2012 Prius refused to Start. Error Code P0335 – Crankshaft Position Sensor A Circuit Malfunction

Discussion in 'Gen 3 Prius Technical Discussion' started by Chuba, Sep 15, 2021.

  1. Chuba

    Chuba Junior Member

    Joined:
    Aug 18, 2019
    45
    4
    0
    Location:
    Nigeria
    Vehicle:
    2012 Prius
    Model:
    Two
    Good day every one.

    My 2012 prius stopped me on the road. It's having 140,000 miles on it. I scanned it and I'm getting P0335 crankshaft position sensor A circuit and P0A0F.
    I have changed the crankshaft sensor still the engine refused to start. The wiring harness has been traced to the brain box and it shows there is no damage to the wiring harness. We opened the engine and checked the crankshaft reluctor wheel and it's in good condition. The timing is also good.
    Still the car refused to start.
    The car only drive on HV battery but the engine will not start.
    Before now I was having rattling and knocking noise. When ever it's idea or moving at low speed with the HV battery being charged. If I speed the rattling noise stops. I do not lose power. Which I was yet to find out the issue.

    Please what else can I check to resolve this P0335?
    Is Changing the engine and transaxle solve this issue or could it be bad brain box?

    Please solution needed.

    Thank you.
     
  2. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    14,261
    10,074
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    The players in that game are the crankshaft position sensor, the wiring and connections from there to the ECM, and the ECM itself.

    If you're sure the sensor and the wiring and connections have no problems, the ECM is what's left.

    However ... it is not at all common for ECUs to fail. That could be a reason to review carefully what steps you used to become convinced the wiring and connections and the replaced sensor are definitely good, before condemning the ECM.

    Are you able to crank the engine over by using a power tool on the crank bolt, for example? If you attach a scope at the sensor wires where they meet the ECM, do you see the expected waveform?
     
  3. Chuba

    Chuba Junior Member

    Joined:
    Aug 18, 2019
    45
    4
    0
    Location:
    Nigeria
    Vehicle:
    2012 Prius
    Model:
    Two
    Yes Sir, I'm able to turn the engine but we didn't read any thing while turning it. We only turned it to check if the engine is knocked.
    We also changed the gasket because of the knocking and rattling noise I was hearing before.


    Note
    If I clear the error code and push the start button. The ready light comes on and I will hear some sound inside the transaxle may be trying to start the engine. After like continues 5 seconds of the engine not starting the check hybrid and check engine light comes back on the dash and the transaxle noise stops. The ready light stays on and the car will only drive on electric.
     
  4. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    14,261
    10,074
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    You reported a P0335 code, which is a certain indication that either (1) the crankshaft sensor signal isn't properly reaching the ECM, or (2) a proper signal is reaching the ECM but the ECM thinks it is not proper (which would make the ECM at fault).

    An oscilloscope at the ECM connector where the crankshaft sensor wires arrive would be about the most definitive way to distinguish (1) from (2). If the signal is poor, you can concentrate on what is wrong with the sensor or wiring to make it poor, or if the signal is good, you can conclude the ECM is at fault.
     
  5. mr_guy_mann

    mr_guy_mann Active Member

    Joined:
    Sep 3, 2020
    962
    410
    0
    Location:
    NJ-USA
    Vehicle:
    2006 Prius
    Model:
    Four
    I would suggest unplugging the ECM connector that has the wires for the cam and crank sensors. Then carefully back probe each circuit (from the wire side, not the terminal side that goes towards the ECM) and test resistance for both sensors (see the service manual for specs)- and check for any resistance to ground (should be infinite resistance).

    If that checks out ok then you may need to have someone with a 2 channel scope test both sensors to see if they can put out correct signals and that the signals are in the proper relation to each other (aka- correct cam timing or "sync").

    Sometimes a bad sensor can fool the ECM into coding the "good" sensor- as can a cam that's out of time. IF you can verify that both signals are correct and sync is correct THEN I might consider the possibilty of a bad ECM (after load testing all ECM power and ground circuits).

    Posted via the PriusChat mobile app.
     
  6. JamiFids

    JamiFids New Member

    Joined:
    Sep 14, 2021
    7
    1
    0
    Location:
    USA
    Vehicle:
    2010 Prius
    Model:
    Four Touring
    I recommend that you contact an electrician. You may have a malfunctioning sensor.
     
  7. Chuba

    Chuba Junior Member

    Joined:
    Aug 18, 2019
    45
    4
    0
    Location:
    Nigeria
    Vehicle:
    2012 Prius
    Model:
    Two
    Things done so far.
    I have
    1. Tested the crankshaft position sensor and its within Toyota specified range. Which means sensor is OK.
    2. I have changed the Crankshaft Position Sensor,
    3. I changed top gasket
    4. I inspected the crankshaft reluctor wheel and it's OK and well seated in its position.
    5. Timing chain inspected and it OK.
    6. Finally I have changed the ECU or brainbox

    So after changing the ECU or brainbox the car did not still start. If I start it, ready mode comes on and I will hear sound that sound like the brake pumps pumping from the engine side then the check hybrid system light and check engine light comes on and then the sound stops.

    The car can drive on EV mode only. The engine does not start.

    Pls note: this car was having knocking and rattling noise before this whole thing happened.

    I will like to know what kicks the engine. I kind of think that will be my problem.
    If I can change that which kicks or starts the engine I kind of feel the car will start.
     
  8. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    14,261
    10,074
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    What are the trouble codes that now appear, after your most recent changes? That's the first important information to get.

    What starts the engine is the motor-generator MG1, located inside the transmission. It is difficult to access. More to the point, there might not be much reason to suspect it, at least not before knowing the most current trouble codes.
     
  9. Chuba

    Chuba Junior Member

    Joined:
    Aug 18, 2019
    45
    4
    0
    Location:
    Nigeria
    Vehicle:
    2012 Prius
    Model:
    Two
    The old codes are what I still have.
    Which are P0335 crankshaft position sensor and P0A0F.
    There were no codes when the engine was rattling and knocking.

    I'm now considering changing both the engine and transaxle
     
  10. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    14,261
    10,074
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    Have you made any effort to rotate the crankshaft (by hand, with an assistant, or with a power tool) while observing the crankshaft sensor signal at the ECM connector with an oscilloscope?

    I see that you have posted this:

    ... by which I suppose you mean that you tested the sensor with an ohmmeter. So it was in the specified resistance range, which does make a sensor issue look less probable.

    On the other hand, you now have two different ECMs agreeing that there is an issue with the sensor signal.

    That could be a good reason to go further and view the sensor signal on a scope while the crank turns, as mr_guy_mann suggested in #5.

    "whatever remains, however improbable, must be the truth."
     
Loading...