Bus communication

Bus communication

•	Control module, ACC (216)

•	Radio connector C (267c)

•	Airbag/SRS control module (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)

•	Airbag/SRS control module (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)

•	Airbag/SRS control module (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” which are transmitted one after the other in rapid succession.

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.

Only diesel cars and Viggen have a P-bus. The other petrol engine variants have the same engine management system and automatic transmission as the 900 model (T5, M2.10.3 and TCM) that are not bus connected.

As in the 9-5, the Airbag and ABS control modules are not bus connected.

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 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.

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.

TWICE uses the following information

Information	Values	From	The value depends on the following sensor input, signal or function
Ignition +B	ON/OFF	DICE	Ignition switch. TWICE uses the information to notify the status of the ignition switch.
Ignition +15	ON/OFF	DICE	Ignition switch. TWICE uses the information to notify the status of the ignition switch.
Ignition +50	ON/OFF	DICE	+15 present but not +54 TWICE uses the information to notify the status of the ignition switch.
Ignition +54	ON/OFF	DICE	Ignition switch. TWICE uses the information to report the ignition switch status to the functions lamp check, seat belt warning, heated rear seat and electrically adjustable front seats.
Vehicle speed	km/h, mph	MIU	Rear left wheel speed (wire from ABS). TWICE uses the information for automatic control of the locks by the central locking system.
Identification number		MIU	Value created in MIU when immobilizer code is programmed in TWICE. TWICE uses the information for the immobilizer function.
SID Buttons	Night Panel	SID	Buttons. TWICE uses the information to disconnect the glass breakage sensor and tilt sensor. The “Night Panel” button is used for this when the key is removed from the ignition.
Outdoor temperature	°C	SID	Outside temperature sensor, control module adjustment. TWICE uses the information to control the rear seat heating.
Soft top position	Raised/ under movement/lowered	STC	Switches on top of windscreen frame, Soft top cover switch. TWICE sends information to automatically disconnect the glass breakage sensor when the top is down and to allow opening the luggage compartment.
Diagnostics communication		DICE/diagnostic tool	Control module should be powered and the bus leads intact See Bus and diagnostics communication

TWICE sends out the following information

Information	Values	Used by	The value depends on the following sensor input, signal or function
LH rear light broken	YES/NO	SID	Control module measurement of output current to lamps. SID uses the information to display a CHECK message.
RH rear light broken	YES/NO	SID	Control module measurement of output current to lamps. SID uses the information to display a CHECK message.
LH rear light	ON/OFF	DICE	Control module input supplied with current from light switch DICE uses the information to calculate the position of the light switch.
RH rear light	ON/OFF	DICE	Control module input supplied with current from light switch DICE uses the information to calculate the position of the light switch.
LH brake light broken	YES/NO	SID	Control module measurement of output current to lamp. SID uses the information to display a CHECK message.
RH brake light broken	YES/NO	SID	Control module measurement of output current to lamp. SID uses the information to display a CHECK message.
High-level brake light broken	YES/NO	SID	Control module measurement of output current to lamp. SID uses the information to display a CHECK message.
Brake lights	ON / OFF	SID	Brake light switch
Sound	Sound information	SID	In connection with text message. SID uses the information to generate sound for the seat belt warning function.
Driver's door	OPEN/CLOSED	MIU, PSM, DICE	Door switch. MIU uses the information to turn on the open door indicator. PSM uses the information to control the function for the electrically adjustable front seat. DICE uses the information to turn on the interior light.
Passenger door	OPEN/CLOSED	MIU, PSM, DICE	Door switch. MIU uses the information to turn on the open door indicator. PSM uses the information to control the function for the electrically adjustable front seat. DICE uses the information to turn on the interior light.
LH rear door	OPEN/CLOSED	MIU, DICE	Door switch. MIU uses the information to turn on the open door indicator. DICE uses the information to turn on the interior light.
RH rear door	OPEN/CLOSED	MIU, DICE	Door switch. MIU uses the information to turn on the open door indicator. DICE uses the information to turn on the interior light.
Boot lid	OPEN/CLOSED	MIU, DICE, STC	Lid switch. MIU uses the information to turn on the luggage compartment open indicator. DICE uses the information to turn on the luggage compartment light.
Test brake lights	ON/OFF	SID	Control module programming and brake light switch. SID informs the driver via a CHECK message to press the brake pedal.
Horn	0: 6: 42 ms	SID	Anti-theft alarm function and central locking system function. SID uses the information to activate the horn relay when the car is TSL locked.
Hazard flashers	ON/OFF	DICE	Anti-theft alarm function and central locking system function. DICE uses the information to activate the hazard flashers when the anti-theft alarm is tripped.
Text message		SID	Anti-theft alarm function and central locking system function. SID uses the information to display text messages for the TWICE functions.
Steering wheel location	LHD/RHD	ACC, MIU	Control module programming. ACC uses the information to detect the driver's zone. MIU uses the information to detect the driver's door.
Immobilizer	ON/OFF	MIU (Cars with B204)	Immobilizer function. MIU uses the information to allow the engine to start.
Key correct	ON/OFF	Audio	Immobilizer function. The audio system uses the information for theft security.
Central locking system	UNLOCKED/LOCKED	DICE	Central locking system function. DICE uses the information to turn on the interior light when the car is unlocked.
Diagnostics		DICE/diagnostic tool	Control module should be powered and the bus leads intact. See Bus and diagnostics communication