Bus messages
| Bus messages |
Serial means that the information is sent in ”packets” which are transmitted one after the other in rapid succession.
Most of the control modules in the Saab 9-3 are connected to the bus.
The buses consist of a P bus (Powertrain Bus) and an I bus (Instrument Bus). Both buses are connected to the MIU (Main Instrument Unit). The buses are electrically isolated from each other.
The diagnostic tool is not connected direct to the bus but communicates via the DICE, one of the control modules connected to the I bus, and so has access to all control modules connected to the bus.
The P-bus has a data transfer rate ten times higher than that of the I-bus. This is because the P-bus requires information with the least possible delay.
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 sent and varies between 10 milliseconds (0.010 seconds) and 1 second. Information is also sent out by the control modules whenever the information changes.
The information is transferred between control modules via two leads, bus+ (green lead) and bus- (white lead). The leads are twisted to reduce their sensitivity to electrical interference.
| SID uses the following information |
|
Information
|
Unit
|
Sensor system
|
Description
|
|
Position lights
|
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 STC |
The SID unit activates the type of sound requested via the bus.
|
|
LH Rear Light Broken
|
YES/NO
|
TWICE
|
The SID unit uses this information for a CHECK message.
|
|
RH 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.
|
|
Brake lights
|
ON/OFF
|
TWICE
|
The SID unit informs the driver via CHECK messages.
|
|
Horn
|
0 : 6 : 42 ms
|
TWICE
|
The SID unit uses the information from TWICE and activates the horn for the requested period of time measured in ms as confirmation of “TSL” locking (Theft Security Lock).
|
|
Text Message
|
Text Information
|
TWICE
ACC Audio STC MIU |
Text information from TWICE on the anti-theft alarm function, ACC on the current programming, audio display, lower fuel level from MIU, soft top status from STC and warning for overheated oil in the gearbox.
|
|
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.
|
|
Engine coolant temperature (petrol)
|
-40 - 215°C
|
Trionic
|
The SID unit uses the information to calculate DTE.
|
|
Engine Started (petrol)
|
ON/OFF
|
MIU
|
The SID unit uses the information to calculate “Engine Off Time”.
|
|
Fuel Consumed
Since Start (petrol) |
0-65535 ml
|
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 Start (diesel) |
0-65535 ml
|
PSG 16
|
The SID unit uses the information for calculations for the trip computer function.
|
|
Engine coolant temperature (diesel)
|
-40 - 215°C
|
PSG 16
|
The SID unit uses the information to calculate DTE.
|
|
Engine Started (diesel)
|
ON/OFF
|
PSG 16
|
The SID unit uses the information for the auxiliary heater and to calculate the “Engine off time”.
|
|
Oil level Low (diesel)
|
ON/OFF
|
PSG 16
|
The SID unit uses this information for a CHECK message.
|
|
Diagnostics communication
|
|
DICE
Diagnostic tool |
See 3:5 Bus and diagnostic 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.
|
|
Unit
|
Metric
Imperial (°F) Imperial (°C) US |
ACC
|
The SID unit uses the information to display the correct units.
|
|
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 the information when a button on the steering wheel is pressed (activated).
|
|
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 compartment
|
Lux
|
MIU
|
Used by the MIU to regulate the intensity of the indicator lamps.
|
|
Time engine switched off
|
Minutes
|
ACC
|
ACC uses the value to calculate the settings when starting.
|
|
Outdoor temperature
|
°C
|
ACC
TWICE DICE |
The SID unit sends out the information for use by other systems.
|
|
Diagnostics communication
|
-
|
DICE
|
See 3:5 Bus and diagnostic communication
|
|
SID buttons
|
Clear
Set Trip Down Trip Up Night Panel |
TWICE
|
Button status on the SID unit.
|
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