wondering if that was an indication that inverter failure was imminent, because it's extremely obvious now. Sitting in place the car visibly and violently rocks forward and back. I can make it stop by giving the inverter a few hard knocks, but after a few seconds it acts up again. It's definitely not vibration from the engine.

    My big concern though, since it's showing a problem with a current sensor... did the current sensor fail, or did something else fail and cause the readings at the current sensor to go far enough out of whack to confuse the rest of the computer. I don't know enough about how the inverter works to understand why the current sensor is vital to the operation of the motors, or why both sensors would suddenly fail.

    The computer seems to indicate both the "main" and "secondary" sensors have invalid readings, but doesn't tell me what exactly that means. Are they two sensors, one each monitoring the two motor coils, or is it two sensors giving redundancy to one reading? If they're separate sensors, did they both fail at the same time? I found one of the current sensor assemblies, but can't get access to it. The other one is buried deep inside the inverter.

    -Michael
     

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