Automatic Soft-Close Function (SCA)
Functional Description:
General Block Diagram:
General:
The automatic soft-close function enables automatic closing and opening of the security locks on all doors and on the rear lid.
All locks are connected to servo drives (electric motors). The servo drive is switches on via a relay when the door to be closed is pressed beyond the first detent position (Initial detent position) against the locking pin. The turn-catch is turned and the door closed.
Caution!
Danger of Injury!
The servo drives produce very high closing forces!
Reaching into the turn-catch as it is turning can cause severs injuries!
Objects which fall into the turn-catch can be damaged or may cause damage to the vehicle!
The system also operates when the ignition is switched off!
Therefore!
On no account turn the turn-catch by hand or with a tool in the "close" direction!
When performing all work on the turn-catch lock, disconnect the battery or deactivate the system by disconnecting the modules!
Modules:
Control Module (SM):
Installation location: Module support bracket above the rear axle (in luggage compartment).
The control module (SM) contains the entire electronic circuitry of the system. It controls and monitors the functional sequence.
Relay Module (RM):
Installation location: Module support bracket above the rear axle (in luggage compartment).
The relay module (RM) contains the relays for the turn-catch lock drives. All relays in the relay module are monitored for defects by means of diagnostic feedback (diagnostic links) to the control modules. A defect code is stored in the defect code memory when a defect is detected.
A relay is assigned to each drive. It is switched on until the motor has reached its relevant end position (feedback from limit switch). Normally, the direction of rotation of the motor is the same for both closing and opening.
A reversing relay is additionally provided for the two function groups (group 1: Driver's door, group 2: Other doors and rear lid). It is connected when the control module detects blocking of the drive and reverses the polarity of the turn-catch lock drive - the direction of rotation of the motor changes.
Turn-Catch Lock Drives:
The turn-catch lock drives are electric motors which are connected directly to the turn-catches. Normally, the direction of rotation is the same for closing and opening. The corresponding end position is sensed by a limit switch.
The direction of rotation is only changed when the closing procedure is obstructed. The obstruction is detected by the control module in that the "closed" position is not reached within a certain period of time. The relay for reversing the motor is then activated by the control module. The servo drive changes its direction of rotation and opens the door.
Important!
Due to the high closing forces, only very hard objects can obstruct the closing procedure. Even the car body may be damaged by jammed objects. Under no circumstances whatsoever must attempts be made to reverse the operation of the motor by jamming in hard objects!
Switches:
Microswitches in safety turn-catch lock
Four microswitches are necessary for the functional sequence. All switches switch to positive (B+).
S1 Door Handle Switch (not illustrated):
Installation location: Above the turn-catch lock.
The door handle switch is operated by means of the Inside or outside door handles. When a door handle is raised, the switch switches B+ to the control module. The lock servo drive is switched on and moves to the "open" end position.
Raising the door handle does not open the turn-catch when the vehicle has been locked by means of the central locking system or the vehicle speed is greater than 5 km/h.
S2 Turn-Catch Switch:
Installation location: In safety turn-catch lock (see Fig.).
The turn-catch switch is operated when the vehicle door is pressed beyond the first detent position. The switch signals to the control module that the servo drive is to be activated. The turn-catch is turned in the "close direction.
S3 Limit switch:
Installation location: In safety turn-catch lock (see Fig.).
The limit switch is operated by a trip cam which is connected directly to the servo drive. By way of the switch position, the control module senses the end position which the servo drive has assumed.
S4 Initial Detent Switch:
Installation location: In safety turn-catch lock (see Fig.).
The command "close turn-catch" can only be triggered when the door was completely open for a short period of time after opening the door.
By way of the initial-detent switch, the control module detects that the driver's door has been opened, i.e. the turn-catch has been completely turned out of the locking pin.
Notes:
Mechanical System:
Opening the driver's door uncouples the turn-catch from the servo drive when the door handle is raised beyond the mechanical detent point. The turn-catch snaps open irrespective of whether the lock servo drive is activated or not. This feature makes it possible to open and close the door even in the case of system failure.
Central Locking System:
When the vehicle has been locked by means of the central locking system, raising the door handle or pressing the rear lid catch does not cause the turn-catch to open.
Driving:
The SCA system is deactivated at a vehicle speed greater than 5 km/h. Electrical opening/closing of the turn-catches is therefore not possible.
Due to the fact that the mechanical and electrical systems are uncoupled, all doors can be opened while driving. The turn-catch is opened mechanically after raising the door handle beyond the mechanical detent point.
Defect Detection:
The control module constantly monitors all components of the system. If a defect occurs which could endanger safe operation, the module switches off either the faulty servo drive or the entire system.
Operation is resumed when the defect has been rectified and the defect code memory of the system has been cleared by means of the BMW DIAGNOSTIC SYSTEM or by disconnecting the battery.
Refer to "Troubleshooting" for the scope of the defect monitoring facility and the system responses.
Description of On-Board Diagnostic System