1996 BMW 525I TOURING turn signal

12
Level Control Systems
Camber Warning Switch (E32 AND E34 Touring)
The self-leveling suspension systems used in the E32 and the E34 Touring are equipped
with a camber warning switch. The switch is mounted on the right rear axle support and
connected through a rod to the semi-trailing arm.
The function of the switch is to warn the driver of an
overload condition or an unsafe driving situation.
If the switch detects a rear wheel camber of -3.5 deg.
A signal is sent to the check control module and dis-
played on the dash.
A time delay of 8 minutes is incorporated to prevent
the warning from being displayed while driving
through turns.
The E38 does not use the camber warning switch
due to the design of the rear suspension.

38
Level Control Systems
All control operations in advance / overrun mode are executed as long as pressure is avail-
able in the accumulator. When the accumulator is empty and the engine is turned off, con-
trol operations are directly driven by the compressor. User-activated changes of ride level
and filling of the accumulator are not possible.
Terminal 15
As soon as the ignition is turned on (terminal 15), the user is allowed to lower the ride level
as required.
However, it is still not possible to raise the ride level or fill the accumulator.
Ride level is compensated outside a narrow tolerance range of 10 mm upwards and 10 mm
downwards.
Engine "on"
Ride level compensation, raising and lowering the vehicle's ride height as well as filling the
accumulator are permitted when the engine is running. The compressor also starts up dur-
ing every control operation.
Ride level is still compensated outside the narrow tolerance range of ±10 mm.
As long as the vehicle is stationary, high speed filtered ride level signals are used to detect
a change of load. This allows the system to react immediately to changes in ride level.
As soon as the vehicle is travelling, it changes over to low speed filtered ride-level signals.
The system no longer reacts to bump movements caused by road surface unevenness. A
mean value is formed over a prolonged period of time, i.e. payload is only altered by the
progressive emptying of the fuel tank.
The high speed filter is not used until the vehicle is stationary again and a lid is opened. If
no lid is opened, the vehicle logically cannot be loaded or unloaded.
SleepWake-Up
Power Down
Watch Dog
Ignition “ON”Advance/
Overrun
VA = Load Cutout Signal
Sleep = Temporary Power Down of Control Unit
Wake-up = Activating the Control Unit
Watch Dog = Monitoring
Engine Off
Engine On
Engine Running
Terminal 15 “ON” VA up
VA Down
Terminal 15 “OFF”

39
Level Control Systems
Workshop Hints
If a threshold level is exceeded on all 4 wheels when the vehicle is stationary, the control
unit assumes that the vehicle has been raised on a workshop platform.
There are three possible reset conditions for workshop platform recognition:
 The original level values are undershot at all four wheels,
 A selection is made by button,
 A speed of >40 km/h is recognized for 3 s.
Vehicle jack
If the lowering speed at a wheel is too low during the lowering operation, the system
assumes that the wheel is jacked up. However, the downward velocity must be less than
a certain preprogrammed speed threshold. If the system detects a jacked wheel, it stores
the height of this wheel.
Car jack recognition is reset when the stored ride height is again undershot. When a trav-
elling speed of 40 km/h is maintained for at least 3 s, another control attempt is performed.
The car jack recognition can also be reset by button selection.
Please note that the system also controls ride height in diagnostic mode. For this reason,
Belt Mode must be activated before carrying out work on the system or before setting the
vehicle ride height.
Belt Mode:
Heights are fixed and are not compensated. If Belt Mode is set, the function LED is off. The
text message "ride-height control system inactive" appears in the instrument cluster.
Transport Mode:
The Transport Mode setting is for transportation purposes. When the ignition is turned on,
the message "ride-height control system inactive" appears. Heights are increased or
decreased depending on ignition key status, e.g. ride height is reduced when the vehicle is
lashed to a ship or train and raised when the "Engine on" signal is generated and when the
vehicle is transported on a transporter truck.
The correct ride height is set to ± 5 mm via "Activate components." The left and right ride
levels are set separately at the rear axle. The ride levels are then set at the front axle. The
left and right air springs are adjusted jointly for this purpose.
Following this, the new ride height for the front and rear axles is stored via the "Offset func-
tion."
Before replacing components, the system must be depressurized! This is done in the diag-
nostics via "control unit functions," "Component activation," "Pressure-relieve front axle/rear
axle." Repeat the activation procedure 6 times.

49
Level Control Systems
Post Mode
The Post-mode is adopted in order to compensate any inclination or to adjust the ride
height after driving and between the Pre-mode and Sleep mode.
The Post-mode is limited in time to 1 minute. The Post-mode is only executed if the engine
has been running before the system switches into this mode. If the engine has not been
previously running, the system switches directly from Pre-mode into Sleep mode.
The control operation is performed in a narrow tolerance band of +/- 6mm and is terminat-
ed at +/- 4mm. The fast signal filter is used.
In the event of an inclination (Kerb Mode), the control operation takes place for the nominal
heights applicable in this situation.
Pre-Mode
The Pre-mode is activated by the “Load Cutoff” signal (e.g. by opening the door or unlock-
ing with the remote control). The Pre-mode then stays set for 16 minutes and is restarted
with a change in status.
The ride height of the vehicle is monitored and evaluated with a wide tolerance band.
In Pre-mode, the vehicle is only controlled un to the nominal height if the level is significantly
below the nominal height. The control tolerance band is -40mm from the mean value for
the single axle air suspension and -20mm for the dual axle system. This control tolerance
ensures that the vehicle is only controlled up in the case of large loads in order to increase
the ground clearance prior to departure. Small loads give rise to small compression travel
and this is compensated only when the engine is started. This control setting helps reduce
the battery load.
With the single axle air suspension, the vehicle is controlled down when the mean value
derived from both ride height signals is > 0mm and one side is in excess of +10mm. With
twin axle air suspension, the vehicle is controlled down when one side is >15mm.
In this mode, only the mean value of the two height signals is considered when deciding
whether there is an need for control operation.
The control operation is executed as long as pressure is available in the accumulator. When
the accumulator is empty and the engine is turned off, the control operation is driven direct-
ly by the compressor. User-activated changes of ride level and filling of the accumulator are
not possible.
Control operations which were started in other modes are continued with the inner toler-
ance bands applicable to these modes.
There is no inclination identification in Pre-mode.