Lock Units Side Doors

Fig 1: Identifying Lock Units

Courtesy of VOLVO CARS CORPORATION

Lock units (6/36, 6/55-57) are installed in doors and tailgate (3/78) (6/8 on XC70 (08-)). Lock units in doors are directly connected to door modules in each door.

The lock unit in the tailgate is directly connected to the Central electronic module (CEM) and Power Operated Tailgate Module (POT) (option).

There are different versions of the lock units, depending on the configuration of the lock motors.

There are two versions of the lock units in the front doors with lock motors for:

central locking
central locking and deadlocking (market dependent).

There are four versions of the lock units in the rear doors with lock motors for:

central locking
central locking and deadlocking (market dependent)
central locking, deadlocking and child-proof locking (market dependent) (option)
central locking and child-proof locking (option).

The central locking lock motor locks the door.

The deadlock lock motor (BLL) disengages the inner door handle. When the deadlock (BLL) is activated, the central locking switch (located in the driver's door control panel) is deactivated and reactivated when the vehicle is unlocked.

The child-proof lock motor is only for the rear doors and disengages the inner door handle.

The door control modules can only unlock the doors on receipt of a command from the central electronic module (CEM). In addition to the lock motors, the lock units contain up to three contract breakers depending on the configuration:

contact breaker to indicate that the central locking motor is in the locked position
contact breaker which indicates that the door is not locked
contact breaker to indicate the child-proof lock motor is locked.

To prevent the lock motors from becoming too hot, there is a protection function in the software in the central electronic module (CEM). The central electronic module (CEM) has a counter that counts a number of steps each time a central locking command is carried out. (The number of steps is determined by several parameters.)

The counter has a maximum value of 240 steps. Normally there are 12-13 activations in a row before the counter reaches the maximum value. The counter counts down by 1 step/second. If the counter has reached the maximum value, the central electronic module (CEM) will not perform commands for locking the central locking. The unlocking command will always be accepted, even if the maximum value has been reached. This means that if the central locking has been activated so many times that the counter has reached its maximum value, it will take about 5 seconds before the next central locking command is performed. The counter is fully restored after 4 minutes.

There is corresponding protection for the power child-proof lock motors