Additional Interfaces - Audi 243 Service Manual

Interfaces

Additional interfaces

The door contact signal ...
... is an earth signal from the control unit for
central locking. It indicates that the door or
boot lid/tailgate is open.
... serves as a "wake-up pulse" for transfer
from sleep mode to run-on mode (see
"Control concepts").
Terminal 50 signal...
... signals actuation of the starter and is used
to switch off the compressor during start-up.
If a low position is detected following a wake-
up pulse, the compressor is activated
immediately in order to allow the vehicle to
drive off as quickly as possible.
The compressor is switched off during start-
up in order to save battery power and ensure
starting power.
The vehicle locking signal ...
... is used as information for parking level
control
... is an earth pulse coming from the control
unit for central locking J429
... is not detected by the self-diagnosis.
Parking level control is not performed if this
signal fails.
The vehicle locking signal is not
required for vehicles without parking
level control (see pages from 10
onwards and 34 onwards).
30
The driving speed signal ...
... is a square-wave signal produced by the
dash panel, the frequency of which is
changed in accordance with the vehicle
speed.
... is required in the evaluation of the driving
condition (stationary/driving mode) and
thereby for selection of the control criteria
(see "Control concept").
The interface for the driving speed signal is
redundant, as the information regarding
speed is also transmitted by the CAN bus.
K wire
Communication for self-diagnosis between
control unit J197 and the diagnostic tester
takes place via the familiar K wire by means of
conventional data messages.
The self-diagnosis K wire must not be
confused with the K wire connecting
operating unit E281 to control unit J197.
Power supply to the headlamp range control
system
In the case of 4-level air suspension in the
allroad quattro, the headlamp range control
system voltage is supplied by the air
suspension control unit J197. Further
information can be found under Control unit
J197 on page 34.