Bus communication
| Bus communication |
| • |
Control module, ACC (216)
|
|
| • |
Radio connector C (267c)
|
|
| • |
Control module, airbag/SRS (331)
|
|
| • |
Radio (353)
|
|
| • |
CD changer (355)
|
|
| • |
Control module PSM (357Dk)
|
|
| • |
Control module, Trionic T7 (430b)
|
|
| • |
MIU (540d)
|
|
| • |
SID (541)
|
|
| • |
Control module (ABS) 547
|
|
| • |
Control module STC (565)
|
|
| • |
Control module, Trionic T7 OBDII (589b)
|
|
| • |
Control module, DICE (628)
|
|
| • |
Control module, TWICE (632)
|
|
| Bus communication, other petrol-engine variants |
| • |
Control module, ACC (216)
|
|
| • |
Radio connector C (267c)
|
|
| • |
Control module, airbag/SRS (331)
|
|
| • |
Radio (353)
|
|
| • |
CD changer (355)
|
|
| • |
Control module PSM (357Dk)
|
|
| • |
Control module, Trionic T5 (430a)
|
|
| • |
Control module, TCM (502)
|
|
| • |
Control module M2.10.3 (505)
|
|
| • |
MIU (540b)
|
|
| • |
SID (541)
|
|
| • |
Control module (ABS) 547
|
|
| • |
Control module STC (565)
|
|
| • |
Control module, Trionic T5 OBDII (589a)
|
|
| • |
Control module, DICE (628)
|
|
| • |
Control module, TWICE (632)
|
|
| Bus communication, diesel |
| • |
Control module, ACC (216)
|
|
| • |
Radio connector C (267c)
|
|
| • |
Control module, airbag/SRS (331)
|
|
| • |
Radio (353)
|
|
| • |
CD changer (355)
|
|
| • |
Control module PSM (357Dk)
|
|
| • |
MIU (540c)
|
|
| • |
SID (541)
|
|
| • |
Control module (ABS) 547
|
|
| • |
Control module STC (565)
|
|
| • |
Control module, EDC 15 (595)
|
|
| • |
Control module, auxiliary heater (597)
|
|
| • |
Diesel pump (598)
|
|
| • |
Control module, DICE (628)
|
|
| • |
Control module, TWICE (632)
|
|
| P-bus and I-bus |
A bus is a number of wires on which information is sent digitally and serially. Digital means that the voltage difference between two wires has only two values, about 0V or 5V. The information is coded so that different combinations of pulses with values 0V and 5V have different meanings.
Serial means that the information is sent in ”packets” one after the other in rapid succession.
The bus is divided into the P-bus (Powertrain Bus) and the I-bus (Instrument Bus). Both buses are connected to the main instrument unit (MIU). The buses are electrically isolated from each other.
Only diesel-engined cars and cars with Trionic T7 have a P-bus. Other petrol-engined variants have the same engine management system and automatic transmission as the earlier 900 model (T5, M2.10.3 and TCM) and these have no bus connections.
As in the 9-5, the Airbag and ABS control modules have no bus connections.
The diagnostics instrument is not directly connected to the bus but communicates via DICE, which is connected to the I-bus, and therefore has access to all the 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 the other control modules on the bus. The MIU is responsible for making information on one bus available to 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 transmitted by the control module whenever the information changes.
Transmission of information between control modules occurs on two leads, bus+ (green lead) and bus- (white lead). The leads are twisted to increase tolerance to electrical interference.
| DICE uses the following information |
|
Information
|
Values
|
Off
|
The value depends on the following sensor input, signal or function
|
|
LH rear lights
|
ON/OFF
|
TWICE
|
Control module input supplied with current from lights switch
DICE uses the information for the instrument lighting, acoustic warning and rear fog lights. |
|
RH rear lights
|
ON/OFF
|
TWICE
|
Control module input supplied with current from lights switch
DICE uses the information for the instrument lighting, acoustic warning and rear fog lights. |
|
Driver's door
|
OPEN/CLOSED
|
TWICE
|
Door switch
DICE uses the information to turn the interior lighting on or off, for the visual warning and for the “Follow me home” function. |
|
Passenger door
|
OPEN/CLOSED
|
TWICE
|
Door switch
DICE uses the information to turn the interior lighting on or off, for the visual warning and for the “Follow me home” function. |
|
Rear door, Left
|
OPEN/CLOSED
|
TWICE
|
Door switch
DICE uses the information to turn on/off the interior lighting. |
|
Rear door, Right
|
OPEN/CLOSED
|
TWICE
|
Door switch
DICE uses the information to turn on/off the interior lighting. |
|
Boot lid
|
OPEN/CLOSED
|
TWICE
|
Lid switch
DICE uses the information to turn on/off the luggage compartment lighting. |
|
Hazard flashers
|
ON/OFF
|
TWICE
|
Anti-theft alarm function and central locking system function
DICE uses the information to activate/deactivate the hazard flashers for the car's anti-theft alarm. |
|
Central locking system
|
UNLOCKED/LOCKED
|
TWICE
|
Central locking system function
DICE uses the information to turn off/on the interior lighting. |
|
A/C
|
ON/OFF
|
ACC
|
AUTO selected and outside temperature (bus from SID)
DICE uses the information to activate/deactivate the car's radiator fan and A/C systems. |
|
Rear Window Heater
|
ON/OFF
|
ACC
|
Button on dashboard
DICE uses the information to activate/deactivate the electrical heating. |
|
Vehicle speed
|
km/h, mph
|
MIU
|
Rear left wheel speed (lead from ABS)
DICE uses the information for the intermittent windscreen wiper operation and for controlling the car's radiator fan and A/C systems. |
|
A/C Relay
|
ON/OFF
|
MIU
|
Lead from T5 or Motronic.
DICE uses the information to activate/deactivate the car's radiator fan and A/C systems. |
|
Rheostat level
|
0-100 %
|
SID
|
Rheostat control module input
DICE uses the information to control the brightness of the instrument and control lighting. |
|
Rheostat Night Panel
|
0-100 %
|
SID
|
Rheostat control module input reduced internally by a fixed value
DICE uses the information to control the brightness of the buttons when NIGHT PANEL is active. |
|
Night Panel
|
ON/OFF
|
SID
|
Button
DICE uses the information on whether NIGHT PANEL is activated or deactivated. |
|
Outside temperature
|
°C
|
SID
|
Outside temperature sensor, control module adjustment
DICE uses the information to control the car's radiator fan and A/C systems. |
|
Engine Running
|
ON/OFF
|
EDC 15,
T7 |
Crankshaft position sensor
DICE uses the information to control the car's radiator fan and A/C systems. |
|
Coolant temperature
|
-50 - 200°C
|
EDC 15,
T7 |
Coolant temperature sensor
DICE uses the information to control the radiator fan and A/C systems. |
|
Diagnostics
|
|
Tech 2
|
Control module should be live and the bus leads intact.
See Bus and diagnostics communication 
|
| DICE sends the following information |
|
Information
|
Values
|
Used by
|
The value depends on the following sensor input, signal or function
|
|
A/C
|
ON/OFF
|
MIU (Cars with B204) EDC 15 (Cars with D223) T7 (Cars with B205, B235)
|
A/C (bus from ACC), coolant temperature (bus from T7/EDC 15/MIU), A/C pressure and evaporator temperature.
Trionic and EDC 15 use the information to control relays. |
|
A/C Pressure
|
bar
|
EDC 15 (Cars with D223) T7(Cars with B205, B235)
|
A/C pressure sensor
EDC 15/T7 uses the information for load compensation. |
|
Current consumption
|
A
|
MIU (Cars with B204) T7(Cars with B205, B235)
|
Control module activation of the relay outputs for the radiator fans and the electrically heated rear window
Trionic uses the information for load compensation. |
|
Position lights
|
ON/OFF
|
SID
|
Control module activation of the relay output for the headlamp relay
SID uses the information for the instrument lighting functions. |
|
Electrically heated rear window
|
ON/OFF
|
ACC
|
Control module activation of the relay output for the electrically heated rear window
ACC uses the information to confirm that the rear window heating is active. |
|
Rear fog light defective
|
YES/NO
|
SID
|
Control module current measurement of output to lamp
SID uses the information to display a CHECK message. |
|
Left Direction Indicator
|
ON/OFF
|
MIU,
SID |
Control module activation of output to lamps
MIU uses the information to indicate activated LH direction indicators with the indicator lamp on the main instrument unit SID uses the information for acoustic indication of activated direction indicators “tick-tack”. |
|
Right Direction Indicator
|
ON/OFF
|
MIU,
SID |
Control module activation of output to lamps
MIU uses the information to indicate activated RH direction indicators with the indicator lamp on the main instrument unit. SID uses the information for acoustic indication of activated direction indicators “tick-tack”. |
|
Rear Fog Light
|
ON/OFF
|
MIU
|
Control module activation of output to fog light
MIU uses the information to turn on/off the rear fog light indicator on the main instrument unit. |
|
Sound
|
Acoustic information
|
SID
|
Control module programming and seat-belt buckle switches, driver's door or passenger's door open (bus from TWICE)
SID uses the information to generate acoustic warnings. |
|
Ignition +B
|
ON/OFF
|
Audio, TWICE
|
Ignition switch
Informs Audio and TWICE of the position of the ignition switch. |
|
Ignition +15
|
ON/OFF
|
-
|
Ignition switch
Informs TWICE of the position of the ignition switch. |
|
Ignition +54
|
ON/OFF
|
TWICE
|
Ignition switch
Informs TWICE of the position of the ignition switch. |
|
Ignition +50
|
ON/OFF
|
TWICE, ACC, T7 (Cars with B205, B235)
|
+15 present but not +54
Informs TWICE and ACC of the position of the ignition switch. |
|
Idling speed increase
|
ON/OFF
|
T7
|
Radiator fan High has been activated once during the trip.
|
|
Reverse gear
|
ON/OFF
|
T7
|
Reversing lights switch
|
|
Diagnostics
|
|
Tech 2
|
Control module should be live and the bus leads intact.
See Bus and diagnostics communication
|
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