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Home >> Chevrolet >> 2001 >> Venture Base, Van Passenger >> Repair and Diagnosis >> External Pages >> Different car >> Section 35 (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 2002 Buick Regal, 2002 Buick Century, 2001 Buick Regal, and 2001 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 step  7 . If not, go to next step.
  3. Turn ignition off. Disconnect the transaxle in-line 20-way 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  5 .
  4. Test the signal circuit (CKT 1804) of the TCC release switch for a short to ground between the transaxle in-line 20-way connector and the TFP manual valve position switch. Did you find the condition? If so, go to step  9 . If not, go to step  6 .
  5. 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-way connector. Did you find and correct the condition? If so, go to step  11 . If not, go to step  10 .
  6. 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  8 . If not, go to next step.

  7. Inspect for the following conditions:
    • TCC control valve stuck in the apply position.
    • TCC feed limit valve stuck.
    • TCC regulator apply valve stuck in the apply position.
    • TCC PWM solenoid valve stuck or exhaust restricted.
    • Pressure regulator valve stuck.
    • TCC fluid circuits leaking.
    • Abnormally high or low line pressure.

    Repair or replace any malfunctioning components. Did you find and correct a condition? If so, go to step  11 . If not, see DIAGNOSTIC AIDS  .

  8. 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  11 .
  9. 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  11 .
  10. Replace the PCM. See POWERTRAIN CONTROL MODULE  under REMOVAL & INSTALLATION. Did you complete the replacement? If so, go to next step.
  11. 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.
    • Slip speed must be 150-200 RPM.
    • The TCC release switch must be open, indicating TCC release pressure is present, for 5 seconds.
    • Select SPECIFIC DTC.
    • Enter DTC P0742.

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

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