SHOP MANUAL
Ch 6 page 68
ELECTRICAL SYSTEM
Request for torque
The control units for the gearbox management system, TCU, and VCU, can, if necessary, request torque via
the engine control unit, e.g. when changing gear and for traction control. The system concerned may request
maximum torque for a short period, then the torque is limited to approximately 70% for a further period. If the
time limit is exceeded, the engine control unit resumes control.
If both systems request control over torque at the same time, the TCU request has the highest priority.
Request for limited torque
The control units for the gearbox management system, TCU, and VCU, can, if necessary, request limited
torque. The engine control unit then limits the fuel volume according to the system which requests the lowest
torque. If required, the fuel injection can be switched off completely. The function is not accessible under start.
If the torque is limited so much when idling that there is a risk of the engine stopping, the idle speed control will
intervene and increase the fuel volume so that the engine speed is maintained.
Request for control of AC compressor
The AC compressor coupling coil is controlled by a signal from the VCU2 unit when using ACC.
Request for engine shutdown
The VCU can send a signal to the engine control unit to switch off the engine. The engine control unit then car-
ries out a controlled shutdown.
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