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6 WUP, wake-up line
7 PT-CAN input with terminal resistor
8 Power supply for EMF control unit (Terminal 30)
9 Power supply for electric motor (Terminal 30)
10 Earth for EMF control unit
11 Earth for electric motor
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F01 Longitudinal Dynamics Systems
Force sensor
Technically speaking, the force sensor is a travel sensor that operates according to the
Hall effect. Between the two brake cables there is a spring with a defined strength. That
strength is stored on the EMF control unit. Therefore, it can determine the force acting
on the cables from the change in the length of the spring.
The force acting on the brake cables is an important input variable for the control algo-
rithm on the EMF control unit. When the parking brake is applied, the EMF control unit
has to ensure that a specific required force is applied to the brake cables. The EMF con-
trol unit calculates that required force on the brake cables directly from the legally required
holding force on the wheels. The latter has to be great enough to safely keep the vehicle
stationary on an uphill or downhill gradient of up to 20 %.
Over the life of the cables, a slight degree of stretching can occur. However, that does not
corrupt the force-sensor signal. The spring does not, of course, start to compress until a
force is acting on the cables. If, due to stretching, the cables are initially loose when in the
released position, then no force is acting on the spring. Only when a force is applied to
the cables, and, therefore, to the spring by operation of the electric motor does the spring
compress. Then the force sensor sends the appropriate signal to the EMF control unit.
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F01 Longitudinal Dynamics Systems
Bracket
To attach the EMF actuator unit to the vehicle s structural components, a multi-angled
bracket is used. That design allows the EMF actuator unit itself to remain virtually identi-
cal in dimensions (to the one on the E70/ E71). Adaptation to the geometry of the
surrounding components on the different vehicles is achieved by the specific design of
the mounting bracket.
The bracket for the EMF actuator unit locates at the top on a boss on the rear suspension
subframe. Fixing of the bracket at the bottom differs according to whether the vehicle is
fitted with Integrated Active Steering or not. Vehicles with Integrated Active Steering have
an actuator for the rear-wheel steering on the rear suspension. The bracket for the EMF
actuator then rests on the rear-wheel steering actuator bracket. The two brackets are
joined by two bolts.
EMF actuator unit bracket and HSR actuator
Index Explanation Index Explanation
Bolt joining EMF actuator and
1 Left brake cable 5
HSR actuator brackets
2 Sleeve nut for left brake cable 6 HSR actuator bracket
3 Boss on rear suspension subframe 7 EMF actuator unit bracket
4 EMF actuator unit 8 Emergency release cable
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F01 Longitudinal Dynamics Systems
On vehicles without Integrated Active Steering, the bracket for the EMF actuator unit is
attached to the rear suspension subframe by the same two bolts.
EMF actuator unit bracket without HSR actuator
Index Explanation Index Explanation
Bolt fixing EMF actuator to rear
1 Bowden cable, emergency release 6
suspension subframe
2 Left brake cable 7 EMF actuator unit bracket
3 Sleeve nut for left brake cable 8 Rear suspension subframe
4 EMF actuating unit 9 Track rod
5 Bolt fixing EMF actuator to mounting bracket
The bracket and the EMF actuator unit itself are also attached to one another by bolts.
If replacement is necessary, both the bracket and the EMF actuator unit itself can be
ordered as separate parts.
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F01 Longitudinal Dynamics Systems
Controls
Parking Brake Button
The parking brake button supplies the EMF control unit with the button operation signal.
The signal is duplicated on the parking brake button and transmitted to the EMF control
unit via double direct wired connections. It not only enables the EMF control unit to dis-
tinguish between the resting position and the two directions of operation (release/apply).
Faults can also be detected (e.g. broken circuit, short circuit). If such a fault is detected,
the function of the parking brake can still be maintained in most cases.
Parking brake button with function indicator lamp
In contrast with the button on the E70/E71, the parking brake button on the F01/F02 has
a function indicator lamp. It is an LED that tells the driver when the parking brake is on.
The EMF control unit directly controls that LED.
It is important to note that the button directly behind it for the Automatic Hold function is
not wired to the EMF control unit but to the DSC control unit.
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F01 Longitudinal Dynamics Systems
Emergency release
The cable for emergency release of the parking brake is accessible via the trunk.
However, the cable is located underneath the trunk floor trim, which on the F01/F02
can not be simply taken out.
Removing trunk floor trim on F01/F02
Index Explanation
1 Plastic nut (size 10mm)
2 Emergency release tool
3 Trunk floor trim
Under a flap there are two plastic nuts which fix be removed. The emergency release tool
(red the trunk floor trim in place. Those nuts must T-shaped handle) incorporates a plastic
first be undone before the trunk floor trim can socket for unscrewing the nuts.
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F01 Longitudinal Dynamics Systems
Emergency release tool on F01/F02
Index Explanation
1 Slot for accepting the EMF emergency release cable
2 Socket (size 10mm) for unscrewing the plastic nuts on the trunk floor trim
3 Square key for releasing the automatic transmission parking lock
Once the trunk floor trim has been removed, the emergency release cable is directly
accessible. The handle of the release tool is hooked onto the end of the emergency
release cable by means of the slot provided.
Pulling the cable up operates the emergency release mechanism in the EMF actuator
unit. There is a noticeable jolt when it releases. The cables to the two duo-servo parking
brakes are then released from the force acting on them. The parking brake is thus
released.
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