Porsche 944 - Manual (Page 140)

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Fuel System - Electronic Control 944 S/944 S2
This DME 944 S Diagnosing/Troubleshooting Plan is based on the contents of the fault
memory.
Paths not included in self-diagnosis can be diagnosed with conventional equipment (Test
Points 17-25. see Fault List).
Troubleshooting requires that the person performing the tests
is familiar with the location of components, the function and technical interconnections of the
systems being tested (model information).
can read and evaluate Porsche wiring diagrams.
knows the functions of circuits and relays, and
is capable of using testers, such as the oscilloscpe, voltmeter, ohmmeter and ammeter, as
well as evaluating the test results.
Important!
A fault text in the display (Fault List and Flashing Code) does not always indicate a fault in the
pertinent component, but could also concern the corresponding control unit or connecting leads
(paths) between the component and control unit.
Troubleshooting on a running engine in the form of disconnection of plugs, etc. must not be
carried out prior to reading the fault memory, since such action could be stored as faults in the
fault memory.
9288 System Tester Information
Displayed in Tester
Fault does not exist, this could mean:
Fault not existing at time of testing (loose contact).
Remedy: visual inspection of path (connection).
Conditions, with which the fault is tested. ara not the same as the conditions, with which the
fault had occurred.
Remedy: conform with conditions displayed in the tester.
Signal Not Plausible:
Signal of the monitored component does not fit in the tolerance range of the value calculated in
the control unit.
D 24/28 - 6 DME - Diagnosing/Troubleshooting
Printed In Germany - XXI, 1989