Circuit Description
The transmission control module (TCM) provides voltage to the torque converter clutch pulse width modulated (TCC PWM) solenoid valve through the High Side Drive 2 (HSD2). The TCM controls the on and off time of the solenoid by providing a ground through the Output Drive Module (ODM). The TCM uses a PWM duty cycle 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, which is a type 'B' DTC.
Conditions for Running the DTC
| • | The ignition voltage is between 8-18 volts. |
| • | The engine is running between 450-6,800 RPM for at least 5 seconds. |
| • | The HSD2 is commanded on. |
Conditions for Setting the DTC
DTC 2764 will set when either of the following conditions occur:
| • | The TCM detects a short to ground in the TCC PWM solenoid valve circuit when the PWM duty cycle is 20% or more, or the TCC duty cycle is 50% or less. |
| • | The TCM detects an open circuit in the TCC PWM solenoid valve circuit when the PWM duty cycle is 20% or more. |
Action Taken When the DTC Sets
| • | The TCM request the powertrain interface module (PIM) to illuminate the Check Powertrain 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. When the solenoids are off: |
| - | The transmission will operate in fifth gear without TCC, if the vehicle has successfully completed a 1-2 upshift in the current ignition cycle. If the vehicle has not completed a 1-2 shift in the current ignition cycle, the transmission will operate in fourth gear. If the transmission is operating in fifth gear, fourth gear may be obtained in the engine is stopped briefly and started again. |
| - | The line pressure is at maximum. |
| • | The TCM freezes the transmission adaptive learning function. |
| • | Torque management is inhibited. |
| • | At the time of the first failure, the TCM records the operating conditions when the 'Conditions for Setting the DTC' have been 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' have been met. The ECM stores this information as a freeze frame. |
| • | The TCM stores DTC P2764 into TCM history. |
Conditions for Clearing the MIL/DTC
| • | The PIM turns off the Check Powertrain MIL after the sixth consecutive drive trip in which the TCM does not send a Check Powertrain MIL illumination request. |
| • | Tech 2 can clear the DTC. |
| • | The TCM clears the DTC from its memory (history DTC) if the vehicle completes 40 warm-up cycles without a non-emission related DTC occurring. |
| • | The TCM cancels the DTC default actions when the ignition is off long enough to power down the TCM. |
Step | Action | Values | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
Schematic Reference: Automatic Transmission Controls Schematics For information on testing wiring faults, refer to Wiring Systems. | ||||||||
1 | Has the Diagnostic System Check - Automatic Transmission been completed? | -- | Go to Step 2 | |||||
2 |
Does the solenoid operate? | -- | Go to Step 10 | Go to Step 3 | ||||
3 |
Does the test light illuminate? | -- | Go to Step 4 | Go to Step 8 | ||||
4 |
Is the resistance reading within the specified value? | 10.0-13.63 Ω | Go to Step 5 | Go to Step 9 | ||||
5 | Using a digital ohmmeter, measure the resistance between transmission 20-way connector X121-X1, terminal X1-17 and ground. Does the check indicate a short to voltage in the wiring? | More than 50 kΩ | Go to Step 6 | Go to Step 9 | ||||
6 |
Did you find an open circuit condition? | -- | Repair open in circuit 418 | Go to Step 10 | ||||
7 | Using a digital ohmmeter, check the TCC PWM solenoid valve control circuit 418 between the transmission wiring harness TCM connector A112-T68, terminal X1-4 and the transmission wiring harness connector X121-X1, terminal X1-20 for a short to ground condition. Did you find a short to ground condition? | -- | Repair short to voltage condition in circuit 418 | Go to Step 10 | ||||
8 |
Did you find an open circuit condition? | -- | Repair open in circuit 1525 | Go to Step 10 | ||||
9 |
Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 12 | ||||
10 | Replace the TCM. Refer to Transmission Control Module Replacement for replacement procedures. Is the replacement complete? | -- | Go to Step 13 | |||||
11 | Remove and replace transmission internal wiring harness. Refer to Transmission Internal Electrical Harness Replacement. Is the replacement complete? | -- | Go to Step 13 | |||||
12 | Remove the replace the TCC PWM solenoid valve. Refer to Torque Converter Clutch Solenoid Replacement. Is the replacement complete? | -- | Go to Step 13 | |||||
13 |
Has the test run and passed? | -- | System OK | Go to Step 2 | ||||
When all diagnosis and repairs are completed, clear all DTCs and verify correct operation. | ||||||||
