Ignition System: Service Precautions

Safety Precautions

To prevent personal injury and damage to the injection and ignition system, observe the following:

• The ignition must be switched off before connecting or disconnecting injection and ignition system wiring or tester cables.

• Only clean engine with ignition switched off.

• If electrical connectors were disconnected, faults are saved in ECM:

- Connect vehicle diagnosis, testing and information system (VAS 5051B) while ignition is switched off.

- Start "Guided Functions" operating mode.

- Generate readiness code in ECM.


Risk of destroying electrical components when battery is disconnected.

• Observe measures when disconnecting battery.

• Only disconnect battery with ignition switched off.

- Disconnect battery.

If it is necessary to use testing and measuring devices on road tests, observe the following:


Distraction and improperly secured test equipment can lead to accidents.

Risk of passenger airbag deploying in an accident.

• Operating testing and measuring equipment while driving creates a distraction.

• There is an increased risk of injury due to unsecured testing and measuring equipment.

Always secure testers on the rear seat with a strap and have a second person on the rear seat operate them.