5 Series E61 523i (N52) TOUR
Sleep mode
No regulation is performed in sleep mode. Control functions that were started in other control modes are
cancelled when sleep mode is activated.
Pre-mode
In pre-mode (temporary start/run-on), changes in load are equalised even as the vehicle occupants are
getting in and then again for a certain time (approx. 20 minutes) after the vehicle is shut down.
In pre-mode, the ride height is only regulated to the specified height if it differs significantly from this height.
The tolerance range for regulation is approx. 40 millimetres under the mean value (the tolerance range
stipulates when the electronic circuitry in the EHC control unit performs regulation).
This tolerance ensures that regulation is only initiated for large loads, to increase ground clearance before
pulling away. Small loads produce smaller amounts of spring travel, which are not equalised until the engine
is started. These control characteristics reduce load on the battery.
In pre-mode, only the mean value of the two level sensor signals is considered.
Post-mode (readjustment)
Post-mode is used to equalise any inclination before sleep mode is initiated (fast filtering).
Control function is time-limited (approx. 1 minute).
In post-mode, regulation is restricted to a defined tolerance range (+7/-10 mm).
Normal mode
Normal mode refers to the normal operating conditions for the vehicle. Normal mode is initiated by the
"engine running" signal. Regulation is performed within a defined tolerance range on each side (
±
10 mm,
fast filtering).
Drive mode
If a roadspeed signal greater than 1 km/h is detected, the EHC control unit will switch to drive mode.
In drive mode, regulation employs slow filtering. For example, in drive mode, changes in ride height caused
by the reduction in the vehicle's weight due to fuel consumption are equalised.
Cornering
The "cornering" control function prevents adjustments being made when cornering is detected. Slow
filtering is suspended and ongoing regulation sequences suspended. Cornering is detected from an
incoming transverse acceleration signal (e.g. cornering greater than 2 m/s
2
, less than 1.4 m/s
2
when
leaving bend). The DSC control unit transmits the transverse acceleration signal via the K-CAN.
Twist
"Twist" mode prevents equalisation of an inclination caused by driving over an obstacle with one wheel.
Equalisation would cause a new inclination after the vehicle is driven off the obstacle, making a new
regulation sequence necessary.
If the vehicle is driven onto the kerbstone and stopped, the EHC control unit will switch from drive mode to
normal mode. In this control function, the signals from the left and right level sensors are evaluated.
"Twist" control function is activated if the difference in height between the left and right-hand sides exceeds
a certain value (e.g. 28 mm).
In this control function, the vehicle's ride height in the middle of the axle is evaluated by the EHC control
unit.
If the vehicle is loaded or unloaded, the degree of spring deflection is considered. If this value is outside the
defined tolerance range (e.g.
±
10 millimetres), regulation is initiated.
SBT Single-axle electronic height control E61, E70, E71
BMW AG - TIS
06.02.2013 00:51
Issue status (12/2007) Valid only until next DVD is issued
Copyright
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