Bus communication
| Bus communication |
| P-bus and I-bus |
All the control modules in the Saab 9-5 are connected to the bus except those for the ABS and SRS.
The buses are divided into the Powertrain bus (P-bus) and the Instrument bus (I-bus). Both buses are connected to the main instrument unit (MIU). The buses are electrically isolated from each other.
The data transfer rate on the P-bus is ten times faster than on the I-bus.
All the information sent from one control module is accessible for all other control modules on the bus. The MIU is responsible for ensuring that information available on one bus is also available on the other bus.
The control modules send out information on the bus at regular intervals. The time between two transmissions depends on the information being transmitted and varies between 10 milliseconds (0.010 seconds) and one second. Information is also sent out by the control modules whenever the information changes.
Information is transmitted between control modules on two leads, BUS+ (green lead) and BUS- (white lead). Both P-bus leads are twinned to decrease sensitivity to electrical interference.
| Diagnostics |
In a bus system, all units must be able to communicate with each other. For example, the engine cannot start unless the TRIONIC control module can receive the immobilization information emitted by TWICE.
Permanent bus faults
All communication between Tech 2 and the bus-connected systems goes via DICE. Irrespective of which system is being contacted, Tech 2 and DICE will check to see that all the bus-connected systems in the car are activated and communicating. If any bus-connected control module is missing, Tech 2 will detect this. This means that all the bus-connected control modules are communicating correctly if there is no warning from Tech 2.
Intermittent bus faults
The Trionic control module and the transmission control module always check that all control modules from which they obtain information are communicating properly. If intermittent faults occur in bus communication, diagnostic trouble codes will be generated in the Trionic and transmission control modules. The cause of the fault may be that the control module concerned has lost its power supply or that one of the bus leads is disconnected.Incorrect values on the bus
Diagnostic trouble codes are set in Trionic and TCM if any information they receive from the bus has an incorrect value. The trouble code readout will refer to the faulty system.For further information on the bus, see Bus and diagnostics communication
| DICE uses the following information |
|
Information
|
Unit
|
Sensor system
|
Description
|
|
LH rear light
|
ON/OFF
|
TWICE
|
DICE uses the information for the instrument lighting.
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|
RH rear light
|
ON/OFF
|
TWICE
|
DICE uses the information for the instrument lighting.
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Driver's door
|
OPEN/CLOSED
|
TWICE
|
DICE uses the information to turn on/off the interior lighting.
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Passenger door
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OPEN/CLOSED
|
TWICE
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DICE uses the information to turn on/off the interior lighting.
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Passenger door, LH rear
|
OPEN/CLOSED
|
TWICE
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DICE uses the information to turn on/off the interior lighting.
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Passenger door, RH rear
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OPEN/CLOSED
|
TWICE
|
DICE uses the information to turn on/off the interior lighting.
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Boot lid
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OPEN/CLOSED
|
TWICE
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DICE uses the information to turn on/off the luggage compartment lighting.
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|
Hazard flashers
|
ON/OFF
|
TWICE
|
DICE uses the information to activate/deactivate the hazard flashers for the car's anti-theft alarm.
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|
A/C In
|
ON/OFF
|
ACC
|
DICE uses the information to activate/deactivate the car's A/C function.
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Electrically heated rear window
|
ON/OFF
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ACC
|
DICE uses the information to activate/deactivate the heating.
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Vehicle speed
|
km/h
|
MIU
|
DICE uses the information for the intermittent wiper function and the car's radiator fan system.
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|
Rheostat level
|
%
|
SID
|
DICE uses the information to control the brightness of the instrument and control lighting.
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|
Rheostat Night Panel
|
%
|
SID
|
DICE uses the information to control the brightness of the buttons when NIGHT PANEL is active.
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|
Night Panel
|
ON/OFF
|
SID
|
DICE uses the information on whether NIGHT PANEL is activated or deactivated.
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Display lighting
|
%
|
SID
|
DICE uses the information to control the brightness of the display.
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|
Outdoor temperature
|
°C
|
SID
|
DICE uses the information to control the radiator fan and A/C.
|
|
Engine Running
|
ON/OFF
|
Trionic
|
DICE uses the information to control the radiator fans.
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|
Coolant temperature
|
°C
|
Trionic
|
DICE uses the information to control the radiator fan and A/C systems.
|
|
Diagnostics
|
|
Tech 2
|
See Bus and diagnostics communication
|
| DICE sends the following information |
|
Information
|
Unit
|
User system
|
Description
|
|
A/C
|
ON/OFF
|
Trionic
|
Trionic uses the information to control relays.
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|
A/C pressure
|
bar
|
Trionic
|
Trionic uses the information for load compensation.
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|
Current consumption
|
A
|
Trionic
|
Trionic uses the information for load compensation.
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|
Idling speed increase
|
ON/OFF
|
Trionic
|
Trionic uses the information to detect “warm market”.
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|
Reverse gear
|
ON/OFF
|
PMM
|
PMM uses the information to adjust rear view mirrors.
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|
Position lights
|
ON/OFF
|
MIU, SID
|
MIU uses the information to turn on/off the position light indicator on the main instrument unit.
|
|
Rear fog light
|
ON/OFF
|
MIU
|
MIU uses the information to turn on/off the rear fog light indicator on the main instrument unit.
|
|
LH direction indicators
|
ON/OFF
|
MIU, SID
|
MIU uses the information to indicate activated LH direction indicators with the control lamp on the main instrument unit.
SID uses the information for acoustic indication of activated direction indicators “tick-tack”. |
|
RH direction indicators
|
ON/OFF
|
MIU, SID
|
MIU uses the information to indicate activated RH direction indicators with the control lamp on the main instrument unit.
SID uses the information for acoustic indication of activated direction indicators “tick-tack”. |
|
Rear fog light broken
|
YES/NO
|
SID
|
SID uses the information to display a CHECK message.
|
|
Sound
|
Sound information
|
SID
|
SID uses the information to generate acoustic warnings.
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|
Electrically heated rear window
|
ON/OFF
|
ACC
|
ACC uses the information to confirm that the rear window heating is active.
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VIN
|
Chassis number
|
Audio
|
Audio uses the information for the system's anti-theft protection.
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|
Ignition +B
|
ON/OFF
|
Audio, TWICE
|
Informs Audio and TWICE on the position of the ignition switch.
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|
Ignition +15
|
ON/OFF
|
TWICE
|
Informs TWICE of the position of the ignition switch.
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Ignition +54
|
ON/OFF
|
TWICE, ACC
|
Informs TWICE of the position of the ignition switch.
|
|
Ignition +50
|
ON/OFF
|
TWICE
|
Informs TWICE of the position of the ignition switch.
|
|
Diagnostics
|
|
Tech 2
|
See Bus and diagnostics communication
|
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