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Home >> Chevrolet >> 2001 >> Camaro Base, 2D Convertible, Automatic >> Repair and Diagnosis >> Transmission >> Automatic Trans >> Automatic Transmission Diagnosis - 4L60-E >> Diagnostic Tests >> DTC P0748: Pressure Control Solenoid Circuit - Electrical Malfunction >> Diagnostic Procedure

Diagnostic Procedure

  1. Did you perform the diagnostic system check? If so, go to next step. If not, see DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM.
  2. Connect scan tool to DLC. Turn ignition on, engine off. Using scan tool, record failure records for reference, and then clear DTCs. Start engine. Using scan tool, apply 0.1-1.0 amp and observe scan tool display. If PC solenoid actual amperage reading is within 0.16 amp of desired reference amperage reading, see DIAGNOSTIC AIDS . If PC solenoid actual amperage reading is not within 0.16 amp of desired reference amperage reading, go to next step.
  3. Turn ignition off. Disconnect transmission 20-pin in-line harness connector. Install appropriate jumper harness to transmission side of 20-pin in-line harness connector. Measure resistance between terminals "C" and "D" at jumper harness. If resistance is 3-7 ohms, go to step  5. If resistance is not as specified, go to next step.
  4. If resistance is greater than 7 ohms, go to step  9. If resistance is not greater than 7 ohms, go to step  10.
  5. Measure resistance between transmission case and terminal "C" at jumper harness. If resistance is greater than 250 k/ohms, go to next step. If resistance is not greater than 250 k/ohms, go to step  11.
  6. Disconnect jumper harness. Reconnect transmission 20-pin in-line harness connector. Disconnect PCM harness connector associated with PC solenoid circuit. See WIRING DIAGRAMS . Measure resistance between PC solenoid valve controlled power and ground circuits at PCM harness connector. If resistance is 3-7 ohms, go to step  8. If resistance is not 3-7 ohms, go to next step.
  7. If resistance is greater than 7 ohms, go to step  12. If resistance is not greater than 7 ohms, go to step  13.
  8. Measure resistance between ground and PC solenoid valve controlled power circuit at PCM harness connector. If resistance is greater than 250 k/ohms, go to step  17. If resistance is not greater than 250 k/ohms, go to step  14.
  9. Check for open in PC solenoid valve controlled power and ground circuits between in-line harness connector and PC solenoid valve. If circuit(s) is open, go to step  16. If circuits are okay, go to step  15.
  10. Check PC solenoid valve controlled power and ground circuits for short together between in-line harness connector and PC solenoid valve. If circuits are shorted, go to step  16. If circuits are okay, go to step  15.
  11. Check PC solenoid valve controlled power and ground circuits for short to ground between in-line harness connector and PC solenoid valve. If circuits are shorted, go to step  16. If circuits are okay, go to step  15.
  12. Check for open in PC solenoid valve controlled power and ground circuits between in-line harness connector and PCM. Repair as necessary. After repairs, go to step  18.
  13. Check PC solenoid valve controlled power and ground circuits for short together between in-line harness connector and PCM. Repair as necessary. After repairs, go to step  18.
  14. Check PC solenoid valve controlled power and ground circuits for short to ground between in-line harness connector and PCM. Repair as necessary. After repairs, go to step  18.
  15. Replace PC solenoid valve. See appropriate AUTOMATIC article in TRANSMISSION SERVICING. After repairs, go to step  18.
  16. Replace transmission wiring harness assembly. See appropriate AUTOMATIC article in TRANSMISSION SERVICING. After repairs, go to step  18.
  17. Replace PCM. After replacement, program PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article in ENGINE PERFORMANCE. After repairs, go to next step.
  18. Using scan tool, clear DTCs. Start engine and ensure difference in actual and reference PC solenoid valve current is less than 0.16 amp. Check for DTCs. If DTC P0748 does not return, system is okay. If DTC P0748 returns, repeat step  1.
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