AUTOMATIC TRANSMISSION SYSTEM (for 3UR-FE), Diagnostic DTC:P0729

DTC Code DTC Name
P0729 Gear 6 Incorrect Ratio

DESCRIPTION

The ECM uses signals from the output speed sensor SP2 and input speed sensor NT to detect the actual gear position (1st, 2nd, 3rd, 4th, 5th or 6th gear). Then the ECM compares the actual gear with the shift schedule in the ECM memory to detect mechanical problems of the shift solenoid valves, valve body or automatic transmission (clutch, brake or gear, etc.).

DTC Code DTC Detection Condition Trouble Area
P0729
  • 6th gearshift malfunction:

  • The ECM determines there is a malfunction when both of the following conditions are met (1 trip detection logic).

(a) When the ECM directs the transmission to switch to 5th gear, the actual gear is also shifted to 5th.

(b) When the ECM directs the transmission to switch to 6th gear, the actual gear is shifted to 4th.


  • Valve body is blocked up or stuck (sequence valve)

  • Shift solenoid valve SLT remains open or closed

  • Automatic transmission (clutch, brake, gear, etc.)

Tech Tips


  • Gear positions in the event of a solenoid valve mechanical problem:

    ECM command gearshift 1st 2nd 3rd 4th 5th 6th
    Actual gear position under malfunction 1st 2nd 3rd 4th 5th 4th
  • Gear position during fail-safe operation:

    If any malfunction is detected, the ECM changes into the fail-safe mode to shift into the gear positions as shown in the table below.

    Gear position under normal conditions 1st 2nd 3rd 4th 5th 6th
    Actual gear position under fail-safe mode 1st 2nd 3rd 3rd 3rd 3rd

MONITOR DESCRIPTION

The ECM commands gear shifts by turning the shift solenoid valves ON/OFF and switching oil pressure to the valves in the valve body.

The DTC indicates that the sequence valve is locked in the direction the spring stretches and that shifting to 6th gear is impossible.

INSPECTION PROCEDURE

PROCEDURE


  1. CHECK DTC OUTPUT (IN ADDITION TO DTC P0729)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the intelligent tester on.

    4. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

    5. Read the DTCs using the intelligent tester.

      Result
      Result Proceed to
      Only P0729 is output A
      P0729 and other DTCs are output B

      Tech Tips

      If any other codes besides P0729 are output, perform troubleshooting for those DTCs first.


    B
    A
  2. PERFORM ACTIVE TEST USING INTELLIGENT TESTER (RUNNING TEST)

    CAUTION:

    This test should always be performed with at least 2 people.

    Note


    • Perform the test while the ATF temperature is between 50 and 80°C (122 and 176°F).

    • Perform the test with the A/C turned off.

    Tech Tips

    Using the intelligent tester to perform Active Tests allows relays, VSVs, actuators and other items to be operated without removing any parts. This non-intrusive functional inspection can be very useful because intermittent operation may be discovered before parts or wiring is disturbed. Performing Active Tests early in troubleshooting is one way to save diagnostic time. Data List information can be displayed while performing Active Tests.


    1. Connect the intelligent tester to the DLC3.

    2. Clear the DTC Click here.

    3. Warm up the engine.

    4. Enter the following menus: Powertrain / Engine and ECT / Active Test.

    5. According to the display on the intelligent tester, perform the Active Test.

      Tech Tips

      While driving, the shift position can be forcibly changed with the intelligent tester.

      Comparing the shift position commanded by the Active Test with the actual shift position enables you to confirm the problem Click here.

      Engine and ECT
      Tester Display Test Part Control Range Diagnostic Note
      Control the Shift Position Operate shift solenoid valve and set each shift position by yourself
      • Press "→" button: Shift up

      • Press "←" button: Shift down

      Possible to check operation of shift solenoid valves.

      [Vehicle Condition]

      50 km/h (30 mph) or less

      Tech Tips


      • This test can be conducted when the vehicle speed is 50 km/h (30 mph) or less.

      • The 4th to 5th and 5th to 6th up-shift must be performed with the accelerator pedal released.

      • The 6th to 5th and 5th to 4th down-shift must be performed with the accelerator pedal released.

      • Do not operate the accelerator pedal for at least 2 seconds after shifting and do not shift successively.

      • The shift position commanded by the ECM is shown in the Data List display on the intelligent tester.

      • Gear positions in the event of a solenoid valve mechanical problem:

        Tester command gearshift 1st 2nd 3rd 4th 5th 6th
        Actual gear position under malfunction 1st 2nd 3rd 4th 5th 4th
      OK
      Gear position changes in accordance with the tester command.

    NG
    OK
  3. PERFORM ACTIVE TEST USING INTELLIGENT TESTER (SHIFT SOLENOID VALVE SLT)

    Note


    • Perform the test while the ATF temperature is between 50 and 80°C (122 and 176°F).

    • Be careful to prevent the hose of SST from interfering with the exhaust pipe.

    • Perform the test with the A/C off.

    Tech Tips

    Using the intelligent tester to perform Active Tests allows relays, VSVs, actuators and other items to be operated without removing any parts. This non-intrusive functional inspection can be very useful because intermittent operation may be discovered before parts or wiring is disturbed. Performing Active Tests early in troubleshooting is one way to save diagnostic time. Data List information can be displayed while performing Active Tests.


    1. A0156D8E01

      Remove the test plug on the transmission case and connect SST.

      SST
      09992-00095   ( 09992-00231, 09992-00271 )
    2. Connect the intelligent tester to the DLC3.

    3. Start the engine and warm it up.

    4. Measure the line pressure with SST.

    5. Turn the intelligent tester on.

    6. Enter the following menus: Powertrain / Engine and ECT / Active Test.

    7. According to the display on the intelligent tester, perform the Active Test.

    8. Measure the line pressure.

      Engine and ECT
      Tester Display Test Part Control Range Diagnostic Note
      Activate the Solenoid (SLT)* Operate the shift solenoid SLT and raise line pressure

      ON or OFF

      Tech Tips


      • OFF: Line pressure up (when Active Test "Activate the Solenoid (SLT)" is performed, ECM commands SLT solenoid to turn OFF)

      • ON: No action (normal operation)

      [Vehicle Condition]


      • Vehicle stopped

      • Engine idling

      Tech Tips

      *: Activate the Solenoid (SLT) in the Active Test is performed to check the line pressure changes by connecting SST to the automatic transmission, which is used in the Hydraulic Test Click here as well. Please note that the pressure values in the Active Test and Hydraulic Test are different.

      OK
      The line pressure changes as specified when performing the Active Test.

    NG
    OK
  4. CLEAR DTC AND PERFORM RUNNING TEST


    1. Clear the DTC Click here.

    2. Check the DTC again after conducting the Monitor Drive Pattern Click here.

      OK
      No DTC code output.

    NG
    OK