Porsche 944 - Manual (Page 152)

24/28
Fuel System - Electronic Control 944 S/944 S2
Fault, Fault Code Possible Causes, Elimination, Remarks
Test Point
12:
Control
unit
(knock
computer)
Fault Code
1_33
Ignition timing is retarded 6° in case of this fault.
Replace control unit.
Test Point
13:
Hall signal
Fault Code
1_34
Disconnect plug on cylinder head behind the camshaft drive gear and connect a
three-pin adapter lead (VW 1501) inbetween to check the Hall signal. Connect
oscilloscope positive and negative test leads on terminals 1 and 2 of the adapter
lead. Start the engine.
This signal should be displayed when the Hall system is okay:
Ignition timing will be retarded approximately 6° in all speed ranges, if the DME
control unit recognizes that the Hall signal is missing.
Protective circuit test:
Turn off ignition. Disconnect Hall plug. Start the engine. Idle speed ignition timing
will adjust itself to approximately 4° before TDC (944 S). There must be a certain
load signal from the air flow sensor in case of 944 S2 cars.
Test Point
14:
Control
unit faulty
Fault Code
1_41
Replace control unit.
D 24/28 - 18 DME - Diagnosing/Troubleshooting
Printed In Germany - XXI, 1989