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Home >> Saturn >> 2000 >> LS1 Automatic >> Repair and Diagnosis (Single Page) >> Transmission >> Automatic Trans >> Automatic Transaxle Diagnosis - 4T40-E & 4T45-E >> Diagnostic Tests >> DTC P0748: Pressure Control Solenoid Electrical Malfunction >> Diagnostic Procedure

Diagnostic Procedure

NOTE: For connector end views and component locations, see Figure -Figure . For circuit locations, see WIRING DIAGRAMS  .
  1. Perform OBD system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  under DIAGNOSIS & TESTING. After performing OBD system check, go to next step.
  2. Connect scan tool to DLC. Turn ignition switch to ON position. Using scan tool, record freeze frame and failure records for reference. Clear DTC. Start engine. Using scan tool, apply .1-1.0 amp and observe scan tool display. If PCS actual amperage reading is not within .16 amp of desired reference amperage reading, go to next step. If PCS actual amperage reading is within .16 amp of desired reference amperage reading, see DIAGNOSTIC AIDS  .
  3. Turn ignition off. Disconnect transaxle 20-pin connector. Install Jumper Harness (J-39775) to transaxle side of 20-pin connector. Using DVOM, measure resistance between terminals "C" and "D" at jumper harness. If resistance is 3-7 ohms, go to step  7 . If resistance is not 3-7 ohms, go to next step.
  4. If resistance between terminals "C" and "D" is more than 7 ohms, go to next step. If resistance between terminals "C" and "D" is less than 7 ohms, go to step  6 .
  5. Check for open in PCS power feed and ground circuits between transaxle 20-pin connector and PCS. If open is found in PCS power or ground circuits, go to step  17 . If PCS power feed and ground circuits are okay, go to step  18 .
  6. Check for shorted together PCS power feed and ground circuits between transaxle 20-pin connector and PCS. If short is found in PCS power feed and ground circuits, go to step  17 . If PCS power feed and ground circuits are okay, go to step  18 .
  7. Measure resistance between ground and terminal "D" at jumper harness. If resistance is more than 1000 ohms, go to step  9 . If resistance is 1000 ohms or less, go to next step.
  8. Check for short to ground in PCS power feed and ground circuits between transaxle 20-pin connector and PCS. If short to ground is found in PCS power or ground circuits, go to step  17 . If PCS power feed and ground circuits are okay, go to step  18 .
  9. Disconnect jumper harness from transaxle 20-pin connector and install harness on PCM side of transaxle 20-pin connector. Disconnect PCM 80-pin connector C2. Measure resistance between ground and terminal "D" at jumper harness. If resistance is less than 10 ohms, go to next step. If resistance is 10 ohms or more, go to step  11 .
  10. Check for short to ground in PCS ground circuit between appropriate PCM connector and transaxle 20-pin connector. Repair as necessary. After repairs, go to step  20 .
  11. Measure resistance of PCS ground circuit between appropriate PCM connector and transaxle 20-pin connector. If resistance is less than 10 ohms, go to step  13 . If resistance is 10 ohms or more, go to next step.
  12. Check for open in PCS ground circuit between appropriate PCM connector and transaxle 20-pin connector. Repair as necessary. After repairs, go to step  20 .
  13. Measure resistance of PCS power feed circuit between ground and transaxle 20-pin connector. If resistance is less than 10 ohms, go to next step. If resistance is 10 ohms or more, go to step  15 .
  14. Check for short to ground in PCS power feed circuit between appropriate PCM connector and transaxle 20-pin connector. Repair as necessary. After repairs, go to step  20 .
  15. Measure resistance of PCS power feed circuit between appropriate PCM connector and transaxle 20-pin connector. If resistance is less than 10 ohms, go to step  19 . If resistance is 10 ohms or more, go to next step.
  16. Check for open in PCS power feed circuit between appropriate PCM connector and transaxle 20-pin connector. Repair as necessary. After repairs, go to step  20 .
  17. Replace internal transaxle wire harness. See HYDRA-MATIC 4T40-E & 4T45-E OVERHAUL article. After repairs, go to step  20 .
  18. Replace PCS. See HYDRA-MATIC 4T40-E & 4T45-E OVERHAUL article. After repairs, go to step  20 .
  19. Replace PCM. After replacement, program PCM. See COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION. After repairs, go to next step.
  20. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Select SPECIFIC DTC and enter DTC "P0748". Turn ignition switch to ON position. PCS actual return amperage must be .16 amp of commanded amperage. If DTC P0748 is not present, repair is complete. If DTC P0748 is still present, repeat test.
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