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Home >> Pontiac >> 2004 >> Sunfire Automatic >> Repair and Diagnosis >> External Pages >> Different car >> Section 91 (Automatic Transaxle - 4T40-E/4T45-E Diagnosis (DTC P0218 To P0748 - 2.2L)) >> Diagnostic Information and Procedures >> DTC P0742 (3.4L) >> Test Description

Test Description

WARNING: This page is about a different car, the 2004 Pontiac Grand Am and 2004 Oldsmobile Alero. However, it is still accessible from the selected car via links, so may be relevant.

The numbers below refer to the step numbers on the diagnostic table.

  1. 2:  This step tests for a TCC release switch status change when the engine is running. If TCC release oil is present, the switch should be open.
  2. 3:  If you disconnect the AT inline 20-way connector, the PCM should recognize an open TCC release switch. This indicates the wiring from the AT inline 20-way connector to the PCM is good.
  3. 6:  This step ensures that the TCC release switch is in good working condition.
  4. 7:  This step tests the TCC circuit for a mechanical or hydraulic condition.
DTC P0742 (3.4L)

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 -3.4L
2 
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
    3. IMPORTANT: Before clearing the DTC, 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 DTC Freeze Frame and Failure Records.
  4. Clear the DTC.
  5. Select TCC Release Pressure on the scan tool.
  6. Start the engine.
Does the scan tool indicate TCC release pressure is present?		 - Go to Step 7  Go to Step 3 
3 
  1. Turn OFF the ignition.
  2. Disconnect the AT inline 20-way connector. Additional DTCs may set.
  3. Turn ON the ignition, with the engine OFF.
Does the scan tool indicate TCC release pressure is present?		 - Go to Step 5  Go to Step 4 
4 Test the signal circuit of the TCC release switch for a short to ground between the PCM connector C2 and the AT inline 20-way connector.
Refer to Testing for Short to Ground and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 11  Go to Step 10 
5 Test the signal circuit of the TCC release switch for a short to ground between the AT inline 20-way connector and the TFP manual valve position switch.
Refer to Testing for Short to Ground in Wiring Systems.
Did you find the condition?		 - Go to Step 9  Go to Step 6 
6 
  1. Remove the TFP manual valve position switch.
  2. Inspect the TCC release switch for the following conditions:
    • A damaged or leaking seal
    • Sediment or debris in the switch
    • Damaged switch contacts
    • Stuck switch contacts
Did you find a condition?		 - Go to Step 8  Go to Step 7 
7 
  1. Inspect for the following conditions:
    • The TCC PWM solenoid valve for the fluid exhaust being restricted
    • The TCC regulated apply valve for being stuck in the TCC apply position
    • The TCC control valve for being stuck in the TCC apply position
    • The TCC feed limit valve for being stuck

      This causes the TCC feed limit pressure, and the TCC release pressure to be low or nonexistent.

    • The pressure regulator valve for being stuck
    • The TCC fluid circuits for leaks

      Refer to Control Valve Body Disassemble in Unit Repair.

    • Abnormally high or low line pressure

      Refer to Line Pressure Check Procedure .

  2. Repair any of the above conditions as necessary.
Did you find and correct a condition?		 - Go to Step 11  Go to Diagnostic Aids
8 Replace the TFP manual valve position switch.
Refer to Transmission Fluid Pressure (TFP) Manual Valve Position Switch Replacement .
Did you complete the replacement?		 - Go to Step 11  -
9 Replace the automatic transmission wiring harness.
Refer to Wiring Harness Replacement .
Did you complete the replacement?		 - Go to Step 11  -
10 Replace the PCM.
Refer to Powertrain Control Module (PCM) Replacement in Engine Controls - 3.4L.
Did you complete the replacement?		 - Go to Step 11  -
11 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:
    • Start the engine.
    • TCC release pressure must be present for 3 seconds.
  4. Select Specific DTC.
  5. Enter DTC P0742.

Has the test run and passed?		 - Go to Step 12  Go to Step 2 
12 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 - 3.4L System OK
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