Important Vehicle Information

• Always turn off the ignition or disconnect the battery for resistance tests. (If this is not done, the tester may be destroyed).

• Always disconnect the rpm sensor plug for compression tests. (If this is not done, hazardous high voltages and insulation damage to the ignition coil, high-voltage distributor and ignition leads may result).

• The specified ignition coil (refer to Order No.) must not be replaced by a different coil.

• Never connect a suppression capacitor to ignition coil teminals 1 and 15.

• Never connect ignition coil terminal 1 to ground for burglar alarm. (Ignition coil and control unit may be destroyed).

• Never connect the positive battery terminal or a test lamp to ignition coil terminal 1. (The control unit will be destroyed)

• Never disconnect the ignition lead from ignition coil terminal 4 to high-voltage distributor terminal 4 while the engine is running.

• Voltage flashover from ignition coil terminal 4 to coil terminals 1 and 15 must not occur. (Control unit may be destroyed).

• To avoid destruction of the control unit, the secondary circuit of the ignition system must be suppressed with at least 4 k£2, the original distributor rotor with 1 kii suppression resistance having to be installed.

• Disconnect DME control unit only after turning off the ignition.

• Flashover or disruptive discharge in the area of the high-voltage distributor cap (poor insulation) may destroy the control unit.

• Never disconnect the battery when the engine is running.

• Battery polarity reversal could lead to destruction of the ignition coil and the DME control unit.

• External engine starting with more than 16 V or with a boost battery charger is not permitted.

• When pulling off the connectors, e.g. for air mass sensor, throttle valve switch, injection valves etc., make sure the inside gasket is not lost.

• Always follow the accident prevention regulations when working on the fuel system.

Equipment Required for DME Testing:

- Diagnostics tester 9288 with connecting leads

1 oscilloscope approved by Porsche

1 digital display multimeter with an internal resistance of at least 50 kQ

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, soledered.

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:

Engine speed Vehicle speed ti (injection time) Idle stabilizer Hall signal Tank venting signal VarioCam

Note for USA:

If a fault that affects exhaust gas composition is detected by the Check Engine lamp and is read out, repair is possible with standard workshop tools.

958-24/28

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

The test leads must always be used for the tests!

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