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944 Maintenance, Self-diagnosis
03
Testing the power supply of the air-flow
sensor:
Ignition on
On the extracted plug of the air-flow sensor, a
voltage of 5 V +- 0,5 V must be measurable
between terminal 3 (positive) and terminal 4
(negative) (if necessary, check by reference
to the circuit diagram).
33
Testing the air-flow sensor
From the extracted plug of the air-flow
sensor,
link plug terminal 3 to air-flow sensor plug ter-
minal 3 and plug terminal 4 to air-flow sensor
plug terminal 4 using an auxiliary cable.
Measure the voltage between terminal 2 of
the air-flow sensor and ground.
Display:
approx. 250 - 260 mV
Detach the top of the air filter.
Using a non-metallic tool, slowly force the
airflow sensor valve to full load position.
A voltage rise must be observed during this
time.
Display:
approx. 0.2 V - ca. 4.6 V
No abrupt voltage changes must be
observed
during opening or closing. (Abrupt voltage
changes. i.e. the air-flow sensor is
defective).
Troubleshooting
Printed in Germany - XVI, 1987
03 - 23