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Home >> Chevrolet >> 2001 >> Venture Base, Van Passenger >> Repair and Diagnosis >> External Pages >> Different car >> Section 138 (Automatic Transaxle Diagnosis - 4T65-E) >> Diagnostic Tests >> DTC P0742: TCC System Stuck On >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2003 Buick Regal and 2003 Buick Century. 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 DTCs, 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 DTCs. Start the engine. With a scan tool, observe the TCC release pressure status. Does the scan tool indicate YES for TCC release pressure? If so, go to next step. If not, go to step  5 .
  3. Drive the vehicle above 45 mph in D3 or D4, with a TP angle of 5-45%. With the scan tool, command the TCC PWM solenoid valve ON and observe TCC Release Pressure. With the scan tool, command the TCC PWM solenoid valve OFF and observe TCC Release Pressure. While the TCC was commanded OFF did the TCC release pressure indicate NO at any time? If so, go to step  8 . If not, see DIAGNOSTIC AIDS  .
  4. Turn ignition OFF. Disconnect the transaxle in-line 20-pin connector (additional DTCs may set). Turn ignition ON, engine OFF. Observe the TCC release pressure parameter. Does the scan tool indicate YES for TCC release pressure status? If so, go to next step. If not, go to step  6 .
  5. Disconnect the transmission internal wiring harness from the TFP manual valve position switch. Test the signal circuit (CKT 1804) of the TCC release switch for a short to ground between the transaxle in-line 20-pin connector and the TFP manual valve position switch. Did you find the condition? If so, go to step  10 . If not, go to step  7 .
  6. Test the signal circuit (CKT 657) of the TCC release switch for a short to ground between the PCM connector C2 and the transaxle in-line 20-pin connector. Did you find and correct the condition? If so, go to step  12 . If not, go to step  11 .
  7. Remove the TFP manual valve position switch. Inspect the TCC release switch for the following conditions:
    • A damaged or leaking seal.
    • Sediment or debris.
    • Damaged switch contacts.
    • Stuck switch contacts.

    Did you find a condition? If so, go to step  9 . If not, go to next step.

  8. Inspect for the following conditions:
    • TCC control valve stuck in the apply position.
    • TCC PWM solenoid valve stuck or exhaust restricted or faulty internal "O" ring.
    • TCC fluid circuits leaking. See appropriate REMOVAL & INSTALLATION article.
    • The TCC blowoff valve or spring for damage or not seating. See appropriate REMOVAL & INSTALLATION article.
    • Turbine shaft seals for leaks. See appropriate REMOVAL & INSTALLATION article.
    • Pump shaft seal for leaks. See appropriate REMOVAL & INSTALLATION article.
    • Spacer plate gaskets torn/leaking. See appropriate REMOVAL & INSTALLATION article.
    • Pressure regulator valve stuck. See appropriate REMOVAL & INSTALLATION article.
    • Abnormally high or low line pressure.

    Repair or replace any malfunctioning components. Did you find and correct a condition? If so, go to step  12 . If not, see DIAGNOSTIC AIDS  .

  9. Replace the TFP manual valve position switch. See TRANSMISSION FLUID PRESSURE MANUAL VALVE POSITION SWITCH  under REMOVAL & INSTALLATION. Did you complete the replacement? If so, go to step  12 .
  10. Replace the transaxle internal wiring harness assembly. See TRANSAXLE INTERNAL WIRING HARNESS  under REMOVAL & INSTALLATION. Did you complete the replacement? If so, go to step  12 .
  11. Replace the PCM. See POWERTRAIN CONTROL MODULE  under REMOVAL & INSTALLATION. Did you complete the replacement? If so, go to next step.
  12. In order to verify your repair, perform the following procedure:
    • Select DTC.
    • Select Clear Info.
    • Drive the vehicle in a Drive range.
    • The throttle position must be 5-45 percent.
    • The time since the last range change must be greater than 6 seconds.
    • The TCC must be commanded OFF.
    • The TCC release switch must be open, indicating TCC release pressure is present, for 2 seconds.
    • Select SPECIFIC DTC.
    • Enter DTC P0742.

    Has the test run and passed? If so, go to next step. If not, go to step  2 .

  13. With a scan tool, observe the stored information, capture info and DTC info. Does the scan tool display any DTCs that you have not diagnosed? If so, go to appropriate ENGINE PERFORMANCE article. If not, the system is OK.
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