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Sequence at power on, Prius V not going to ready only shifts to neutral

Discussion in 'Prius v Main Forum' started by ZeroM8, Oct 10, 2023.

  1. ZeroM8

    ZeroM8 Junior Member

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    Hello all,

    My Prius V just had a transmission change (transmission shaft broke due to broken springs in the clutch/damper).

    Long story short, I bought a tranny and clutch/damper, and my mechanic installed it.

    Now it's throwing code P0335 same as before, but the difference is that before, I could hear some kind of noise, as if something is spinning on power up but obviously with a broken shaft, the engine can't spin

    But not anymore now, so it seems to me that the same code shows up because the the crankshaft position sensor isn't even sending a signal to ECU, because the engine isn't even spinning.

    So my question is: what's the initialization sequence? Is it like this?

    *at power up, HV batt sends ~200V to inverter
    *inverter produces 3 phase to MG2
    *MG2 spins
    *crankshaft sensor sends signal to ECU
    *ECU says everything is fine
    *now i can shift the gears

    I know this sequence I summarized isn't everything but I am just trying to narrow down the issue to this code P0335, as to my analysis, the motor is not even initially spinning, as was before the tranny change.

    Some of the things I've/we've done so far on top of the tranny/clutch damper change:

    * new crankshaft position sensor
    *boosted 12V battery, showing 13.7V, same issue
    *my mechanic checked all connections, there's nothing seems out of ordinary
    *I used Torque andoid app with Elm Bluetooth to see if the HV battery is dead, and it shows ~47% charge remaining (also showing 2 bars on dash, so seems in agreement), although I haven't actually measured the voltage as I need to open the battery pack - this will be my next move
    *I ensured the orange jumper is installed properly, i. e. push in, slide to the right
    *my mechanic can spin the engine manually

    Some more questions:
    * i do not suspect the transmission assy which houses the MG1 and MG2 is defective, and I am in denial that that's possible because i know the work involved of changing it again, so my question is, how do a i test that both motors are good? Can I ohm the three terminals out to see if the motors are bad?

    * how do i test if the inverter is functioning as it should, is there a specific voltage at its output and how much?

    If some of these blurbs don't make any sense please do steer me in the right direction. I am tempted to use techstream but last time I tried, it's such a hassle to get it working and just waste too much time. I kind if regretted getting this work done as it involves too much work, on top of my day job, but here's to hoping all is not hopeless, I'm sure a lot of experts here can at least provide some valuable information.
     
  2. ChapmanF

    ChapmanF Senior Member

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    That's sort of a not-bad overview, except you meant MG1. There is no way for MG2 to spin without the car moving, so to start the engine while the car is stationary, MG1 is used.

    Starting the engine is kind of more steps than that. The ECM definitely has to see the crankshaft and camshaft signals, because it has to know when to inject the fuel and spark the plugs. And the power management control ECU is going to look for that magic moment where instead of putting electrical power into MG1, it is getting electrical power back out because now the engine's making more power than needed to twirl it. That's when you can officially say the engine is started.

    Normally, though, the car is happy to let you shift into gear and even drive away before it has started the engine. If it is not letting you shift, dollars to doughnuts there is a problem it has noticed where the fail-safe action for that problem is "don't let the human shift into gear".

    Is the triangle light on? What are you using to read trouble codes? A story like this comes up now and then when someone is using a scan tool that can't get codes from the power management control ECU, and it's probably the codes in that ECU that will explain why it is saying "nope" about shifting.
     
  3. ZeroM8

    ZeroM8 Junior Member

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    I stand corrected, so it is indeed MG1 that spins the engine at start.

    There is no red triangle, but a yellow car symbol with exclamation mark, a red battery symbol for the 12V, a blinking park light when shift is attempted among other lights, but I think these are the relevant ones.

    As mentioned I use Torque, a mobile app in tandem with an Elm bluetooth OBD reader, I undestand its not very extensive but that is what I have now.

    You're right, the ECM doesn't see any signal from the crankshaft (or camshaft) as I mentioned earlier I don't hear any attempt for the system to spin as before the tranny/clutch damper change, isn't this is why the ECM deems it unsafe and refuses to go to ready state for a gear change. No spin therefore no signals from the sensors, no signals from the sensors therefore the ECM doesn't know what to do, please tell me if this is incorrect. But the initial spin has to happen first via MG1, for ECM to see the sensor outputs.

    And therefore code P0335 is thrown.

    If this is the case, where do I start? Inverter? MG1 not spinning? Is the HV battery too low to even spin MG1 at 47% soc? I can measure the HV battery but how can one eliminate the other two, e.g. MG1 or Inverter? Any hints?

    I am reluctant to try and set up a techstream, any easier alternative to pulling out relevant codes?
     
    #3 ZeroM8, Oct 11, 2023
    Last edited: Oct 11, 2023
  4. Brian1954

    Brian1954 Active Member

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    Start by purchasing a better OBD2 scanner, like the Autel AP200 ($50 on Amazon) as reviewed in this thread: https://priuschat.com/index.php?threads/232741/ OR get your TechStream working.

    While you are waiting for the new scanner, you can download an app called "Car Scanner ELM OBD2" and use it with your existing ELM bluetooth adapter to see if it will retrieve more trouble codes.

    Posted via the PriusChat mobile app.
     
  5. ZeroM8

    ZeroM8 Junior Member

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    Thanks, will try those
     
  6. ChapmanF

    ChapmanF Senior Member

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    The ECM does not get to decide about changing gears, or about spinning MG1. The power management control ECU makes those calls. The ECM's job is limited to making the gasoline engine function, when the power management control ECU decides to start it.

    You mean this one?

    mwl.png

    Yeah, that's the light that tells you there are codes in the power management control ECU. It was a red triangle in Gen 1 and Gen 2, and a yellow triangle in Gen 3 liftbacks, and here in the v owner's manual it's the guillotine-car thing. I don't know why they couldn't settle on one shape or color, but whatever, that's the light most of us mean when we say "the triangle".

    Anyway, the codes in the power management control ECU will be the ones that tell you why it is deciding not to start the engine or shift into gear.

    Techstream is one way of reading those codes, but there should be other scan tools that can do it, with some shopping around.
     
  7. ZeroM8

    ZeroM8 Junior Member

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    I will try other readers which may be easier for me to access, as suggested by Brian1954, and see where that takes me, otherwise I may just have to go this route
     
  8. rjparker

    rjparker Tu Humilde Sirviente

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    Did the transaxle come from another Prius v?
     
  9. ZeroM8

    ZeroM8 Junior Member

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    Yes, mine is 2012, the tranny was from 2014 if I remember correctly, but definitely a Gen 3
     
  10. rjparker

    rjparker Tu Humilde Sirviente

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    Good. A v transaxle is different than one from a hatchback gen3.
     
  11. ZeroM8

    ZeroM8 Junior Member

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    Was able to pull out more codes with Dr Prius and veepeak obdcheck VP11.

    Hybrid battery look good, around 208 V, so I think thay van be ruled out.

    Here are the codes:
    P0A09, P0A0D, U0110

    * the 09 is about a bad inverter so thats a consideration

    * the 0D is the orange plug, i can rule that out

    * the U0110 is about a failed comm ? is this related to the failed inverter if that is the case?

    Further, my main issue is that there is a low sound, like a small pump or motor constantly running when the 12V battery is connected. I hear in the engine bay around the inverter area, or below it, even with power off. I had to disconnect the 12v battery for it to go away. I know there's a sound from a pump when power is turned off for the heated coolant to go into the expansion tank, but this doesn't feel like it. Some short? But where to start?

    No P0A08, but I did check all the fuses in the engine bay, nothing's blown.
     
  12. ChapmanF

    ChapmanF Senior Member

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    When you say "I can rule that out", what do you mean?

    If the ECU is showing you P0A0D, there is a lack of electrical continuity through the safety interlock circuit, which runs from the power management control ECU, to the inverter, through some safety contacts beneath the inverter terminal covers, back to the rear of the car, through the safety contacts of the orange plug, and finally to body ground.

    If "I can rule that out" means "got it, I'll go check that circuit now and see what I can rule out", that could accelerate progress.

    If "I can rule that out" means "I've already ruled that out in my head because I think the plug's ok so the ECU must be making things up", that could delay progress. :)
     
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  13. ZeroM8

    ZeroM8 Junior Member

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    Hi Chapman,

    My apologies for being so quick to conclude, yes indeed there are many things to check before we can rule out P0A0D, and not just the orange connector.

    I am still busy working on it, will update later.

    Also with Dr Prius, what would be the typical charging voltage while the system is charging, what is the highest level?

    I am seeing up to 230v but the soc is not going up?
     
    #13 ZeroM8, Oct 14, 2023
    Last edited: Oct 14, 2023
  14. rjparker

    rjparker Tu Humilde Sirviente

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    You have to drive it to get the soc up or use the Dr Prius force charge test. At “idle” it stays low.
     
  15. ZeroM8

    ZeroM8 Junior Member

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    ok seems, the new tranny is working

    the main issue was that big connector from the fuse block into the left side of the Inverter was loose, its a big muti-pin connector and is divided into two segments; my mechanic broke the locking pin, so he did a not so great fix that didn't work

    we took it out after I checked all fuses were working

    so we removed the air filter assembly and
    removed the inverter connector, it didn't feel like it was making contact, because like the HV orange locking plug, you need to pull the locking arm up (the grey part of the connector), push the connector in, and push the locking arm (the grey part i just mentioned, which has two plastic ends that locks in place, unfortunately it was broken)

    the car then started and went to ready mode after pushing the power button twice, but still the dash was lit like Christmas tree, multiple codes came up: P0335, P0343, P0102, P0113, tried clearing, it keeps coming back.

    the dash had a steering wheel with exclamation symbol, traction control symbol, circle with exclamation in the middle in yellow, among others that i think were trivial, such as parking brake, etc

    so there's was quite a bit of fear as to "what is still going on here?" as they wont clear at all after several tries

    on top of this, there's still this constant sound of motor whirring under the engine, and i started measuring the current from the 12v battery and it was over 10 Amps, and my 10 Amps meter goes into overload, and the battery quickly drains to approx 6 volts- this is with the car off. At times the current drops to 7.5Amps, so we thought there's a big short somewhere!?

    this last part above is probably the worst part of not knowing what's going on, i feared theres a big short somewhere (?)

    and why is this happening at a very low 12V battery? i hooked up a battery booster and it refuses to work (batt booster must have protection)

    what's causing this high current draw when the 12v battery is very low? is there a relay somewhere that is enabled/disabled turning on a circuit somewhere?
     
  16. ChapmanF

    ChapmanF Senior Member

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    There's a big whirring noise, under the engine, all the time? When the car is turned off?

    What fuse makes it stop, when pulled?
     
  17. rjparker

    rjparker Tu Humilde Sirviente

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    You need a 10 amp or better charger to keep up with this “parasitic” draw without quickly draining the battery. I would not pull fuses with the system in Ready.

    Odds are good you have some bent pins in one of the many connectors that were removed.

    I would get a piece of hose and find the noise source. Not many 12v suspects: one of the two water pumps or maybe the brake booster pump. Perhaps a radiator fan but not seeing that would be embarrassing.

    An advanced parasitic draw diagnostic technique uses a voltmeter in a millivolt (mv) range across each fuse with the system off. A 7.5-10 amp draw through a fuse will show a high mv reading.

    Or go old school and pull fuses one at a time BUT replace each before going to the next to avoid fuses in the wrong slot.

    Either way, finding the fuse just defines the problem circuit. Then you break out drawings and find the problem.
     
  18. ZeroM8

    ZeroM8 Junior Member

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    I tried the ignition 3 fuse but it doesn't stop. I have to disconnect the 12V batt.
     
  19. ZeroM8

    ZeroM8 Junior Member

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    I tried the ignition 3 fuse but it doesn't stop. I have to disconnect the 12V batt.
     
  20. ZeroM8

    ZeroM8 Junior Member

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    Good idea, never thought of that, I always use the meter in series but this is simpler/better.