Circuit description
The
fan
speed sensor is a Hall effect sensor and when
the fan rotates the sensor receives impulses (6 pulses/
rev).
The output signal from the fan speed sensor, pin E on
sensor connector to pin A35 on the engine ECU, is a
voltage signal which is proportional to the fan speed.
Pin A7 on the engine ECU provides pin A at the sensor
connector with an operating voltage of +5 V. Pin D at
the sensor connector is connected to battery negative
via pin A39 on the engine ECU.
The fan clutch engagement is controlled by engine
ECU. The clutch solenoid is energized with a PWM
signal by the engine ECU pin B49.
Sensor Engine ECU Signal type
E A35 square wave (sensor out-
put)
D A39 bat- (sensor supply -)
B - bat+
C B49 PWM (low side switch)
A A7 +5V (sensor supply +)
P0018089
30-2 Fault Tracing
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