GF07.61-P-4012MOR ME Thermal Management, Function
GF07.61-P-4012MOR ME Thermal Management, Function
- refinement package
- as of model year 09
Function requirements for thermal management, general points
^ Circuit 87M ON (engine control ON)
^ Engine running
Thermal management, general points
The thermal management function of the ME-SFI [ME] control unit (N3/10) is used to regulate the engine coolant temperature by controlling the fan speed.
The fan and the fan speed are controlled according to the following sensors and signals:
- Coolant temperature sensor ()B11/4
- Oil sensor (oil level, temperature and grade) (B40), engine oil temperature
- AAC [KLA] control and operating unit (N22), air conditioning status via the interior CAN (CAN B) and engine compartment CAN (CAN C)
Thermal management function sequence
The ME-SFI [ME] control unit actuates the engine and air conditioning electric suction fan with integrated control (M4/7). The nominal fan speed is specified via a PWM signal by the ME-SFI [ME] control unit.
The duty cycle of the PWM signal is 10 to 90%.
Meaning:
10% Fan motor "OFF"
20% Fan motor "ON", minimal rpm
90% Fan motor "ON", maximum rpm
If actuation is faulty, the air fan rotates at the maximum rotational speed (fan emergency mode).
The AAC [KLA] control and operating unit sends the air conditioning status via the interior CAN and engine compartment CAN to the ME- SFI [ME] control unit.
If coolant temperature is too high, a warning message is displayed on the left multifunction display (A1p13) by the instrument cluster (A1). To do this the ME-SFI [ME] control unit sends an appropriate signal via the engine compartment CAN to the instrument cluster.
Delayed fan switch off
After "ignition OFF", the fan motor continues to run for up to 5 min. if the coolant temperature or engine oil temperature is above the specified maximum value.
The PWM signal duty cycle is 40 % maximum while the delayed fan switch-off is active.
If the battery voltage is dropping too much, the delayed fan switch-off is stopped.
