Theory Of Operation

The purpose of the monitoring is to detect a stuck position of the solenoid controlled position valve in the Transmission Control Module Assembly (TCMA) hydraulic control unit. The purpose of the solenoid controlled position valve is to cut or provide oil supply in the hydraulic control unit to the clutches and to the park hold solenoid. When the engine is off and the park lock is engaged, the position valve is stuck in the wrong position. An engine restart will cause an unwanted disengaging of the park lock. This monitor is a once-per-trip diagnostic that only occurs after an engine start.