Bus communication
| Bus communication |
| P-Bus and I-Bus |
In the Saab 9-5, all the car's control modules are connected to buses with the exception of the ABS and SRS control modules.
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 P-bus has a data transfer rate ten times higher than that of the I-bus.
All information sent out on a bus by a control module is available to all other control modules connected to the bus. The MIU ensures that the information which is available on one bus is also available on the other.
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 transfer between control modules takes place on two leads, BUS+ (green lead) and BUS- (white lead). On the P-bus the leads are twisted to reduce 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 sent out by TWICE.
Permanent bus fault
All Tech 2 communication with systems connected to the bus takes place through DICE. Irrespective of which system is contacted, Tech 2 via DICE first checks that all on-board systems connected to the bus are turned on and communicating. If any control module connected to the bus is missing, Tech 2 will show this. This means that all control modules connected to the bus can communicate correctly unless Tech 2 warns otherwise.Intermittent bus fault
The Trionic control module and the transmission control module (TCM) continuously check that all control modules from which they obtain information are communicating correctly. 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 power or one of the bus leads is disconnected.Incorrect values on the bus
A diagnostic trouble code will be generated in the Trionic and transmission control modules if any information they obtain from the bus is incorrect. The trouble code text indicates the system where the fault has occurred.For further information on the bus, see Bus and Diagnostics Communication.
| SID uses the following information |
|
Information
|
Unit
|
Sensor system
|
Description
|
|
Position light
|
ON/OFF
|
DICE
|
The SID unit uses this information to calculate the rheostat value.
|
|
Rear fog light broken
|
YES/NO
|
DICE
|
The SID unit uses this information for a CHECK message.
|
|
LH direction indicators
|
ON/OFF
|
DICE
|
The SID unit activates TICK-TACK for the direction indicator function.
|
|
RH direction indicators
|
ON/OFF
|
DICE
|
The SID unit activates TICK-TACK for the direction indicator function.
|
|
Sound
|
Acoustic information
|
DICE, TWICE, ACC
Audio, MIU PSM |
The SID unit activates the type of sound requested via the bus.
|
|
Left rear light broken
|
YES/NO
|
TWICE
|
The SID unit uses this information for a CHECK message.
|
|
Right rear light broken
|
YES/NO
|
TWICE
|
The SID unit uses this information for a CHECK message.
|
|
Left brake light
Broken |
YES/NO
|
TWICE
|
The SID unit uses this information for a CHECK message.
|
|
Right brake light
Broken |
YES/NO
|
TWICE
|
The SID unit uses this information for a CHECK message.
|
|
High level brake light
Broken |
YES/NO
|
TWICE
|
The SID unit uses this information for a CHECK message.
|
|
Test brake lights
|
ON/OFF
|
TWICE
|
The SID unit tells the driver via the CHECK message to press the brake pedal. (Some markets only)
|
|
Horn
|
0 : 6 : 42 ms
|
TWICE
|
The SID unit uses the information from TWICE and activates the horn for the requested time in ms as acknowledgement of “TSL” locking.
|
|
Text Message
|
Text information
|
TWICE, ACC
|
Text information from TWICE concerning the anti-theft alarm function, from the ACC concerning user programming, audio display and high gearbox oil temperature warning.
|
|
RDS time
|
Hours,
minutes, seconds |
Audio
|
The SID unit uses the information in the time function (clock).
|
|
RDS date
|
1-31
|
Audio
|
The SID unit uses the information in the time function (clock).
|
|
RDS month
|
January -
December |
Audio
|
The SID unit uses the information in the time function (clock).
|
|
Vehicle speed
|
km/h, mph
|
MIU
|
The SID unit uses the information for calculations for the trip computer function.
|
|
Fuel level
|
litres
|
MIU
|
The SID unit uses the information for calculations for the trip computer function.
|
|
Odometer reading
|
km, miles
|
MIU
|
The SID unit uses the information for calculations for the trip computer function.
|
|
Fuel consumed
Since starting |
0- 65535 ml
|
Trionic
|
The SID unit uses the information for calculations for the trip computer function.
|
|
Engine Started
|
ON/OFF
|
Trionic
|
The SID unit uses the information to calculate “Engine Off Time”.
|
|
Coolant temperature
|
-40 - 215°C
|
Trionic
|
The SID unit uses the information to calculate DTE.
|
|
Diagnostics communication
|
|
DICE
|
See Bus and Diagnostics communication.
|
| The SID sends out the following information |
|
Information
|
Unit
|
User system
|
Description
|
|
Info Disp Lamp
|
ON/OFF
|
MIU
|
The MIU lights the lamp on request from the SID.
|
|
Language
|
Swedish, English,
German, French, Italian, Spanish |
ACC
|
The SID unit sends out information on the language selected.
|
|
Steering wheel controls
|
VOL -,
VOL +, SRC, SEEK >>, << SEEK, NXT, |
Audio
|
The SID unit sends out information when a button is pressed (activated) on the steering wheel controls. Applicable if the car has the Saab Audio System.
|
|
Rheostat level
|
0- 100%
|
Audio,
ACC, DICE, MIU |
The SID unit sends out information for regulating the instrument and control lighting.
|
|
Rheostat Night Panel
|
0- 100%
|
Audio,
ACC, DICE, MIU |
Rheostat level less a fixed value. Used for button lighting.
|
|
Night Panel
|
ON/OFF
|
Audio,
ACC, DICE, MIU |
The Night Panel function is activated and deactivated.
|
|
Display lighting
|
0- 100%
|
ACC,
MIU |
Lighting level for all displays. The highest rheostat or light sensor level.
|
|
Light intensity in the car
|
Lux
|
MIU
|
Used by the MIU to regulate the intensity of the indicator lamps.
|
|
Engine Off Time
|
Minutes
|
ACC
|
ACC uses the value to calculate the settings when starting.
|
|
Outside temperature
|
°C
|
ACC,
TWICE, DICE |
The SID unit sends out the information for use by other systems.
|
|
Diagnostics communication
|
-
|
DICE
|
See Bus and Diagnostics communication.
|
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