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stin1974, Auto Service Technician
Category: Car
Satisfied Customers: 765
Experience:  Domestic transmission diagnostics and troubleshooting. General repair diagnostics and troubleshoot.
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I got areading of PO742 which told me my torque converter celenoid

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I got areading of PO742 which told me my torque converter celenoid was stuck on... What does that mean?
What year make and model vehicle? engine?
Customer: replied 8 years ago.
Cheverolet Impala 2003 3.4
Does the vehicle seem to idle bad when put in gear or want to stall out in gear at an idle? Is the vehicle acting a certain way or did you just have it scanned because the light came on in the dash?
Customer: replied 8 years ago.
Shifts hard not all the time, if car sits for a day or two no problem just when it has to stop and go. I had a reading of the torque conveter cluctch solenoid stuck on.

This will explain everything about the code you have.


DTC P0742

Circuit Description
The TCC release switch is part of the automatic Transmission Fluid Pressure (TFP) manual valve position switch. The TFP manual valve position switch is mounted to the transmission valve body.

The TCC release switch is a normally-closed switch. When the TCC is released, TCC release fluid pressure opens the TCC release switch which opens the TCC release pressure circuit. When, the voltage on the circuit is high, switch open, the PCM recognizes that the TCC is no longer engaged.

If the PCM detects that the TCC release switch is closed when the TCC is commanded OFF, then DTC P0742 sets. DTC P0742is a type B DTC.

Conditions for Running the DTC

  • No TP sensor DTC P0121,P0122 or P0123.
  • No TCC PWM solenoid valve DTC P1860.
  • No TCC release switch DTC P1887.
  • The engine speed is greater than 500 RPM and not in fuel shut off.
  • The engine torque is 95 - 270 Nm (70 - 200 ft. lbs.).
  • The TP angle is 5 - 45 percent.
  • The transmission fluid temperature is 10 - 130°C (50 - 266°F).
  • The time since the last gear range change is greater than 6 seconds.
  • The TCC is commanded OFF.

Conditions for Setting the DTC
The TCC release switch is closed 6 times for 4 seconds each, during one trip.

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.
  • The PCM commands the TCC ON at maximum capacity.
  • The PCM freezes transmission adaptive functions.
  • The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame and Failure Records.
  • The PCM stores DTC P0742 in PCM history.

Conditions for Clearing the MIL/DTC

  • The PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
  • A scan tool can clear the MIL/DTC.
  • The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
  • The PCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the PCM.

Diagnostic Aids

  • The customer may notice an engine stalling, condition.
  • If the scan tool indicated TCC release pressure was present in Step 2 and a mechanical or hydraulic condition was not found in Step 8, an intermittent short to ground condition may exist in the TCC release switch signal circuit.
  • Do not replace the torque converter for this condition, refer to Torque Converter Replacement Guide for other concerns.
  • Residue or contamination may cause valves to stick intermittently.

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

  1. A Yes answer indicates that the TCC Release Switch is functioning properly.
  1. With the 20-way connector disconnected, the PCM should interpret the open circuit as TCC release pressure present.
  2. The TCC release switch is a normally closed switch and must be disconnected to properly test for a short to ground condition. An open condition in the TCC release circuit or switch: would set DTC P1887. Open circuits are not diagnosed in DTC P0742.
  1. This step tests for a mechanical or hydraulic condition that would cause the TCC to be stuck ON.

Steps 1 - 6

Steps 7 - 11

Steps 12 - 13

DTC P0742

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