BMW X3 Service & Repair Manual: Instructions for welding work (overload protection of control units)

CAUTION: Follow instructions for body repairs.

When performing welding work on installed control units, to avoid any defects in the electronic control units, observe the following steps:

• Observe instructions for disconnecting and connecting battery.
• Detach terminal of battery negative lead from car battery and second battery if fitted. Cover negative terminal posts.
• If welding is to be performed near the battery/batteries, first remove battery/batteries from vehicle (flying sparks - combustion of explosive gas).
• Fit return clamp on welding unit as close as possible to welding point (maximum distance approx. 1 m).
• Never connect return clamp to ground pin on body which has ground wires attached!

INSTRUCTIONS ON COMPONENT TESTING

NOTE:

• During all inspections and work on engine electrics and electronics, always observe safety regulations and accident prevention specifications.
• Always disconnect connectors of control units or components before checking electric wires.

Testing Aids:

• Schematics, refer to Diagnosis Information System (DIS).
• Only ever use test lines, adapters, terminals and test tips manufactured by specialists, refer to Diagnosis Information System, Repair Manual.
• The inspection values for component testing are located in the Diagnosis Information System (DIS).
• For further technical information, refer to Technical Data.

INSTRUCTIONS FOR CONNECTING AND DISCONNECTING TEST UNITS

When connecting and disconnecting:

• Service Tester
• testing devices
• test leads and
• when replacing control units

it is essential to turn off the ignition!

FOLLOW INSTRUCTIONS FOR REMOVING AND INSTALLING ELECTRONIC CONTROL UNITS.

Follow operating instructions for testing devices.

Make sure that connected test leads cannot make contact with rotating parts (e.g.: fans, ribbed V-belts, etc.).