5L40-E / 5L50-E Automatic Transmission
DTC P2764
Circuit Description
The transmission control module (TCM) provides voltage to the torque converter clutch pulse width modulated (TCC PWM) solenoid valve through high side driver 2 (HSD2). The TCM controls the ON and OFF time of the solenoid by providing a ground through the output driver module (ODM). The TCM uses a PWM duty cycle, in order to control application and release of the TCC. When the solenoid is commanded OFF, the TCM senses high voltage. When the solenoid is commanded ON, the TCM senses low voltage.
When the TCM detects a continuous open or short to ground in the TCC PWM Solenoid valve circuit, then DTC P2764 sets. DTC P2764 is a type B DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P2764 Torque Converter Clutch (TCC) Pressure Control (PC) Solenoid Control Circuit Low Voltage
Conditions for Running the DTC
^ The engine run time is greater than 5 seconds.
^ HSD2 is commanded ON.
Conditions for Setting the DTC
DTC P2764 sets when either of the following conditions occur for 4.3 seconds:
^ The TCM detects an open in the TCC PWM solenoid valve circuit when the PWM duty cycle is greater than 20 percent.
^ The TCM detects a short to ground in the TCC PWM solenoid valve circuit when the PWM duty cycle is greater than 20 percent but less than 50 percent.
Action Taken When the DTC Sets
^ The TCM requests the ECM to illuminate the malfunction indicator lamp (MIL) during the second consecutive drive trip in which the Conditions for Setting the DTC are met.
^ The TCM turns off power to all solenoids.
^ The transmission will operate in fifth gear if the vehicle has successfully completed a 1-2 upshift in the current ignition cycle. If the vehicle has not completed a 1-2 upshift in the current ignition cycle, the transmission will operate in fourth gear.
^ The TCM commands maximum line pressure.
^ The TCM freezes transmission adaptive functions.
^ At the time of the first failure, the TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as a Failure Record.
^ At the time of the second failure, the ECM records the operating conditions when the Conditions for Setting the DTC are met. The ECM stores this information as a Freeze Frame.
^ The TCM stores DTC P2764 in TCM history.
Conditions for Clearing the MIL/DTC
^ The ECM turns OFF the MIL after the sixth consecutive drive trip in which the TCM does not send a MIL illumination request.
^ A scan tool can clear the MIL/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 default actions when the ignition is OFF long enough in order to power down the TCM.
Test Description
The number below refers to the step number on the diagnostic table.
2. Listen for a soft rattling sound when the solenoid energizes. Use a stethoscope if necessary.
