Porsche 928 Workshop Manual page 579

24128
Fuel System - Electronic Control
928 S4
928 GT
Equipment required for LH/EZK testing:
- Diagnostic tester 9288 (9268) with con-
necting leads
- 1 oscilloscope approved by Porsche
- 1 digital-display multimeter, internal re-
sistance at least 10 MQ
- 1 Bosch LJetronic test lead, Bosch No.
1684 463 093 (check lead for correct
polarity at plugs).
. 2 control-unit plug test leads (to be made
up in your own workshop) with two No.
17.457.2 tab connectors. to avoid damage
to the contacts in the control-unit plug
during testing.
- All sensor and ignition timing signals on
Porsche automobiles can be checked with
the engine testers recommended by
Porsche.
Since each tester manufacturer issues
different instructions for connection to the
vehicle, these instrucitons should always
be followed carefully to ensure correct
tester connection.
The following sensor signals can be
checked with the oscilloscope:
- Engine speed sensor signal I reference
mark signal
ti
signals
Idle speed control activation
2 adapter test leads, consisting of: 4 N
017.483.1 plug connectors with 2 leads ap-
prox. 150 mm long, soldered.
Hall sensor signal
Ignition trigger signal to ignition output
stage
1 3-pin test lead (e.g. VW VAG 1501).
2 control-unit plug test leads (to be made
up in your own workshop) equipped with
4 N 17.457.2 tab connectors.
. Fuel tank venting activation signal
- Resonance flap activation signal
as well as:
The test leads must always be used for
testing.
Reed switch signal (speedometer)
- ABS wheel sensor signals
D 24128 - 4
DME Diagnosing/Troubleshooting
Printed in Germany - Xxy. 1990