Porsche 928 Workshop Manual page 616

928 S4
928 GT Fuel System I Electronic Control
28
Fault, Fautt Code Possible Causes, Elimination, Remarks
Test point 8
Knock sensor II
Fault code 2-32
Knock sensor II: sensor signal not plausible. Check:
- Knock sensor mounting (note tightening torque
and type of screw)
-
Wiring and plug connections according to wiring diagram
Reconnect the sensors to eliminate contact resistance.
-
Is any coolant or other fluid present at the knock sensors?
- Renew knock sensor
If the knock sensor is faulty, the ignition will be retarded (safety cir-
cuit).
Test point 9
Control unit (knock sensor)
Fault code 2-33
This fault causes the ignition to be retarded by 6".
Renew the control unit,
Test point IO
Hall signal
Fault code 2-34
To check the Hall signal, disconnect the plug connections at cylinder
head 1-4 behind the camshaft drive gear, and insert a 3.pole adapter
lead (VW 1501) into the signal lead. Connect oscilloscope + and
test leads to terminals 1 and 2 of the adapter lead. Stan the engine.
If the Hall transmitter is in good working order, the following signal
must appear on the screen:
Voltage signal ca. 5 V
If the EZK control unit identifies the absence of the Hall signal, the ig-
nition is retarded.
EZK-DiagnosisiTroubleshooting
Printed in
Germany - Xxv, 1990
D28-9