Bus messages
| Bus messages |
| P-bus and I-bus |
A bus is understood to be the leads over which information is sent digitally and serially. Digital means that the voltage difference between the leads has only two values, roughly 0 V and 5 V. The information is coded so that different combinations of 0 V and 5 V pulses have different meanings.
Serial means that the information is sent in ”packets” which are transmitted one after the other in rapid succession.
The bus is divided into 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.
As in the 9-5, the Airbag and ABS control modules are not connected to the bus.
The diagnostic tool is not connected directly 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 data transfer rate on the P-bus is ten times faster than on the I-bus. This is because the power train systems require information with as short a delay as possible.
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.
| The MIU uses the following information: |
| Information | Values | From | Value dependent on the following sensor input, signal or function |
|
LH direction indicators
|
ON/OFF
|
DICE
|
MIU turns on the indicator lamp for the LH direction indicators.
|
|
RH direction indicators
|
ON/OFF
|
DICE
|
MIU turns on the indicator lamp for the RH direction indicators.
|
|
Rear fog light
|
ON/OFF
|
DICE
|
MIU turns on the indicator lamp for the rear fog lights.
|
|
Driver's door
|
OPEN/CLOSED
|
TWICE
|
Door switch. MIU turns on the driver's door symbol.
|
|
Passenger door
|
OPEN/CLOSED
|
TWICE
|
Door switch. MIU turns on the passenger door symbol.
|
|
LH rear door
|
OPEN/CLOSED
|
TWICE
|
Door switch. MIU turns on the rear left door symbol.
|
|
RH rear door
|
OPEN/CLOSED
|
TWICE
|
Door switch. MIU turns on the rear right door symbol.
|
|
Boot lid/tailgate
|
OPEN/CLOSED
|
TWICE
|
Lid switch. MIU turns on boot lid/tailgate symbol.
|
|
Steering wheel location
|
LHD/RHD
|
TWICE
|
MIU turns on the indicator for the driver/passenger door
|
|
Info Disp Lamp
|
ON/OFF
|
SID
|
In the event of a text message, the MIU turns on the Info Display light.
|
|
Rheostat level
|
0-100 %
|
SID
|
Rheostat control module input. Main instrument unit controls instrument lighting.
|
|
Rheostat Night Panel
|
0-100 %
|
SID
|
Rheostat control module input internally reduced by a fixed value.
|
|
Night Panel
|
ON/OFF
|
SID
|
Button. MIU turns off certain instruments and display illumination.
|
|
Display lighting
|
0-100 %
|
SID
|
Rheostat control module input. MIU uses the information to control the display illumination.
|
|
Light intensity in compartment
|
Lux
|
SID
|
Light sensor. MIU uses the value to control the brightness of the indicator lamps.
|
|
CHECK ENGINE lamp
|
ON/OFF
|
EDC 15, PSG 16
|
Internal diagnosis. MIU turns on CHECK ENGINE lamp.
|
|
CRUISE Lamp
|
ON/OFF
|
EDC 15, PSG 16
|
Cruise control function. MIU turns on the CRUISE lamp.
|
|
Fuel consumed since start
|
0-65535 ml
|
EDC 15, PSG 16
|
Fuel injection function. Used by SID for the trip computer function, can be adjusted with offset in MIU.
|
|
Engine speed
|
0-6000 rpm
|
EDC 15, PSG 16
|
Crankshaft position sensor. MIU control the tachometer.
|
|
Coolant temperature
|
-40-215ºC
|
EDC 15, PSG 16
|
Coolant sensor. MIU controls the coolant temperature gauge.
|
|
Glow indicator lamp
|
ON/OFF
|
EDC 15, PSG 16
|
Glow function. Glow indicator lamp comes on while glow function active.
|
| The MIU sends the following information: |
| Information | Values | Used by | Value dependent on the following sensor input, signal or function |
|
Vehicle speed
|
km/h (mph)
|
EDC 15, PSG 16, DICE, SID, ACC, Audio, TWICE, STC
|
The main instrument unit calculates the current vehicle speed based on information on the wheel speed from the ABS control module.
|
|
Sound
|
Sound information
|
SID
|
Request for acoustical signal when central warning lamp or Info Displ goes on.
|
|
Fuel level
|
litres
|
SID
|
MIU sends information on the current fuel volume in the tank.
|
|
Odometer reading
|
km, miles
|
SID
|
Information on the driven distance.
|
|
Identification number
|
---
|
TWICE
|
Immobilizer function
|
|
Fuel consumed since start
|
0-65535 ml
|
SID
|
Bus from engine control module. The value is corrected by an adjustment factor in the MIU. The factor can be adjusted with the diagnostic tool.
|
|
STOP FOR FUEL
|
ON/OFF
|
SID
|
When the fuel level drops below 5 litres, ON is sent. MIU sends a text message to SID, which displays the message.
|
|
Diagnostics communication
|
---
|
DICE/
Diagnostic tool |
DICE/diagnostic tool.
|
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