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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 P0742: TCC System - Stuck On >> 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. Using the CLEAR INFO function erases the freeze frame and failure records from the PCM. Record the DTC freeze frame and failure records. Clear the DTC. Use the scan tool to verify the accelerator pedal position sensor operation. Are the accelerator pedal position angle values zero percent at closed throttle and 100 percent at wide open throttle? If so, go to next step. If not, see DIAGNOSTIC AIDS  .
  3. Drive the vehicle in the "D4" range in 4th gear under steady acceleration with a accelerator pedal position angle greater than 15 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 shift 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 a 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 off and accelerator pedal position angle above 15 percent.
    • Ensure that the TCC slip speed is 175-1500 RPM for 3 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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