Transmission Control Module (TCM) (Aw50/51 AWD; 2005-2010): Function: Shift-Lock
To avoid any chance of the gear selector inadvertently moving from the P or N position, the car is also equipped with an electrically operated shift-lock function. This locks the interlock pin in the gear selector lever in the shift-lock section, locking the selector lever in the P- or N position.
From P to another gear position
To move the gear selector from the P position, the ignition must be switched on and the brake pedal depressed. (The stop lamp switch is activated.). The transmission control module (TCM) retrieves the brake pedal position via the CAN network and the currently selected gear from the internal gear-shift position sensor. The signal is then transmitted from the transmission control module (TCM) to the gear selector module (GSM) to control the solenoid (electro magnet) in the gear selector assembly. When the gear selector is in position P, the solenoid is activated and the lock pin slides in. The gear selector lock button can be pressed down as usual to select another gear. There is a Hall sensor in the gear selector assembly which is affected by a permanent magnet on the cover of the assembly. The Hall sensor is deactivated when the gear selector is moved from position P. The shift-lock solenoid is disengaged at the same time. This prevents the gear selector from sticking in position N. When the ignition is in position "I" or "0" the solenoid is deactivated. The gear selector is mechanically locked in position P by breaking the power supply to the solenoid.
From N to another gear position
To move the gear selector from the N position, the ignition must be switched on and the brake pedal depressed. (The stop lamp switch is activated.). The transmission control module (TCM) retrieves the brake pedal position via the CAN network and the currently selected gear from the internal gear-shift position sensor. The signal is then transmitted from the transmission control module (TCM) to the gear selector module (GSM) to control the solenoid (electro magnet) in the gear selector assembly.
With the gear selector in N the solenoid deactivates and the lock pin is drawn in and the gear selector can be shifted to position D and M normally. However the lock button on the gear selector must be pressed before R or P can be selected. When the ignition is in position "I" or "0", the solenoid is deactivated.
Shift-lock override
The mechanical lock mechanism in the gear selector assembly can be overridden so that the gear selector can be moved when the power is off or in the event of an electrical fault. A small tool can be inserted under a cover on the gear selector assembly panel to release the gear selector.