display BMW 525I TOURING 2003 E39 Level Control System Manual

7
Level Control Systems
Oil Reservoir
The single reservoir stores fluid for both the self-leveling and power steering systems.
Incorporated in the reservoir, is a reed type level warning switch. If the fluid level drops and
the contact closes, a signal is sent to the check control module and a warning will be dis-
played in the instrument cluster matrix display.
The hydraulic fluid required for the self-leveling suspension system varies between models
and installed equipment. The following fluid is used:
 Pentosin CHF 7.1
 Pentosin CHF 11S
 Power Steering Fluid (BMW)
This type of fluid is used because of its
low viscosity and low noise characteris-
tics. It cannot be mixed with other fluid
types.
The self-leveling system fluid type is
always marked on the top of the hydraulic
reservoir. Always use the correct fluid
never mix with another fluid.
When filling the system, be aware of the
status of the level control system. If the
vehicle is loaded, the level will appear to
be low. Do not fill the system unless it is
in the resting state. Otherwise, an over-
flow situation could result.

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.

17
Level Control Systems
Air Springs
The air spring is made from a flexible rubber material. It
forms an air tight cavity which provides the calculated
spring rate required for the sport wagon.
As the spring compresses downward the bottom edge
of the rubber material rolls along the vertical surface of
the base mount cylinder.
Air is added or removed from the air spring through its
top port. The top port of each spring is connected to a
reservoir and the air supply pipes. The reservoirs are
required to hold additional air due to the compact design
of the springs.
Rear Axle Level Sensors
Hall effect sensors are mounted on the left
and right sides of the rear suspension for
ride height detection. They are pivoted by a
coupling rod through the rear axle swing
arms.
The hall sensors produce a varying voltage
input to the control module as the suspen-
sion height changes.
If the vehicle is equipped with Xenon head-
lights the right side sensor contains an
additional sensor for the automatic head-
light level adjustment system.
Warning Displays
If the system is faulted and off-line or set in the transport mode, the following is displayed:
Basic Cluster:A warning lamp indicator is illuminated used on the basic cluster.
High Cluster: A message is posted in the high cluster matrix display.
E39 Features 07

23
Level Control Systems
Special Operating Modes
Assembly Line Mode (New control module)
The assembly line mode refers to control module manufacturing. New control modules
are stored in a deactivated state. The control programming is not active and must first
be ZCS encoded.
After installing a replacement control module, it must be coded using the DIS or MoDiC.
The instrument cluster fault display will remain illuminated until the control module is
coded.
Transport Mode
The vehicle rolls off the factory assembly line with the EHC control module in the trans-
port mode. The transport mode inflates the air springs to a higher position (approx.
30mm higher) than the normal mode in order to avoid damage during transit.
The system will not respond to any inputs that would alter the height of the vehicle. The
fault indicator (base cluster) is illuminated or instrument cluster matrix display (high clus-
ter) provides the message “Leveling System” to draw attention to the transport mode
setting.
The Service Functions section of the diagnosis program is used to activate/deactivate
the transport mode. Once the transport mode is deactivated, check the vehicle Ride
Height Offset making sure the vehicle rear axle height is to specification.
Control Interrupts
Cornering
To prevent unnecessary suspension adjustments while driving through corners, a “control
interrupt” is built into the system. Above 30MPH the control module monitors the left/right
ride height sensors for a difference of 30mm. Exceeding this difference will put the system
into a control interrupt and no adjustment will take place. The control interrupt last for a
duration of 5 minutes.
Vehicle Lifting
The ride height control is interrupted when the vehicle is raised on a lift or with a jack. The
system monitors the ride height sensor inputs and when the height limit of 90 mm is
exceeded, the control is switched OFF until the vehicle is lowered again.

24
Level Control Systems
EHC Service Information
Diagnosis/Coding
 The EHC control module is connected to the diagnostic link. The EHC control module
activates the fault display in the instrument cluster to alert the operator of the off-line sta-
tus of the system. The EHC control module stores up to three electrical/electronic
faults.
 Diagnosis/troubleshooting of EHC is carried out using the fault symptom troubleshoot-
ing program of the MoDiC or DIS. The EHC system has an extensive diagnosis program.
 Replacement control modules are shipped in the factory mode. The control modules
must be ZCS encoded using the DIS or MoDiC to activate the operating parameters.

37
Level Control Systems
In addition to the LED indicator, the following text messages can
be displayed in the instrument cluster:
T TR
RA
AI
IL
LE
ER
R
M
MO
OD
DE
E
A coupled trailer is identified via the trailer connector. To avoid damaging the trailer and
the vehicle, changes of vehicle level are generally avoided. The standard level is "frozen."
If the trailer is coupled at a level other than the Standard level, the vehicle ride level is
not changed to Standard unless a button is pressed or the speed threshold for auto-
matic change-over is reached. The standard level is then "frozen" until the trailer con-
nector is disconnected.
R RI
ID
DE
E
H
HE
EI
IG
GH
HT
T
C
CO
ON
NT
TR
RO
OL
L
I
IN
NA
AC
CT
TI
IV
VE
E
Faults in the system and on the control unit which are only identified by the instrument
cluster, e.g. control unit disconnected
R RI
ID
DE
E
H
HE
EI
IG
GH
HT
T
C
CO
ON
NT
TR
RO
OL
L
I
IN
NA
AC
CT
TI
IV
VE
E
+
+
M
MA
AX
X.
.
6
60
0
k
km
m/
/h
h
For safety-critical faults (vehicle is too high or at inclination)
Control Modes
Sleep mode
If the vehicle is parked, it enters Sleep mode after 16 minutes. No further control opera-
tions are executed. A "watch dog" wakes up the control unit for a few minutes every 6
hours (wakeup mode) in order to compensate for possible inclination of the vehicle. (Vehicle
height may only be corrected once as air supply unit only operates with engine running.)
Wake-up
In wake-up mode, the control unit is woken up for a set period of time in order to com-
pensate for possible inclination of the vehicle. Inclination of the vehicle can be caused by
large temperature differences or by minor leaks. Adjustments to the front and rear axles
ensure that the vehicle is visually level. To minimize power consumption, the vehicle is low-
ered only. The nominal level of the lowest wheel serves as the nominal level for all other
wheels. The lowest nominal level to which the vehicle is lowered is the Access level (-35
mm).
Exception:if the vehicle is parked at Access level, the vehicle is lowered to max. -50 mm
in wake-up mode. If the vehicle is parked for a prolonged period of time and there is a leak
in the system, further loss of pressure does not produce a change of ride level since the
weight of the body is born by the auxiliary suspension and the residual tire pressure.
Advance /Overrun
When the vehicle is woken out of sleep mode by the load-cutout signal (VA), it normally
enters advance / overrun mode. Since the engine is not (no longer) running in this mode,
however, there are restrictions on the control operations that can be performed in order to
conserve the battery. Ride level compensation is restricted to tolerance ranges of 20 mm
and 25 mm in the up and down directions respectively. This serves to reduce the frequen-
cy of control operations.

41
Level Control Systems
Single Axle Air Suspension (E65/E66)
Purpose of the System
The single axle air suspension system used on the the E65/E66 is a further enhancement
of the previous single axle air suspension system used on the the E39 and X5. The com-
ponents used are similar to the Single Axle EHC System on the E53. The E65/E66 Air sus-
pension consists of the following components:
 Air Supply System (LVA)
 Control Unit (EHC)
 Two Air Springs
 Two Ride Height Sensors
 CC Display/Telltale Icon

44
Level Control Systems
Control Unit
The EHC control module is located in the right rear luggage compartment area in the mod-
ule carrier next to the battery. On the E65/E66, the control module is connected to the K-
CAN S. The EHC control module receives the following information:
 Vehicle Ride Height
 Load Cutout Signal
 Terminal 15 ON/OFF
 Vehicle Speed
 Lateral Acceleration
 “Engine Running” Signal
 Flap Status (Doors/Trunk)
The Control unit decides on a case by
case basis whether a control opera-
tion is required in order to compen-
sate changes in load. It prevents
intervention in the case of other caus-
es. This makes it possible to adapt
the frequency, specified height, toler-
ance thresholds and battery load opti-
mally by means of the control opera-
tion to the relevant situation.
In addition to handling the self levelling
suspension, the control module moni-
tors the system components as well
as storing a displaying faults. The
control module has full diagnostic
capability.
The EHC module is a 26 pin module
with an ELO type connector. The
module is connected to the K CAN S.
The majority of the input messages
are from the K CAN S Bus.
EHC Module Location

46
Level Control Systems
Ride Height Sensor
There are two ride height sensors, one for each rear wheel. The ride height sensor is actu-
ated by a coupling rod and sends a signal to the EHC control unit.
The sensor is a hall sensor which sends a DC Analog output voltage to the EHC module.
The voltage range is approximately .5 to 4.5 volts. The voltage increases with increasing
vehicle height and the nominal voltage at normal ride height is approximately 2.5 volts. The
right side rear sensor is a double sensor, the additional sensor is an input to the headlight
leveling systemand has it’s own power supply, ground and signal wires.
Check Control Messages
Control
UnitCauseVariable
Telltale IconCheck Control
MessageInformation in Control Display
EHC
Alive failure or
loss of function-
ality; transport
or belt mode setLevel Control
System failure“Level Control system failure”
Ground clearance and driving
comfort reduced. Avoid high
speed cornering. Have
checked by BMW Service as
soon as possible.
EHC
Level Control
System sensor
failure.Level Control
System Fault“Level Control System fault”
Possible reduction in driving
comfort. Have problem
checked by BMW Service.

52
Level Control Systems
Lift
The Lift mode is used to prevent control operations when a wheel is changed or during
work on the vehicle while it is on a lifting platform.
This mode is recognized when the permitted rebound travel at one or more wheels is
exceeded. For the E65/E66 the limit is > 55mm.
A “jack” situation is also recognized when the ride level is stored and the lowering speed
drops below the value of 2 mm/s for 3 seconds.
If the vehicle has been raised slightly and the permitted rebound travel has not yet been
achieved, the control operation attempts to readjust the ride height. If the vehicle is not low-
ered, a car jack situation is recognized after a specific period of time and this ride height is
stored.
A reset is performed if the vehicle is again 10 mm below this stored ride height.
Transport
The Transport mode is set and cleared by means of a diagnosis activation. It serves to
increase the ground clearance in order to ensure a safe transportation of vehicles on trans-
porter trucks. The nominal height of the vehicle is raised in this mode by 30 mm.
When the Transport mode is activated, the air suspension symbol is indicated in the vari-
able telltale in the instrument cluster and a text message is output in the Check Control
Display.
Control operations do not take place in this mode because the vehicle mass does not
change during transportation.
Belt
The Belt mode is set for mounting on the belt in order to avoid control operations.
When the Belt mode is activated, the air suspension symbol is indicated in the variable tell-
tale in the instrument cluster and a text message is output in the Check Control display.
The Belt mode is cleared by means of a diagnostic activation only. The Belt mode can no
longer be set.
New control units are supplied with the Belt mode set.
Control operations are not performed, the safety concept only operates with limited effect.
The Belt Mode is also known as “Band Mode” or “Assembly Line Mode”.