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C1365 After Brake Actuator Replacement?

Discussion in 'Gen 2 Prius Technical Discussion' started by Jimmy422, Mar 19, 2023.

  1. Jimmy422

    Jimmy422 New Member

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    I just replaced the brake actuator in my 2008 Toyota Prius. I completed the techstream process for bleeding the brakes as well as running the linear offset calibration and yaw calibration. Everything is okay after calibration and bleeding is complete. I had driven nearly 200 miles with no issue after replacement.

    However, today I got a C1365/54 (detailed code 215) error, a loud constant beep, and poor brakes. I have re-run the bleed (there was no air in any of the lines) and the calibrations with everything going back to normal after doing so and cleaning codes, but the same issue returns after shutting the car off and turning it back on. I don’t see any leaks anywhere and like I said, everything feels okay while the issue isn’t occurring. I also validated the connector on the ABS module is clean with contact cleaner and is clipped on all the way.

    Does anyone have any advice? I have no idea what else to check at this point.
     
  2. mr_guy_mann

    mr_guy_mann Senior Member

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    That code indicates that the brake ecu doesn't like something about the accumulator pressure signal (PACC ckt). The description for INF 215 is kinda vague to me (a non-engineer). "The ratio of PACC to VCM1 (5V reference) is less than 90.5% for at least 0.1sec during self diagnosis".

    Follow the diagnostic procedure in the service manual. It has you checking the PACC voltage directly with a DVOM, and on the scantool (Acc Press sensor 1). - what does the scantool show for that? (Normal on my 06 is turns on around 3.2V, and turns off at 3.6V)

    I don't know if you will need a scope to catch any fast glitches.

    What was the reason for replacing the brake unit? Where did you get the part?

    Posted via the PriusChat mobile app.
     
  3. SFO

    SFO Senior Member

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  4. ChapmanF

    ChapmanF Senior Member

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    That is something of a puzzler. A glance upward at INF 212 suggests that the normal range for PACC (relative to the 5 volt reference supply) is to be always above 5% and always below 90.5%.

    And yet INF 215 is complaining about PACC not being above 90.5%. The "during self-diagnosis" must be key; there apparently is a self-diagnosis routine that tries to push the signal above the 90.5% threshold for test purposes, and complains if it can't.

    Whether it tries to push the signal that high by pumping an actual extra high fluid pressure, or by electrically changing the impedance of the input, I'm not seeing. The description for INF 216 does suggest some impedance games can be played.
     
  5. Jimmy422

    Jimmy422 New Member

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    Okay, so I got a chance to take a look at everything today. Here are the results according to the diagnostic flowchart for that code:

    1b:
    Expected - Actual
    Below 1ohm - 0.7ohm
    Below 1ohm - 0.7ohm
    Below 1ohm - 0.7ohm
    Below 1ohm - 0.7ohm

    1c:
    Expected - Actual
    Above 10kohm - Above 10kohm
    Above 10kohm - Above 10kohm
    Above 10kohm - Above 10kohm
    Above 10kohm - Above 10kohm

    2a:
    Expected - Actual
    4.75v to 5.25v - 5.00v

    3a:
    Expected - Actual
    10v to 14v - 12.35v

    3c:
    Expected - Actual
    3.3v to 4.7v - 4.23v

    4c:
    Expected - Actual
    3.2v to 4.0v - 4.23v and did not drop

    ---

    So I'm a little confused on 4c. It says the range is 0v to 5v and I was measuring 4.23, which is in spec, but not between 3.2 and 4.0. Is that bad or expected?

    If that's bad, that means it's the brake actuator. If not, that means it's the skid control ECU I assume.
     
  6. Jimmy422

    Jimmy422 New Member

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    I replaced the actuator because the seller of the car got the diagnosis of a bad actuator from a Toyota dealership. I got the part brand new from a local toyota dealership parts department. I also replaced the resistor under the dash when I did the replacement.
     
  7. mr_guy_mann

    mr_guy_mann Senior Member

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    Does the pump motor turn on after pressing the brake pedal a few times? Does the pump turn off?
    When you check PACC voltage with a meter, does that voltage change at all when pressing the brake pedal?

    I would measure E/E1 voltage (should be ground (0V) , as well as PCK1 (no idea what that is but see what you have).

    The "range" for PACC is what the scantool can display for that data (something from 0 to 5V). Under the test conditions, the ecu expects 3.2 to 4.0V. Anything that is outside of what's expected will set codes.

    (I assume) The ecu supplies 5V (VCM1) and ground ("0V") to a three wire pressure sensor. That sensor should return a signal that is proportional to the pressure detected at the accumulator. That signal voltage cannot go higher than 5V, and cannot go lower than 0V. The sensor itself might only be capable of a smaller range.

    If PACC voltage never changes, you will want to unplug the actuator connector then see what PACC voltage (direct measurement) and scan data is. That would likely be a faulty new (sensor inside the) actuator assembly, but you should double check all possibilities first.

    Posted via the PriusChat mobile app.
     
  8. Jimmy422

    Jimmy422 New Member

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    I ended up taking it to the dealership. They diagnosed the issue as a faulty actuator, as well as “corroded grounds on ground points related to the braking system”. Awfully vague, but whatever. They replaced the actuator and cleaned the grounds and it’s been good for 120 miles so far. I’ll update if anything happens again. I hope not, after paying almost $2000 in labor
     
  9. dolj

    dolj Senior Member

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    It doesn't sound awfully vague to me. $2000 in labor - yikes! How many hours was that?

    All the best and I hope your troubles are over for now.
     
  10. Jimmy422

    Jimmy422 New Member

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    I think it was 8 hours of labor? They had the car for 3 weeks trying to figure out the grounding issue though. So that makes me feel like I got my money’s worth, at least. Haha.

    The car only has 61,000 miles on it so I expect to get lots of life out of this baby. Thankfully the seller lowered the price by $3000 when I bought it because of the ABS actuator issue, so I’m not too screwed by the price I paid.