Theory Of Operation

The Transmission Control Module (TCM) monitors the pressure regulator and solenoid logic to detect a failure in the activation of the pressure regulators and solenoids. The pressure regulators are used to control the pressure to the clutches and the solenoids are used to activate the pressure to the parking lock and to the position valve. The commanded currents of all regulators and solenoids are monitored. The monitoring consists of several diagnostic strategies:

• Transmission blocking (Multiple clutches locked up)
• Wrong driving direction (Incorrect driving direction)
• Gear engagement of Reverse gear while driving forward (Unallowed Reverse engagement)
• Unwanted engaging or disengaging of Parking Lock (Unallowed Park engagement)