GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 1998 🢒 Trans Sport Ext. 🢒 DTC 🢒 DTC P0742 TCC System Stuck On

Object Number: 190908 Size: MF
Automatic Transmission Components
Automatic Transmission Controls Schematics
OBD II Symbol Description Notice

Circuit Description

The PCM energizes the Torque Converter Clutch Solenoid Valve (TCC Sol. Valve) by creating a ground path on circuit 422. When grounded (energized), the TCC Sol. Valve stops converter signal oil from exhausting. This causes converter signal oil pressure to increase and move the TCC apply valve. When the TCC Sol. Valve is de-energized, the valve will exhaust fluid and release the TCC.

When the PCM detects 3 occurrences of TCC slip between -20 and +50 RPM for 5 seconds, indicating the TCC is applied when commanded OFF, then DTC P0742 sets. DTC P0742 is a type B DTC.

Conditions for Setting the DTC
    • No TP DTCs P0122 or P0123.
    • No VSS DTCs P0502 or P0503.
    • No TCC PWM solenoid electrical DTC P1860.
    • No TCC enable solenoid electrical DTC P0740.
    • Not in fuel shut off.
    • The engine speed is more than 500 RPM for 5 seconds.
    • The PCM has commanded the TCC OFF.
    • The commanded gear is not 1st.
    • The transmission gear indicates 2nd, 3rd or 4th.
    • The throttle angle is between 14-50%.
    • The engine torque is 95-271 N·m (70-200 lb ft).
    • The TCC slip speed is -20 to +50 RPM, for 3 occurrences of greater than 5 seconds.
    • The engine speed is 800-4,000 RPM.
    • The vehicle speed is 32-112 km/h (20-70 mph).
    • The speed ratio is 0.65-1.18.
    • The last gear range change occurred more than 3 seconds ago.

Action Taken When the DTC Sets

The PCM illuminates the Malfunction Indicator Lamp (MIL) during the second consecutive trip in which the conditions for setting the DTC are met.

Conditions for Clearing the MIL/DTC
    • The PCM turns OFF the MIL after three consecutive trips without a failure reported.
    • A scan tool can clear the DTC from the PCM history. The PCM clears the DTC from the PCM history if the vehicle completes 40 warm-up cycles without a failure reported.

Diagnostic Aids
    • Check for PRNDL DTC P0705. DTC P0705 affects transmission operation. This may set DTC P0742 falsely.
    • Inspect the transmission fluid for debris.

Test Description

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

  1. A TCC slip speed in the range shown indicates that this DTC is current. Refer to the Diagnostic Aids. Inspect for PRNDL DTC P0705.

DTC P0742 Torque Converter Clutch System Stuck ON

Step

Action

Value(s)

Yes

No

1

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

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Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check in Engine Controls

2

  1. Install the Scan Tool .
  2. With the engine OFF, turn the ignition switch to the RUN position.

    3. Important: Before clearing the DTCs, use the Scan Tool in order to record the Freeze Frame and Failure Records for reference. Using the Clear Info function will erase the stored Freeze Frame and Failure Records from the PCM.

  3. Record the DTC Freeze Frame and Failure Records, then clear the DTC.
  4. Start and run the vehicle.
  5. Select TCC Slip Speed on the Scan Tool .
  6. With the transmission in D4, drive the vehicle through the 1-2 upshift.

In second gear is the TCC Slip Speed within the range specified?

-20 to +50 RPM

Go to Step 3

Go to Diagnostic Aids

3

Inspect for the following conditions:

  1. The TCC Enable solenoid stuck ON because of sediment.
  2. The TCC apply valve stuck ON because of sediment or a bent or sticking valve. Refer to Transmission Overhaul in the 4T60-E Section of the Transmission Unit Repair Manual.

Was a condition found and corrected?

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Go to Step 4

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4

In order to verify your repair, perform the following procedure:

  1. Using the Scan Tool , clear DTC information.
  2. Operate the vehicle under the following conditions:
    3. • The gear range is D2, D3 or D4.
    • The commanded gear is not 1st.
    • The engine speed is greater than 500 RPM for 5 seconds.
    • Not in fuel shut off.
    • The engine torque is 95-270 N·m (70-200 lb ft).
    • The throttle position is 14-50%.
    • The PCM commands the TCC OFF.
    • The TCC slip speed is between 150-2,000 RPM for 5 seconds.
    • The engine speed is 800-4,000 RPM.
    • The vehicle speed is 32-112 km/h (20-70 mph).
    • The speed ratio is 0.65-1.18.
    • The last gear change occurred more than 3 seconds ago.
  3. Select Specific DTC. Enter DTC P0742.

Has the test run and passed?

--

System OK

Go to Step 1