P0742

DTC P0742





Circuit Description
The transmission control module (TCM) controls the torque converter clutch (TCC) lock up pressure control solenoid valve. The solenoid directs the hydraulic fluid for TCC apply and release. When the TCC is released, the engine is coupled by fluid to the transmission and TCC slip speeds of -300 RPM to +1,500 RPM, during heavy acceleration, are normal.

If the TCM detects low torque converter slip when the TCC is commanded OFF, then DTC P0742 sets. DTC P0742 is a type A DTC.

DTC Descriptor
This diagnostic procedure supports the following DTC:

DTC P0742 Torque Converter Clutch (TCC) System - Stuck On

Conditions for Running the DTC
^ No TR switch DTC P0705.
^ No TFT DTCs P0711, P0712 or P0713.
^ No ISS DTC P0717.
^ No OSS DTC P0722.
^ No engine speed DTC P0727
^ No solenoid DTCs P0962, P0963, P0966, P0967, P0970, P0971, P0973, P0974, P0976, P0977, P0979, P0980, P0982, P0983, P0985 or P0986.
^ No engine torque DTC P1781.
^ No throttle position DTC P1791.
^ No CAN DTCs U2104 or U0100.
^ The ignition voltage is 10.5 volts or greater.
^ The ignition is ON for 3.0 minutes or greater.
^ The selected gear range is Drive, Intermediate, or Low for 8 seconds.
^ The transmission fluid temperature is 20°C (68°F) or greater.
^ Not in Trans. Protection Mode.
^ The engine speed is 400 RPM or greater.
^ The engine torque is 46 - 240 Nm (25 - 177 ft. lbs.).
^ The transmission is not in 1st or 2nd gear and the gear ratio is 0.73:1 to 2.27:1.
^ The Transmission ISS is not greater than 3000 RPM.

Conditions for Setting the DTC
^ The TCM commands the TCC OFF.
^ The TCC slip is between -50 to +50 RPM for 12 seconds or greater.

Action Taken When the DTC Sets
^ The TCM requests the powertrain control module (PCM) to illuminate the malfunction indicator lamp (MIL).
^ The TCM turns the Trans. Protection Mode ON.
^ The transmission will operate in 5th gear when the transmission is shifted into D or I range and 2nd gear when shifted into L range.
^ The line pressure is at maximum.
^ The torque converter clutch (TCC) is disabled.
^ The TCM freezes the transmission adaptive functions.
^ The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as a Failure Record.
^ The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as a Freeze Frame and Failure Records.
^ The TCM stores DTC P0742 in TCM history.

Conditions for Clearing the MIL/DTC
^ The PCM turns off the MIL after the third consecutive drive trip in which the TCM does not send a MIL illumination request.
^ A scan tool can clear the DTC.
^ The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
^ The TCM cancels the DTC default actions when the ignition is OFF long enough in order to power down the TCM.

Diagnostic Aids
^ Rapid fluctuation in line pressure may set DTC P0742.
^ The customer may notice an engine stalling condition.

Test Description

Step 1 - Step 7:

Step 8 - Step 14:

Step 15 - Step 16:

The numbers below refer to the step numbers on the diagnostic table.
5. This step determines if the ISS signal is skewed by a large factor.