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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 59 (Automatic Transmission Diagnosis - 4L80-E) >> Diagnostic Tests >> DTC P0742: TCC System Stuck On >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2002 GMC Yukon XL, 2002 GMC Sierra, 2002 Chevrolet Suburban, and 2002 Chevrolet 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 DTCs, use the scan tool to record the freeze frame and failure records. Using the CLEAR INFO function erases the freeze frame and failure records from the PCM. Record the freeze frame and failure records. Clear the DTCs. Select TP ANGLE and TP SENSOR on scan tool. Apply the accelerator pedal. Are the TP sensor values 0.2-0.9 volt at zero percent to 4.5 volts at 100 percent? If so, go to next step. If not, see DIAGNOSTIC AIDS .
  3. Drive the vehicle in the D4 drive range in 4th gear under steady acceleration with a TP sensor angle greater than 12 percent. Does the scan tool display a TCC slip speed of -10 to 10 RPM while the displayed TCC duty cycle is zero percent? If so, go to next step. If not, see DIAGNOSTIC AIDS .
  4. The TCC is mechanically stuck on. Perform the following inspections:
    • Inspect the exhaust orifice in the TCC PWM solenoid valve for any clogging.
    • Inspect the converter clutch apply valve for the possibility of being stuck in the apply position.
    • Inspect the valve body gasket for misalignment or damage.
    • Inspect for a restricted release or apply passage.
    • Inspect for restricted transmission cooler line.

    Did you find and correct the condition? If so, go to next step.

  5. Perform the following procedure to verify the repair:
    • Select DTC.
    • Select CLEAR INFO.
    • Operate the vehicle in D4 with the TCC duty cycle zero percent and throttle angle above 12 percent.
    • Ensure that the TCC slip speed is greater than 175 RPM for 6 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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