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Bus communication

Bus communication

System overview

For a detailed description of the car's bus systems, see ”Bus and diagnostic communication" System overview .

Diagnostics

In a bus system, it is necessary for all the units to be able to communicate with each other. For example, the engine cannot be started unless Trionic T7 can receive immobilizer information transmitted by TWICE.

Permanent bus faults

All communications between the diagnostic tool and systems on the bus take place via DICE. Irrespective of which system is being contacted, the diagnostic tool, with the help of DICE, will make sure that all the systems on the bus are active and communicating. The diagnostic tool will indicate any control modules missing from the bus. This means that all the control modules are communicating correctly on the bus unless the diagnostic tool warns otherwise.

Intermittent bus faults

Trionic continuously checks to see that TCM and MIU are communicating correctly. Diagnostic trouble codes will be generated if an intermittent fault should occur in the bus communication. The cause of the fault could be that the power supply or one of the bus leads to a control module is missing

Missing control module Diagnostic trouble code
TCM

P1623

MIU

P1622

TC/ABS

P1625



Bus messages

Trionic T7 uses the following information:

Information Unit Sensor system Description
Maximum permissible torque

Nm

TCM

TCM sends maximum permissible torque, unit Nm. The value is used in the air mass control for engine torque limitation.

Sport position selected

ON/OFF

TCM

TCM sends sport position, unit ON/OFF. The value is used in the air mass control to correct the conversion of the pedal position to requested air mass/combustion.

Selector lever position, automatic transmission

PRND321

TCM

TCM sends selector lever position, unit PRND321. The value is used in the air mass control for idle speed control.

Vehicle speed, rear left wheel

km/h

MIU

MIU sends speed, unit km/h. The value is used by cruise control and as a substitute value if the speed signal from ABS disappears.

Reverse gear selected

ON/OFF

DICE

DICE sends reverse gear engaged, unit ON/OFF. The value is used to determine if first gear or reverse gear is engaged as the gear ratio is not enough to distinguish between them.

A/C request

ON/OFF

DICE

DICE sends A/C request, unit ON/OFF. The value is used in the air mass control, compensation, to compensate for the increase in load. The control module also activates the A/C relay.

A/C pressure, high-pressure side

bar

DICE

DICE sends pressure, unit bar. The value is used in the air mass control, compensation, to calculate the increase in load before the A/C compressor is activated.

Current consumption

A

DICE

DICE sends the calculated current consumption of the electrically heated rear window and radiator fans just before they are activated, unit A. The value is used in the air mass control, compensation, to compensate for the increase in load.

Fuel level

Litres

MIU

MIU sends fuel level, unit Litres. The value is used in the on-board diagnostics to generate special diagnostic trouble codes during misfiring in conjunction with low fuel levels and for adaptation of the tank pressure sensor value.

CHECK ENGINE Request

ON/OFF

TCM

TCM sends request, unit ON/OFF. The value is used in the on-board diagnostics to turn on the CHECK ENGINE lamp when ON is sent. Diagnostic trouble code P1624 is generated to indicate a fault in TCM.

Immobilizer

ON/OFF

TWICE

TWICE sends immobilizer, unit ON/OFF. The value is used in the fuel injection to activate fuel shut-off.

Ignition +50

ON/OFF

DICE

DICE sends +50, unit ON/OFF. The value is used for diagnosis of the crankshaft position sensor.

Diagnostics



DICE/ diagnostic tool

The diagnostic tool sends a diagnostics request via DICE, no unit. The value is used to respond to the current request.



Trionic T7 transmits the following information:

Information Unit User system Description
Engine Torque

Nm

TCM

Current air mass/combustion converted to engine torque, unit Nm. The value is used by TCM.

Accelerator pedal position

%

TCM

The highest of the air mass/combustion values requested from the accelerator pedal position or cruise control is selected. The value is converted to a corresponding accelerator pedal position, unit percent. The value is used by TCM.

Kick Down

ON/OFF

TCM

When the voltage from pedal potentiometer 1 corresponds with the kickdown position (below 1.50 V), kickdown ON, unit ON/OFF is sent. The value is used by TCM.

Engine RPM

rpm

MIU, TCM and ACC

Current engine speed sent, unit rpm. The value is used by TCM, ACC and MIU.

Engine coolant temperature (C)

°C

MIU, DICE and ACC

Current temperature is sent, unit °C. The value is used by ACC, MIU and DICE.

Engine running.

ON/OFF

ACC, DICE

ON is sent when the engine speed exceeds 650 rpm, unit ON/OFF. The value is used by ACC and DICE.

Turbo pressure gauge value

No units (0-255)

MIU

Current air mass/combustion is converted to a value between 0 and 255. The value is used by MIU. A fixed value corresponding with a needle position between white and orange is sent when the engine is stationary.

CHECK ENGINE.

ON/OFF

MIU

ON, unit ON/OFF, is sent when the on-board diagnostics reports that the lamp is to be turned on. The value is used by MIU.

SHIFT UP

(Only US/CA)

ON/OFF

MIU

ON, unit ON/OFF, is sent at low loads and high engine speeds and at very high engine speeds irrespective of load. The value is used by MIU.

CRUISE lamp

ON/OFF

MIU

ON, unit ON/OFF, is sent when cruise control is activated with the switch. The value is used by MIU.

Fuel consumed since start

ml

MIU

When the ignition is switched on, the value is 0 ml and is then accumulated for each injection, unit ml. The value is used by MIU.

Diagnostics



DICE/ diagnostic tool

Trionic T7 responds to the diagnostics request from the diagnostic tool via DICE, no unit.