reset BMW 540i 1999 E39 M62TU Engine Workshop Manual

29
AUXILIARY FAN CONTROL
The Auxiliary Fan motor incorporates an out-
put final stage that activates the fan motor at
variable speeds.
The auxiliary fan is controlled by ME 7.2. The
motor output stage receives power and
ground and activates the motor based on a
PWM signal (10 - 100 Hz) received from the
ME 7.2.
Similar to the aux fan in the E46 with MS 42.0
control, the fan is activated based on the fol-
lowing factors:
• Radiator outlet temperature sensor input exceeds a preset temperature.
• IHKA signalling via the K and CAN bus based on calculated refrigerant pressures.
• Vehicle speed
• Battery voltage level
When the over temperature light in the instrument cluster is on (120
OC) the fan is run in the
overrun function. This signal is provided to the DME via the CAN bus. When this occurs
the fan is run at a frequency of 10 Hz.
FAN MOTOR MODULE
POWER, GROUND & SIGNAL WIRES