Control Strategies; Control Strategies, Control Unit 4Z7 907 553A - Audi 243 Service Manual

Control strategies

There are two control units currently in use,
depending on the country.
The control strategies described below relate
to the control unit 4Z7 907 553A.
The differences in control units with part
numbers 4Z7 907 553B are described
subsequently.
See also page 34, "Self-levelling control unit
J197".
Control strategies
4Z7 907 553A
Automatic lowering
As mentioned previously, the driver can select
the appropriate level by actuating the "raise"
or "lower" buttons.
The following preconditions relating to
driving speed apply for high level 1 and high
level 2.
HL2
HL1
NL
LL
0
HL2
HL1
NL
LL
0 5
10
35 80 120
Speed km/h
35 70 120
Speed km/h
If the vehicle is at high level 2, it will lower
automatically to high level 1 at a speed of
> 35 km/h. The system will respond to a
request to shift to high level 2 only up to a
speed of < 30 km/h.
At a speed of > 80 km/h in high level 1, the
system will automatically lower the vehicle to
normal level.. The system will respond to a
(manual) request to shift to high level 1 only
up to a speed of < 75 km/h.
During driving operation, no automatic
raising to high level 1 or 2 is performed. It
must be selected manually by the driver.
The parking level is an exception. In this
mode the vehicle automatically rises to high
level 1 once it has been parked and locked
(see parking level control).
Lowering processes
Automatic lowering
after 30 seconds
243_026
Raising processes
after 30 seconds
after 120 seconds
Raising to parking level
Immediate raising