Engine Fails to Start

WARNING: The electronic ignition system generates voltages of 40,000 V. This voltage can prove fatal to people with weak hearts or those who are fitted with pacemakers. The ignition system should therefore be treated with great respect.






FAULT DIAGNOSIS, IGNITION - ENGINE FAILS TO START

Fault symptom
Engine fails to start.


DIAGNOSTIC PROCEDURE

1. Checking The Operation Of The Ignition Coils
Connect the Scan Tool. Ignition switch in the ON position.
Select "ACTIVATE".
Select "IGNITION COILS"
Select "IGNITION CYL1", "CYL2", "CYL3" and "CYL4". Each individual ignition coil must be selected separately.
An ignition coil is activated for 10 seconds at 200 Hz. For longer activation the command must be repeated.
Listen for the sound of each ignition coil working.

If all the ignition coils are working, continue with point 5.

If no ignition coil is working: Continue with point 2.

If only one or some of the ignition coils are working, continue with the "Fault diagnosis, ignition- misfiring". Ignition - Misfiring






2. Checking The Ignition Discharge Module Voltage Supply
Unplug the ignition discharge module's 10-pin connector.
Ignition switch in the ON position.
Connect the test lamp to pins 10 and 6 of the ignition discharge module connector.
Activate one of the ignition coils by means of the Scan Tool. The purpose of this is to get the main relay to operate.
The test lamp should light up.

If the test lamp lights up, try fitting an ignition discharge module that is known to be OK.
Start the engine, change the original ignition discharge module. If the engine fails to start, continue with point 5.

If the test lamp does not light up, continue with point 3.






3. Checking The Ignition Discharge Module's Connection To Ground
Connect the test [amp to battery positive and pin 6 of the ignition discharge module's connector.

The test lamp should light up.

If the test lamp lights up, continue with point 4.

If the test lamp does not light up, check the wiring, including grounding point G7P, and rectify as necessary.

4. Checking The Ignition Discharge Module's 12V Supply
Connect the test lamp to pin 10 of the ignition discharge module's connector and battery positive.

Activate one of the ignition coils by means of the Scan Tool. The purpose of this is to get the main relay to operate.

The test lamp should light up.

If the test lamp lights up, continue with point 6.

If the test lamp does not light up, continue with the fault diagnosis, main relay, Main Relay

IMPORTANT: The ignition discharge module must be positioned with the ignition coils facing downwards during the step 5 test to ensure that the transformer oil effectively insulates the high-tension part of the ignition coils.





5. Checking The Operation Of The Ignition Discharge Module
Detach the ignition discharge module from the camshaft cover. Fit test spark plugs (part No. 86 11 386) in the ignition discharge module. Ground the spark plugs using cable 86 10 867. Use the Scan Tool to activate each individual ignition coil.

Each spark plug that is activated should produce a spark.

If sparks are produced, change the spark plug. If no sparks are produced, change the ignition discharge module.

6. Final Check
Start the engine and check whether the fault symptoms persist. If they do, refer to Before Replacing A Control Module.