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Using testers and measuring instruments during a road test > < Safety precautions

A1

Working on the fuel system
Working on the fuel system
When working on the fuel system note the following warnings:
  WARNING
The fuel system operates at extremely high pressure. This can cause injury.
t  The fuel pressure in the high-pressure section of the injection system must be reduced to a residual pressure prior to opening the system.
t  Wrap a clean cloth around the connection and carefully loosen the connection to allow the residual pressure to dissipate.
Fuel can escape.
The fuel pump is normally activated when the driver's door is opened. Therefore, unless the battery has been disconnected or the electrical connector for the fuel delivery unit has been unplugged, the fuse for the fuel pump must be removed as a safety precaution before opening the fuel system.
–  Procedure before opening high-pressure section of injection system → Rep. gr.24.
Observe the following to prevent injuries to persons and damage to the injection and ignition system:
t  Always switch off the ignition before connecting or disconnecting electrical wiring for the injection or ignition system or tester cables.
t  Always switch off ignition before washing engine.
t  Entries are stored in event memory of engine control unit if electrical connectors were unplugged and engine was started: Generate readiness code in Guided Functions → Vehicle diagnostic tester.
  Caution
To prevent irreparable damage to the electronic components when disconnecting the battery:
t  Observe notes on procedure for disconnecting the battery.
t  Always switch off the ignition before disconnecting the battery.
–  Disconnect battery → Electrical system; Rep. gr.27.
Perform the following steps before starting to work on the fuel supply system:
  WARNING
Mobile phones can cause an explosion risk.
Ensure that any mobile phones are well clear of the workbay.
  Caution
Electronic components are susceptible to damage.
Observe notes on procedure for disconnecting the battery.
t  Disconnect battery → Electrical system; Rep. gr.27.
t  Briefly open filler cap for fuel tank and close again.
   

Using testers and measuring instruments during a road test > < Safety precautions