OBD port BMW 540i 2000 E39 M62TU Engine Workshop Manual

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RADIATOR OUTLET TEMP SENSOR
First seen on the MS 42.0 control system, the ME
7.2 uses an additional water temperature sensor
located on the radiator outlet.
ME 7.2 requires this signal to monitor the water
temperature leaving the radiator for precise acti-
vation of the IHKA auxiliary fan.
DSC III - ROAD SPEED SIGNAL
ME 7.2 receives the road speed signal directly
from the DSC III control module for maximum
vehicle speed management. The DSC control
module provides a processed output of the right
rear wheel speed sensor as a digital square wave
signal. The frequency of the signal is proportion-
al to the speed of the vehicle (48 pulses per one
revolution of the wheel).
The cruise control function (FGR) of the ME 7.2 also monitors vehicle speed from the redun-
dant vehicle speed CAN bus signal. The CAN bus speed signal is provided by the DSC III
control module and based on the combined average of both front wheel speed signals.
Additionally, ME 7.2 monitors all four wheel speed signals via CAN bus signalling to detect
abrupt fluctuations in vehicle speed signals for the purpose of detecting rough road sur-
faces. This is continuously monitored as part of the OBD II emission requirements provid-
ing a correction factor for misfire detection plausibility. Earlier systems only monitored the
right rear speed signal input from DSC.