Circuit Description

WARNING: This page is about a different car, the 2003 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

The torque converter has an electrically controlled capacity clutch (ECCC). At certain speeds, the TCC lockup pressure control (PC) solenoid is precisely controlled to maintain a small amount of slippage between the engine and the transaxle, reducing driveline torsional disturbances. The transmission control module (TCM) uses information from the output speed sensor (OSS) to determine if shudder is present by calculation of OSS frequency variance. The TCM monitors the OSS to detect shudder while the TCC is partially applied. If too much shudder is detected with the TCC partially applied, the TCM will then release the TCC, and monitor the OSS again for shudder. This allows the TCM to determine if the shudder is caused by the TCC system or by a rough road surface. DTC P0744 sets when the OSS indicates too much TCC shudder with the TCC partially applied, and no shudder with the TCC released. DTC P0744 is a C type DTC.