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Home >> Subaru >> 2000 >> Outback Base, Automatic >> Repair and Diagnosis (Single Page) >> Transmission >> Automatic Trans >> Diagnosis - 4-ATAXLE >> Diagnostic Tests >> DTC 77/P0743: Lock-Up Duty Solenoid >> Diagnostic Procedure (Forester & Impreza)

Diagnostic Procedure (Forester & Impreza)

  1. Check for any other DTCs. Service all other DTCs prior to servicing DTC 77 or P0743. If no other DTCs are present, go to next step.
  2. Turn ignition switch to OFF position. Disconnect transaxle 20-pin connector T4. Using DVOM, measure resistance between transaxle connector T4 terminal No. 16 and ground. See Figure . If resistance is less than one ohm, go to next step. If resistance is one ohm or more, repair open in harness between transaxle connector and lock-up duty solenoid ground.
  3. Using DVOM, measure resistance between transaxle connector T4 terminals No. 13 and ground. If resistance is less than one ohm, go to next step. If resistance is one ohm or more, go to step  12 .
  4. Disconnect TCM 24-pin connector B54. Using DVOM, measure resistance between TCM harness connector B54 terminal No. 16 and transaxle harness connector B11 terminal No. 13. See Figure and Figure . If resistance is less than one ohm, go to next step. If resistance is one ohm or more, repair open in harness between TCM and transaxle connector.
  5. Using DVOM, measure resistance between TCM harness connector B54 terminal No. 16 and ground. If resistance is more than one megohm, go to next step. If resistance is one megohm or less, repair short to ground in harness between TCM and transaxle connector.
  6. If Subaru Select Monitor is available, go to step  9 . If Subaru Select Monitor is not available, go to next step.
    7. NOTE: All wheels must be off ground to perform following test. Speed difference between front and rear wheels during the following procedure may cause ABS indicator to illuminate, but this does not indicate a malfunction. When A/T diagnosis is complete, perform ABS memory clearance procedure.
  7. Reconnect TCM and transaxle connectors. Start engine and warm transaxle ATF to normal operating temperature. ATF must reach 176°F (80°C). Raise vehicle on hoist and support with safety stands. Place selector lever in "D" position. Slowly increase vehicle speed to 47 MPH. Wheels will lock-up. Using DVOM, measure voltage by backprobing between TCM harness connector B54 terminal No. 16 and ground. If voltage is more than 8.5 volts, go to next step. If voltage is 8.5 volts or less, go to step  13 .
  8. Allow engine to idle. Place selector lever in "N" position. Using DVOM, measure voltage between TCM harness connector B54 terminal No. 16 and ground. If voltage is less than .5 volt and AT OIL TEMP indicator illuminates, concern is intermittent and circuit has returned to normal condition. A temporary poor contact in connector or harness may be cause. Repair TCM harness or connector. If voltage is .5 volt or more, go to step  13 .
    9. NOTE: All wheels must be off ground to perform following test. Speed difference between front and rear wheels during the following procedure may cause ABS indicator to illuminate, but this does not indicate a malfunction. When A/T diagnosis is complete, perform ABS memory clearance procedure.
  9. Reconnect TCM and transaxle connectors. Raise vehicle on hoist and support with safety stands. Connect Subaru Select Monitor to DLC. Start engine and warm transaxle ATF to normal operating temperature. ATF must reach 176°F (80°C). Turn Subaru Select Monitor on. Using Subaru Select Monitor, monitor lock-up duty solenoid data. Place selector lever in "D" position. Slowly increase vehicle speed to 47 MPH. Wheels will lock-up. If lock-up duty solenoid value is 95 percent, go to next step. If lock-up duty solenoid value is not 95 percent, go to step  13 .
    10. NOTE: Speed difference between front and rear wheels during the following procedure may cause ABS indicator to illuminate, but this does not indicate a malfunction. When A/T diagnosis is complete, perform ABS memory clearance procedure.
  10. Allow engine to idle. Place selector lever in "N" position. If lock-up duty solenoid value changes to 5 percent and AT OIL TEMP indicator illuminates, concern is intermittent and circuit has returned to normal condition. A temporary poor contact in connector or harness may be cause. Repair TCM harness or connector. If lock-up duty solenoid value does not change to 5 percent, go to step  13 .
  11. Remove transaxle connector from bracket. Drain transaxle fluid when cool. Remove oil pan and disconnect harness connector from lock-up duty solenoid. Using DVOM, measure resistance between lock-up duty solenoid harness connector terminal and ground. If resistance is 10-17 ohms, go to next step. If resistance is not 10-17 ohms, replace lock-up duty solenoid.
  12. Using DVOM, measure resistance between transaxle connector T4 terminal No. 13 and lock-up duty solenoid harness connector. If resistance is less than one ohm, go to next step. If resistance is one ohm or more, repair open in transaxle internal harness between transaxle connector T4 and lock-up duty solenoid.
  13. Check for poor contact in lock-up duty solenoid circuit. If contact is poor, repair as necessary. If contact is okay, replace TCM and retest.
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