Theory Of Operation

The purpose of this diagnostic is to detect if one of the two Parking Lock Valves or the Position Valve in the Valve Body is stuck. The first valve is actuated by the Clutch A pressure regulator and the second valve is actuated by the Clutch C pressure regulator. The two Parking Lock Valves control the oil supply in the Valve Body to the Parking Lock. The Parking Lock can only be disengaged if both Parking Lock Valves are supplying hydraulic pressure. The solenoid controlled Position Valve controls the oil supply in the Valve Body to the clutches and to the Parking Lock.

This monitor is a once-per-trip diagnostic that only occurs after an engine start (not during remote start).

• The Parking Lock is engaged during engine off and the Parking Lock Valves are stuck in the supply position, a restart of the engine will cause an unwanted disengaging of the Parking Lock if a separate failure occurs with the second parking lock valve.
• The Parking Lock is engaged during engine off and the Position Valve is stuck in the wrong position, a restart of the engine will cause an unwanted disengaging of the Parking Lock.