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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 69 (Automatic Transmission Diagnosis - 4L80-E (Diesel)) >> Diagnostic Tests >> DTC P0753: 1-2 Shift Solenoid Valve Circuit - Electrical Malfunction >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2002 GMC Cab & Chassis Sierra and 2002 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  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. Install a scan tool. Turn ignition on, engine off. Before clearing the DTC, use the scan tool to record the freeze frame and failure records for reference. The CLEAR INFO function will erase the data. Record the DTC freeze frame and failure records. Clear the DTC. Is DTC P0758 or DTC P1860 set? If so, go to next step. If not, go to step  4 .
  3. Inspect the transmission fuse for an open. Is the fuse open? If so, go to step  12 . If not, go to step  5 .
  4. Use the scan tool to command the 1-2 shift solenoid valve on and off three times while listening to the bottom of the transmission pan. A stethoscope may be necessary. Does the solenoid click when commanded? If so, see DIAGNOSTIC AIDS  . If not, go to next step.
  5. Turn ignition off. Disconnect the transmission in-line 20-way connector. Additional DTCs may set. Install the Jumper Harness (J-44152) on the engine side of the transmission in-line 20-way connector. Turn ignition on, engine off. Using the Connector Test Adapter Kit (J-35616-A), connect a test light from terminal "E" of the jumper harness to ground. Does the test light illuminate? If so, go to next step. If not, go to step  15 .
  6. Connect a test light between jumper harness terminals "E" and "A". Use the scan tool to command the 1-2 shift solenoid valve on and off three times. Does the test light turn on and off with each command? If so, go to step  8 . If not, go to next step.
  7. Is the test light always on? If so, go to step  16 . If not, go to step  17 .
  8. Install the jumper harness on the transmission side of the transmission in-line 20-way connector. Measure the resistance between jumper harness terminals "A" and "E". Does the resistance measure 19-31 ohms? If so, go to next step. If not, go to step  10 .
  9. Measure the resistance from terminal "A" to ground and terminal "E" to ground. Do both readings measure greater than 250 k/ohms? If so, see DIAGNOSTIC AIDS  . If not, go to step  11 .
  10. Disconnect the wiring harness from the 1-2 shift solenoid valve. Measure the resistance of the 1-2 shift solenoid valve. Does the resistance measure 19-31 ohms? If so, go to step  18 . If not, go to step  19 .
  11. Disconnect the wiring harness from the 1-2 shift solenoid valve. Measure the resistance from the component's terminals to ground. Do both readings measure greater than 250 k/ohms? If so, go to step  18 . If not, go to step  19 .
    12. NOTE: The condition that affects this circuit may exist in other connecting branches of the circuit.
  12. Test the 1-2 shift solenoid valve voltage circuit (1020) for a short to ground between the instrument panel fuse block and the transmission in-line 20-way connector. Did you find and correct the condition? If so, go to step  21 . If not, go to next step.
    13. NOTE: The condition that affects this circuit may exist in other connecting branches of the circuit.
  13. Test the 1-2 shift solenoid valve voltage circuit (839) for a short to ground between the transmission in-line 20-way connector and the 1-2 shift solenoid valve. Did you find a short to ground condition? If so, go to step  18 . If not, go to next step.
  14. Test each solenoid for a short to ground. Replace the faulty solenoid as necessary. Did you complete the replacement? If so, go to step  21 .
    15. NOTE: The condition that affects this circuit may exist in other connecting branches of the circuit.
  15. Test the voltage circuit (1020) of the 1-2 shift solenoid valve for an open. Did you find and correct the condition? If so, go to step  21 .
  16. Test the 1-2 shift solenoid control circuit (1222) for a short to ground between the PCM connector C3 terminal C4 and the transmission in-line 20-way connector. Did you find and correct the condition? If so, go to step  21 . If not, go to step  20 .
  17. Test the 1-2 shift solenoid circuit (1222) for an open or short to power between the PCM connector C3 terminal C4 and the transmission in-line 20-way connector. Did you find and correct the condition? If so, go to step  21 . If not, go to step  20 .
  18. Replace the transmission internal wiring harness assembly. See TRANSMISSION INTERNAL WIRING HARNESS  under REMOVAL & INSTALLATION. Did you complete the replacement? If so, go to step  21 .
  19. Replace the 1-2 shift solenoid valve. See SOLENOID VALVES  under REMOVAL & INSTALLATION. Did you complete the replacement? If so, go to step  21 .
  20. Replace the PCM. See POWERTRAIN CONTROL MODULE  under REMOVAL & INSTALLATION. Did you complete the replacement? If so, go to next step.
  21. Perform the following procedure to verify the repair:
    • Select DTC.
    • Select CLEAR INFO.
    • Place the gearshift lever in the "D4" position.
    • Drive the vehicle.
    • The PCM commands the 1-2 shift solenoid valve on and the voltage input drops to zero.
    • The PCM commands the 1-2 shift solenoid valve off and the voltage input increases to battery voltage.
    • All conditions are met for 5 seconds.
    • Select SPECIFIC DTC.
    • Enter DTC P0753.

    Has the test run and passed? If so, system is okay. If not, go to step  1 .

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