air condition AUDI S4 1998 B5 / 1.G Engine Manual

11
Fan control
The control unit for radiator fan V293 regulates
the output of the radiator fan and controls the
continued coolant circulation. The induced-air
fan V7 and the forced-air fan V177 are
activated simultaneously.
Forced-air fan V177 is located upstream of the
condenser, water cooler and visco fan. It
assists the visco fan.
The electronic power control
The various fan settings are executed by an
electronic power control.
The fan motors are operated periodically, the
length of the operating cycle depending on the
fan setting selected. Fan output level is
controlled via pulse-width-modulated outputs.
Should a fan fail, the radiator fan control unit
increases the speed of the fan motor still
available.
Advantages of the power control:
•
The series resistors previously used for
power control are no longer required.
•
Lower power consumption in lower fan
settings.
•
Safety functions.
The power supply is protected by a
fuse on the 8-socket relay plate. For
the correct fuse rating, please refer
to wiring diagram.
Vehicles equipped with an air
conditioner require a higher fuse
rating than vehicles without an air
conditioner.
SSP 198/50

8-socket relay plate
SSP 198/55

Control unit for radiator fan
attached to front right
vehicle side member
Fuse, terminal 30
Fuse, terminal 61

12
Electric circuit of fan control:
Engine
for vehicles with air-conditioning system:
Integrated in the pressure switch for air
conditioner F129 is the high-pressure switch
for activating a higher fan setting.
The pressure switch is mounted below the
right-hand headlight behind the bumper.
Components:
F18/F54 Radiator fan thermoswitch
F95 Thermoswitch for continued coolant
function
F129 Pressure switch for air conditioner
(only for vehicles with air conditioner)
V293 Control unit for radiator fan
V7 Radiator fan (induced-air fan)
V51 Continued coolant circulation pump
V177 Fan 2 for radiator (forced-air fan)
(only for vehicles with air conditioner)
1 Terminal 30, positive supply via fuse
on 8-socket relay plate
2 Terminal 61, D+ (alternator) via fuse on
8-way relay
3 Fan activation (only for vehicles with
air conditioner)
M_
V293 F18
F54
F129
V177V7 V51
M_
M_
SSP 198/17
*
*
F95
*
P
P
123

only for vehicles with air conditioner
Air-conditioning pressure switch F129

13
Function of fan circuit
(for vehicles with air-conditioning
system)
4 fan settings are possible:
is activated by coolant pump thermoswitch
F95.
The fan motors and continued coolant
circulation pump V51 are activated.
The fan motors run at min. output (40%).
is requested by radiator fan thermoswitch F18
or by the air-conditioning control panel.
The fan motors run at 50% output.
is activated by air-conditioning system
pressure switch F129.
The fan motors run at 85 % output.
is activated by radiator fan thermoswitch F54.
The fan motors run at full output.
Fan speeds 1, 2 and 3 are only
activated if the “engine running“
signal is picked up at terminal 61.
The electrical coolant function.....
The continued coolant function is
only activated if the “engine not
running“ signal is picked up at
terminal 61. The continued coolant
function period is limited to 10
minutes.
Fan speed 1......
Fan speed 2......
Fan speed 3......

49
Sensors
Charge pressure sender G31
The charge pressure sender is located
upstream of the throttle valve control part.
The Motronic supplies the sender with a
voltage of 5 volts and earth.
The signal which the sender generates is a
pressure- proportional voltage ranging from 0
to 5 volts.
At atmospheric pressure (at sea-level), the
voltage is approx. 2.5 volts.
The signal is used for charge pressure control.
The Motronic also needs information on
charge pressure so that it can take counter-
measures if the maximum permissible
pressure is exceeded.
Substitute function and self-diagnosis:
If sender G31 fails, the charge pressure is
controlled via the characteristic curve (engine
speed-dependent). This will result in a
deficiency of engine power.
SSP 198/29
Charge pressure sender G31
The altitude sender F96 ....
... is integrated in the engine control unit, as is
normally the case with turbocharged engines.
... is required to control the charge pressure. In
conditions of decreasing air pressure (lower
density), the charge pressure is reduced to
prevent the turbocharger overspeeding.
... influences the air/fuel mixture composition
at engine start-up. The starting mixture is
leaned down with rising altitude.Substitute function and self-diagnosis
If a signal fails, the charge pressure is reduced
to a safe level, which results in a deficiency of
engine power.
Adaption of the injection quantity at start-up
no longer takes place.
The fault message “Control unit defective“ is
displayed in the self-diagnosis.
The following chapter presents the new features of the sensors, provided that they have not
already been described in the chapter on Subsystems of Motronic.

57
Additional signals/interfaces
Additional signals/interfaces to
Motronic ME 7.1
The Motronic receives a large number of
additional signals.
The following overview shows the signal
direction and meaning referred to the Motronic
control unit
Input
signalOutput
signalBidirec-
tionalSignal meaning
·CAN-high, data bus signal for automatic gearbox
·CAN-low, data bus signal for automatic gearbox
·CCS, “set/decelerate“ signal for cruise control system
·CCS, “Off“ signal for without cancellation cruise
control system
·CCS, “On/Off“ signal for with cancellation cruise
control system (master switch)
·CCS, “Resume/accelerate“ signal for cruise control
system
·Road speed signal
·Immobiliser/diagnosis signal
·Air conditioner compressor “On/Off“ signal
·Coolant temperature signal
·Engine speed signal
·Fuel consumption signal
The term “interfaces“ is used to
describe the control unit connections
and wiring connections of the various
control units.

58
Additional signals/interfaces
The road speed signal ...
... is required for operation of the cruise control
system, speed limiter, load change measures,
idling speed stabilisation and internal safety
checks of the control unit (e.g. adaption
conditions).... is a square-wave signal which is conditioned
by the dash panel insert. The frequency of this
signal changes as a factor of road speed.
The dash panel insert transfers 4 pulses per
revolution of the wheel.
Coolant temperature signal
The engine control unit receives from the dash
panel insert a coolant temperature signal
calculated from the signal which coolant
temperature sender G2 generates and a
related temperature characteristic.
The signal is a “data message“ and is
connected to the earth potential when a
temperature of approx. 120 °C is exceeded.
In this case, the air conditioner’s operating and
display unit switches the compressor off along
the bidirectional wire designated “Air-
conditioner compressor On/Off“.As of a temperature of 116 °C, the charge
pressure is reduced in order to counteract a
further rise in temperature.
If the temperature drops below a value of
approx. 116 °C, a data message is again
transferred and all actions previously
performed are reversed.
SSP 198/69
1 revolution of wheel Road speed signal (4 pulses)
Signal from speedometer sender (reed contact)

59
The “Compressor On/Off“ interface ...
... serves to provide the engine control unit
with information on the circuit state of the
compressor.
... enables the engine control unit to switch off
the compressor or inhibit start-up.
... provides a link to the air conditioner’s
operating and display unit.
The interface as a signal input:
Shortly before switching on the magnetic
coupling, the air conditioner’s operating and
display unit applies voltage to the interface.
The engine control unit then increases the
idling speed to compensate for the higher
engine load.The interface as a signal output:
If the engine control unit applies an earth
potential to the interface, the compressor is
switched off for a defined period of time as
required.
The engine control unit switches the
compressor off in the following situations:
- After initiating basic setting (function 04)
- In certain emergency running programs
within a defined engine speed range
The immobiliser/diagnosis interface ...
... is the communication link between the
engine control unit and the immobiliser in the
dash panel insert.... also serves as the diagnosis wire (K-wire) for
the diagnosis tester. Dialogue takes place via:
diagnosis plug Û dash panel insert interface Û
immobiliser/diagnosis interface Û engine
control unit

60
Additional signals/interface
The engine speed signal...
... is a square-wave signal which is conditioned
by the engine control unit and whose
frequency is synchronous with engine speed.
The duty factor is approx. 50%.
Three signals are transferred per revolution of
the engine.... is required by the following system
components:
- Dash panel insert
- Automatic gearbox
- Air conditioner
The CAN-high/CAN-low interfaces ...
... serve to transfer data between the control
units.
The CAN data bus (Controller Area Network) is
a serial data transfer system.You can find detailed information
regarding the CAN databus in SSP
186.
12
20 40 603
SSP 198/61
1 revolution of engineSegments of the sender wheel 3 signals

62
Functional diagram
Components:
F Brake light switch
F36 Clutch pedal switch
F47 Brake pedal switch
F96 Altitude sender (integrated in engine
control unit)
G2 Coolant temperature sender
G6 Fuel pump
G28 Engine speed sender
G31 Charge pressure sender
G39 Lambda probe (cylinder bank 1)
G40 Hall sender (cylinder bank 2)
G42 Intake air temperature sender
G 61 Knock sensor (cylinder bank 1)
G62 Coolant temperature sender
G66 Knock sensor (cylinder bank 2)
G70 Air mass meter
G79 Accelerator position sender 1
G108 Lambda probe (cylinder bank 2)
G163 Hall sender (cylinder bank 1)
G185 Accelerator position sender 2
G186 Throttle valve drive (electric throttle
control)
G187 Angle sender 1 for throttle valve drive
G188 Angle sender 2 for throttle valve drive
G235 Sender 1 for exhaust gas temperature
G236 Sender 2 for exhaust gas temperature
J17 Fuel pump relay
J220 Motronic control unit
J338 throttle valve control part
K132 Warning lamp for electric throttle
control
N Ignition coil, cylinder 1
N30 Injector, cylinder 1
N31 Injector, cylinder 2
N32 Injector, cylinder 3
N33 Injector , cylinder 4
N75 Solenoid valve for charge pressure
control
N80 Solenoid valve for activated charcoal
canister
N83 Injector, cylinder 5
N84 Injector, cylinder 6
N122 Output stage (cylinder bank 1)
N128 Ignition coil, cylinder 2
N158 Ignition coil, cylinder 3
N163 Ignition coil, cylinder 4
N164 Ignition coil, cylinder 5N189 Ignition coil, cylinder 6
N192 Output stage (cylinder bank 2)
N205 Camshaft adjustment valve 1 (cylinder
bank 1)
N208 Camshaft adjustment valve 2
(cylinder bank 2)
N249 Divert air valve for turbocharger
Z19 Heater for lambda probe
Z28 Heater for lambda probe 2
I To dash panel insert
II To dash panel insert (warning lamp)
Additional signals
1 CAN-high (automatic gearbox)
2 CAN-low (automatic gearbox)
3 „Set/decelerate“ signal for cruise
control system
4 “Off“ signal without cancellation for
cruise control system
5 “On/Off“ signal with cancellation for
cruise control system
6 Resume/accelerate“ signal for cruise
control system
7 Road speed signal
8 Immobiliser/diagnosis signal
9 Air conditioner compressor “On/Off“
signal
10 Coolant temperature signal
11 Engine speed signal
12 Fuel consumption signal
Colour codes:
Input signal
Output signal
Positive
Earth
Bidirectional