ELECTRONIC CONTROLLED AUTOMATIC TRANSMISSION SYSTEM, Diagnostic DTC:P0741

DTC Code DTC Name
P0741 Torque Converter Clutch Solenoid Performance (Shift Solenoid Valve SL)

SYSTEM DESCRIPTION

The ECM uses the signals from the Throttle position sensor, Air-flow meter and crankshaft position sensor to monitor the engagement condition of the lock-up clutch.

Then the ECM compares the engagement condition of the lock-up clutch with the lock-up schedule in the ECM memory to detect mechanical trouble of the shift solenoid valve SL, valve body and torque converter clutch.

B007SV2E01
DTC No. DTC Detection Condition Trouble Area
P0741 Lock-up does not occur when driving in the lock-up range (normal driving at 80 km/h [50 mph]), or lock-up remains ON in the lock-up OFF range (2-trip detection logic)

  • Shift solenoid valve SL is stuck open or closed

  • Valve body is blocked

  • Torque converter clutch

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

  • Line pressure is too low

MONITOR DESCRIPTION

Torque converter lock-up is controlled by the ECM based on O/D direct clutch (input) speed sensor NC0, output speed sensor SP2, throttle position, engine temperature, transmission temperature, and gear selection. The ECM determines the lock-up status of the torque converter by comparing the engine rpm (NE) to the input shaft rpm (NC0) or output shaft rpm (SP2). The ECM calculates the actual transmission gear by comparing input shaft rpm (NC0) to output shaft rpm (SP2). When conditions are appropriate, the ECM requests "lock-up" by applying control voltage to shift solenoid SL. When the SL is turned on, solenoid SL applies pressure to the lock-up relay valve and locks the torque converter clutch.

If the ECM detects no lock-up after lock-up has been requested or if it detects lock-up when it is not requested, the ECM interprets this as a fault in the shift solenoid valve SL or lock-up system performance.

The ECM will turn on the MIL and store the DTC.

Example:

When any of the following is met, the system judges it as a malfunction.


  1. There is a difference in rotation between before and after torque converters even when the ECM commands lock-up.

    (Engine speed is at least 75 rpm greater than input turbine speed.)

  2. There is no difference in rotation between before and after torque converters even when the ECM commands lock-up off.

    (The difference between engine speed and input turbine speed is less than 35 rpm.)

INSPECTION PROCEDURE

PROCEDURE


  1. CHECK OTHER DTCS OUTPUT (IN ADDITION TO DTC P0741)


    1. Connect the Intelligent Tester to the DLC3.

    2. Turn the ignition switch to the ON position.

    3. Turn on the tester.

    4. Select the item "Power train / Engine and ECT / DTC / Current or Pending".

    5. Read the DTCs using the Intelligent Tester.

      Result
      Display (DTC output) Proceed to
      Only "P0741" is output A
      "P0741" and other DTCs B

      Tech Tips

      If any other codes besides "P0741" are output, perform troubleshooting for those DTCs first.


    B

    GO TO DTC CHART

    A

  2. INSPECT SHIFT SOLENOID VALVE SL


    1. B007UM2E01

      Remove the shift solenoid valve SL.

    2. Measure the resistance according to the value(s) in the table below.

      Resistance
      Tester Connection

      Specified Condition

      20°C (68°F)
      Solenoid Connector (SR) - Solenoid Body (SR) 11 to 15 Ω

    3. Connect the positive (+) lead to the terminal of the solenoid connector, and the negative (-) lead to the solenoid body.

      OK
      The solenoid makes an operating sound.

    NG

    REPLACE SHIFT SOLENOID VALVE SL

    OK

  3. INSPECT TRANSMISSION VALVE BODY ASSEMBLY

    OK
    There are no foreign objects on each valve.

    NG

    REPAIR OR REPLACE TRANSMISSION VALVE BODY ASSEMBLY

    OK

  4. INSPECT TORQUE CONVERTER CLUTCH ASSEMBLY

    OK
    The torque converter clutch operates normally.

    OK

    REPAIR OR REPLACE AUTOMATIC TRANSMISSION ASSEMBLY

    NG

    REPLACE TORQUE CONVERTER CLUTCH ASSEMBLY