Circuit Description
The torque converter clutch (TCC) solenoid valve is a normally-open exhaust valve that is used with the torque converter clutch pulse width modulation (TCC PWM) solenoid valve in order to control fluid acting on the converter clutch apply valve. The TCC solenoid valve attaches to the transmission case assembly extending into the pump cover. When grounded, energized, by the transmission control module (TCM), the TCC solenoid valve stops converter signal oil from exhausting. This causes converter signal oil pressure to increase and move the converter clutch apply valve against spring force and into the apply position. In this position, release fluid is open to an exhaust port and converter feed fluid fills the apply fluid circuit. The converter feed fluid applies the TCC. When the TCM no longer provides a ground path, the TCC solenoid valve de-energizes and apply fluid exhausts, releasing the TCC.
When the TCM detects low torque converter slip when the TCC is commanded OFF, then DTC P0742 sets. DTC P0742 is a type B 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 OSS DTCs P0722 or P0723. |
| • | No TCC performance DTC P0741. |
| • | No TCC electrical DTCs P2763, P2764. |
| • | Ignition voltage is between 8-18 volts. |
| • | The engine run time is greater than 5 seconds. |
| • | The transmission fluid temperature is 10-130°C (50-266°F). |
| • | The engine speed is 800-4,400 RPM. |
| • | The engine torque is greater than 156 N·m (115 lb ft). |
| • | The throttle position is 10 percent or greater. |
| • | The commanded gear is not 1st gear and the gear ratio is 0.95:1-1.56:1. |
| • | The vehicle speed is greater than 11 km/h (7 mph). |
| • | TCC is commanded OFF. |
Conditions for Setting the DTC
The following conditions occur 4 times in 1 ignition cycle:
The TCC slip is between -15 to +15 RPM for greater than 3 seconds.
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 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 P0742 in TCM history. |
Conditions for Clearing the DTC
| • | The ECM 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 a non-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. |
Diagnostic Aids
The TCC fluid hydraulically applies the TCC, possibly causing an engine stall, under the following conditions:
| • | The TCC is hydraulically stuck ON. |
| • | The parking brake is applied. |
| • | Any gear range is selected. |
| • | Contamination may cause the TCC apply valve to intermittently stick in the valve body. |
| • | Internal damage in the torque converter may cause no TCC apply. |
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Values | Yes | No | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |||||||||||
Important: Before clearing the DTC, use the scan tool in order to record the Freeze Frame and Failure Records. Using the Clear Info. function erases the Freeze Frame and Failure Records from the transmission control module (TCM). While the scan tool TCC Enable status is NO, does the scan tool display a TCC Slip Speed within the specified range? | -20 to +20 RPM | Go to Step 3 | Go to Diagnostic Aids | |||||||||||
3 | The torque converter clutch (TCC) is hydraulically stuck ON. Inspect for the following:
Did you find and correct the condition? | -- | Go to Step 4 | -- | ||||||||||
4 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | Go to Step 5 | Go to Step 2 | ||||||||||
5 | With the scan tool, observe the stored information, capture info, and DTC Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK |
