Porsche 928 Workshop Manual page 382

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928 LH-Jetronic 24
Oscilloscope should display following control
signal.
ir-
U
If no signal is displayed, check power flow
from terminal 16 of electronic ignition
control unit plug to terminal 1 of LH control
unit plug.
If power flow is okay. replace electronic
ignition control unit.
TEST POINT 3
LH Air Flow Sensor
1. Take off upper air cleaner housing and
filter element.
1 23456
Pull off relay XVI for this purpose and
bridge terminals 30 and 87.
Specification: battery voltage.
4. Measure resistance for idle mixture
position.
Connect ohmmeter on terminals 6 and 3
of air flow sensor.
Specification: 0 1000 ohms.
5. Connect ohmmeter on terminals 5 and 3
of air flow sensor.
Specification: 3.6 4.1 ohms.
2. Pull lower air cleaner housing and air
flow sensor out of air guide housing.
3. Pull off multiple pin plug on air flow
sensor.
Measure voltage between terminals 4 and 2
(positive) on disconnected plug.
Printed inGermany VIII, 1984
Troubleshooting LH-Jetronic 24.113