Bus communication
| Bus communication |
| System overview |
For a detailed description of the car's bus system, see “Bus and diagnostic communication”, System overview .
| Diagnostics |
In a bus system, all units must be able to communicate with each other. For example, the engine cannot be started unless the Trionic T7 can receive the immobilization information sent out by TWICE.
Permanent bus faults
All communication between the diagnostic tool and systems connected to the bus takes place through DICE. Irrespective of which system is contacted, the diagnostic tool first checks by means of DICE that all on-board systems connected to the bus are turned on and in communication. If any control module connected to the bus is missing, the diagnostic tool will show this. This means that all control modules connected to the bus can communicate properly unless the diagnostic tool warns otherwise.Intermittent bus faults
Trionic continually checks that the TCM, MIU and TC/ABS communicate correctly. If intermittent faults on the bus communication occur, fault codes will be generated. The cause of the fault can be that the control module in question has lost its power supply or one of the bus lines.| Missing control module | DTC |
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TCM
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P1923
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MIU
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P1908
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TC/ABS
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P1925
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| The Trionic T7 uses the following information: |
| Information | Sensor system | Description |
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Maximum permitted torque (Nm)
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TCM
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The TCM sends maximum permitted torque, unit Nm. The value is used in the air mass control system for torque limitation.
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Sports mode selected (ON/OFF)
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TCM
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The TCM sends sports mode, unit ON/OFF. The value is used in the air mass control to correct the pedal position conversion to the requested air mass/combustion.
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Selector lever position, automatic gearbox (PRND321)
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TCM
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The TCM sends selector lever position, unit PRND321. The value is used in the air mass control for idle speed control.
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Vehicle speed, left rear wheel (km/h)
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MIU
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MIU sends speed, unit km/h. The value is used by the cruise control and as a substitute if the speed signal from ABS or TC/ABS disappears.
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Reverse gear selected (ON/OFF)
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DICE
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DICE sends reverse gear selected, unit ON/OFF. The value is used to determine whether first gear or reverse is engaged as the gear ratio does not adequately distinguish between these gears.
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A/C request (ON/OFF)
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DICE
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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.
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A/C pressure, high pressure side (bar)
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DICE
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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.
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Current consumption (A)
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DICE
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DICE sends calculated current consumption of the electrically heated rear window and radiator fan immediately before they are activated, unit A. The value is used in the air mass control, compensation, to compensate for the load increase.
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Fast idling speed (ON/OFF)
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DICE
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DICE sends fast idling speed, unit ON/OFF. ON is sent if the radiator fan is activated for high-speed during the present driving cycle. The value is used in the idling speed control.
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Brake lights (ON/OFF)
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TWICE
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TWICE sends brake lights, unit ON/OFF. The value is used in the air mass control for engine torque limitation.
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Fuel level (Litres)
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MIU
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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.
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CHECK ENGINE Request (ON/OFF)
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TCM
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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.
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Immobilizer (ON/OFF)
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TWICE
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TWICE sends immobilizer, unit ON/OFF. The value is used in the fuel injection system to activate fuel shut-off.
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Ignition +50 circuit (ON/OFF)
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DICE
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DICE sends out +50, unit ON/OFF. The value is used for diagnosis of the crankshaft position sensor.
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Vehicle speed, right front wheel
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TC/ABS
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The signal comes from the wheel speed sensor FR. The value is used for Traction Control.
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Vehicle speed, output rpm
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TCM
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Engine speed signal converted to vehicle speed.
The engine speed signal comes from a sensor on the gearbox. Output rpm is the same as the vehicle speed. The value is used for torque limitation. |
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Diagnostics
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DICE/diagnostic tool
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The diagnostic tool sends diagnostic request via DICE, unit missing. The value is used to respond to the request concerned.
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| The Trionic T7 sends out the following information: |
| Information | User System | |
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Engine torque (Nm)
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TCM
TC/ABS |
Current air mass/combustion converted to torque, unit Nm. The value is used by TCM and TC/ABS.
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Accelerator pedal position (%)
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TCM
TC/ABS |
Highest requested value of air mass/combustion from the accelerator position or cruise control is selected. The value is converted to a corresponding accelerator position, unit percent. The value is used by TCM and TC/ABS.
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Kickdown (ON/OFF)
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TCM
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When the voltage from pedal potentiometer 1 corresponds to the kickdown position (less than 1.50 V), kickdown ON, unit ON/OFF, is sent. The value is used by the TCM.
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Engine speed (rpm )
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MIU, TCM, ACC and TC/ABS
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Current engine speed is sent, unit rpm. The value is used by TCM, ACC, MIU and TC/ABS.
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Coolant temperature (°C)
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MIU, DICE and ACC
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The current temperature is sent, unit °C. The value is used by ACC, MIU and DICE.
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Engine running (ON/OFF)
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ACC, DICE
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ON is sent, unit ON/OFF, when engine speed exceeds 650 rpm. The value is used by the ACC and DICE.
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CHECK ENGINE (ON/OFF)
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MIU
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ON, unit ON/OFF, is sent when On-board diagnostics reports that the lamp should be lit. The value is used by the MIU.
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SHIFT UP (ON/OFF)
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MIU
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ON, unit ON/OFF, is sent when running with a light load and high rpm, and at very high rpm irrespective of load. The value is used by the MIU.
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CRUISE lamp (ON/OFF)
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MIU
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ON, unit ON/OFF, is sent when cruise control is activated with the switch. The value is used by the MIU.
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Fuel used since start (ml)
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MIU
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The value is 0 ml when the ignition is switched on and is then incremented for each injection, unit ml. The value is used by the MIU.
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Diagnostics
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DICE/diagnostic tool
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The Trionic T7 answers the diagnosis request from the diagnostic tool via DICE, unit missing.
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