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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 968 (Automatic Transmission - 4L80-E/4L85-E, Diagnosis (P0218 To P2771)) >> Diagnosis >> DTC P0742 >> Test Description

Test Description

WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The number below refers to the step number on the diagnostic table.

  1. 3:  This step tests the mechanical state of the TCC. When the PCM commands the TCC solenoid OFF, the slip speed should increase.
DTC P0742

Step Action Value(s) Yes No
1 Did you perform the Diagnostic System Check - Engine Controls? - Go to Step 2  Go to Diagnostic System Check - Engine Controls in Engine Controls - 4.8L, 5.3L, and 6.0L
2
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
    3. IMPORTANT: Before clearing the DTCs, use the scan tool in order to record the Freeze Frame and Failure Records. Using the Clear Info function erases the Freeze Frame and Failure Records from the PCM.
  3. Record the Freeze Frame and Failure Records.
  4. Clear the DTCs.
  5. Select scan tool TP angle and TP sensor.
  6. Apply the accelerator pedal.
Are the TP sensor values within the specified range?		 0.2-0.9 V at 0% to 4.5 V at 100% Go to Step 3  Go to Diagnostic Aids
3  Drive the vehicle in D4 to achieve FOURTH gear under steady acceleration, with the throttle 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 0 percent?		 - Go to Step 4  Go to Diagnostic Aids
4
  1. Inspect the transmission for the following conditions:
    • TCC PWM solenoid valve for a damaged exhaust orifice
    • TCC shift valve for being stuck

      Refer to Torque Converter Clutch (TCC) Valve and Spring Replacement .

    • Converter regulated apply valve stuck in the released position
    • Restricted apply or release passage

      Refer to Transmission Oil Pump Disassemble in Transmission Unit Repair article.

    • Misaligned or damaged valve body gasket

      Refer to Control Valve Body Assembly Removal in Transmission Unit Repair article.

    • Torque converter mechanically stuck ON

      Refer to Torque Converter Diagnosis Procedure .

  2. Repair any of the above conditions as necessary.
Did you complete the repair?		 - Go to Step 5  -
5 Perform the following procedure in order to verify the repair:
  1. Select DTC.
  2. Select Clear Info.
  3. Operate the vehicle under the following conditions:
    • Operate the vehicle in D4 with the TCC duty cycle 0 percent and throttle above 12 percent.
    • Ensure that the TCC slip speed is greater than 100 RPM for 2 seconds.
  4. Select Specific DTC.
  5. Enter DTC P0742.

Has the test run and passed?		 - Go to Step 6  Go to Step 2 
6 With the scan tool, observe the stored information, capture info and DTC info.
Does the scan tool display any DTCs that you have not diagnosed?		 - Go to Diagnostic Trouble Code (DTC) List in Engine Controls - 4.8L, 5.3L, and 6.0L System OK
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