Bus messages, TCM

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Bus messages, TCM

For further information on the bus, see System overview, bus and diagnostics communication, petrol

The TCM uses the following information:

Information	Unit	From	Description
Engine torque	Nm	Engine management system	The current air mass/combustion is converted into torque and given in Nm
Pedal position	%	Engine management system	The engine control module uses the highest requested values for air mass/combustion either from the pedal position or from the cruise control. The value is converted to a corresponding pedal position, unit %.
Kickdown	ON/OFF	Engine management system	When the voltage from pedal potentiometer 1 corresponds to the kickdown position (below 1.50 V), Kickdown ON will be sent.
Engine speed	rpm	Engine management system	Current engine speed, unit rpm. Additionally, the value is used to compare engine speed with the speed of the input shaft when Lock-up is activated.
Brake lights	ON/OFF	TWICE	Brake lights, unit ON/OFF.
ENGINE JERK	ON/OFF	Engine management system	If engine surge has been detected by the engine management system a message is sent out on the bus and is used by TCM which then adapts the shifting points to avoid engine surge.
Reduced engine power	ON/OFF	Engine management system	Driving at high altitude (approx. 2,400 metres above sea level, pressure approx. 80 kPa) results in reduced engine power. TCM then uses a special shifting program which means that the engine is allowed to run at a higher rpm than normal.

The TCM sends the following information:

Information	Values	Used by	Description
Maximum permissible torque	Nm	Engine management system	The TCM sends the maximum permissible torque, unit Nm. The value is used in the mass air flow control circuit for torque limitation.
SPORT	ON/OFF	Engine management system, MIU	The TCM sends the sport position, unit ON/OFF. The value is used in the mass air flow control circuit to correct the pedal position's conversion into the requested air mass/combustion. The MIU causes the SPORT indicator lamp to light up.
Selector lever position	P, R, N, D, M, L Diesel: P, R, N, D, 3, 4, L	Engine management system, MIU	TCM sends the selector lever position, unit P, R, N, D, M, and L. diesel: P, R, N, D, 3, 4, and L. The value uses the engine management system in the air mass control for idle speed control. MIU uses the value to light the appropriate segment in the selector lever display.
CHECK GEARBOX lamp	ON/OFF	MIU	ON is sent when on-board diagnostics reports that the lamp should be lit, unit ON/OFF. The value is used by MIU.
Text message TRANSMISSION OVERHEATING	Text message	SID	When the oil temperature in the transmission exceeds 155°C the information TRANSMISSION OVERHEATING is sent, unit ON/OFF. The SID unit will display this message.
Selected gear position	1 - 5	MIU	TCM sends out the message "Selected gear". This is used by MIU to display the current gear in position M.