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Home >> Subaru >> 2000 >> Outback Base, Automatic >> Repair and Diagnosis (Single Page) >> Transmission >> Automatic Trans >> Diagnosis - 4-ATAXLE >> Diagnostic Tests >> DTC 75/P0748: Line Pressure Duty Solenoid >> Diagnostic Procedure (Forester & Impreza)

Diagnostic Procedure (Forester & Impreza)

  1. Turn ignition switch to OFF position. Disconnect dropping resistor Gray 4-pin connector. See Figure . Using DVOM, measure resistance between dropping resistor connector terminals No. 1 and 2. See Figure . If resistance is 9-15 ohms, go to next step. If resistance is not 9-15 ohms, replace dropping resistor.
  2. Disconnect TCM 24-pin connector B54. Using DVOM, measure resistance between TCM harness connector B54 terminal No. 18 and dropping resistor harness connector terminal No. 1. 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 dropping resistor.
  3. Using DVOM, measure resistance between dropping resistor harness connector terminal No. 1 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 dropping resistor.
  4. Disconnect transaxle 20-pin connector B11. Using DVOM, measure resistance between transaxle harness connector B11 terminal No. 5 and dropping resistor harness connector terminal No. 2. If resistance is less than one ohm, go to next step. If resistance is one ohm or more, repair open in harness between dropping resistor and transaxle connector.
  5. Using DVOM, measure resistance between dropping resistor harness connector terminal No. 2 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 dropping resistor and transaxle connector.
  6. Using DVOM, measure resistance between transaxle connector T4 terminal No. 16 and ground. If resistance is less than one ohm, go to next step. If resistance is one ohm or more, repair open circuit in transaxle harness.
  7. Using DVOM, measure resistance between transaxle connector T4 terminal No. 5 and ground. If resistance is 2.0-4.5 ohms, go to next step. If resistance is not 2.0-4.5 ohms, go to step  17 .
  8. Using DVOM, measure resistance between TCM harness connector B54 terminal No. 9 and transaxle harness connector B11 terminal No. 5. 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.
  9. Using DVOM, measure resistance between TCM harness connector B54 terminal No. 9 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.
  10. If Subaru Select Monitor is available, go to step  15 . If Subaru Select Monitor is not available, go to next step.
  11. Reconnect TCM and transaxle connectors. Start engine and warm transaxle ATF to normal operating temperature. ATF must reach 176°F (80°C). Turn ignition switch to OFF position, then turn ignition switch to ON position (engine off). Place selector lever in "N" position. Using DVOM, measure voltage by backprobing between TCM harness connector B54 terminal No. 9 and ground. If voltage is 1.5-4.0 volts with throttle fully closed, go to next step. If voltage is not 1.5-4.0 volts with throttle fully closed, go to step  19 .
  12. Using DVOM, measure voltage by backprobing between TCM harness connector B54 terminal No. 9 and ground. If voltage is less than one volt with throttle fully open, go to next step. If voltage is one volt or more with throttle fully open, go to step  19 .
  13. Using DVOM, measure voltage by backprobing between TCM harness connector B54 terminal No. 18 and ground. If voltage is more than 8.5 volts with throttle fully closed, go to next step. If voltage is 8.5 volts or less with throttle fully closed, go to step  19 .
  14. Using DVOM, measure voltage by backprobing between TCM harness connector B54 terminal No. 18 and ground. If voltage is less than one volt with throttle fully open 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 one volt or more with throttle fully open, go to step  19 .
  15. Reconnect TCM and transaxle connectors. Connect Subaru Select Monitor to DLC. Start engine and warm transaxle ATF to normal operating temperature. ATF must reach 176°F (80°C). Turn ignition switch to OFF position, then turn ignition switch to ON position (engine off). Place selector lever in "N" position. Using Subaru Select Monitor, monitor line pressure duty solenoid data. With throttle fully closed, line pressure duty value should be 100 percent. If line pressure duty value is as specified, go to next step. If line pressure duty value is not as specified, go to step  19 .
  16. Ensure ignition switch is in ON position (engine off). With throttle fully open, check line pressure duty output signal from TCM. If value is 10-20 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 value is not 10-20 percent, go to step  19 .
  17. Turn ignition switch to OFF position. Remove transaxle connector from bracket. Drain transaxle fluid when cool. Remove oil pan and disconnect connector from line pressure duty solenoid. Using DVOM, measure resistance between line pressure duty solenoid connector and ground. If resistance is 2.0-4.5 ohms, go to next step. If resistance is not 2.0-4.5 ohms, replace line pressure duty solenoid.
  18. Using DVOM, measure resistance between transaxle connector T4 terminal No. 5 and line pressure duty solenoid harness terminal. If resistance is less than one ohm, go to next step. If resistance is one ohm or more, repair open in harness between line pressure duty solenoid and transaxle connector.
  19. Check for poor contact in line pressure duty solenoid circuit. If contact is poor, repair as necessary. If contact is okay, replace TCM and retest.
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