System Diagnosis

Equipment Required for DME Testing:

1- Diagnostics tester 9288 with connecting leads
1- oscilloscope approved by Porsche
1- digital display multimeter with an internal resistance of at least 10 Mohm
1- Bosch L-Jetronic test lead, Bosch No. 1684 463 093 (check lead for correct polarity at plugs)
2- control unit plug test leads (shop-made) with 2 tab connectors no. 17.457.2 fitted to avoid damage to the plug terminals in the control unit plug during testing.
2- adapter test leads, consisting of: 4 plug connectors N 017.483.1 with 2 leads approx. 150 mm long, soldered.
1- three-pin test lead (e.g. VAG 1501).

Test Lead:

2- control unit plug test leads (shop-made) with 4 tab connectors N 17.457.2.

CAUTION: The test leads must always be used for the tests!

All sender and ignition timing signals of Porsche vehicles can be checked with the engine testers recommended by Porsche. Since instructions for connection of testers on a car will differ depending on the equipment manufacturer, these instructions must always be followed to ensure correct tester connection.


The following signals can be checked with the oscilloscope:
^ Speed sensor signal
^ ti signals
^ Idle speed control activation signal
^ Hall sensor signal
^ Ignition trigger signal to ignition output stage
^ Tank venting activation signal
^ Activation signal for resonance plate as well as:
^ Reed switch signal (speedometer)
^ ABS wheel sensor signals

System Diagnosis:

Refer to the chart for system problem determination. If fault codes are present, follow test points in order of code display. If no codes are present or Bosch tester 9288 or 9268 is unavailable, follow applicable test points in numerical order for diagnosis. Complete all applicable test points and check component wiring before replacing or suspecting DME control unit. If a component is found to be defective, verify that original complaint has been resolved after replacing. If symptoms persist, return to beginning of diagnostic chart.