Vehicle Electrical System, General Repair Information

WARNING: This page is about a different variant/trim than selected.

CAUTION:

When disconnecting and connecting the Battery -A-, the procedure must be followed as described in the repair information. Refer to BATTERY, DISCONNECTING AND CONNECTING .

WARNING:

Some tools are supplied with a tool safety clip, which is slid over the tool points after using the tool, in order to protect other workers from injuries and tool points from damage.

Observe the current notes in the corresponding repair information for all repairs.
Follow the regulations specific to the country.
Disconnect the Battery -A- before working on the electrical system. Refer to BATTERY, DISCONNECTING AND CONNECTING . By disconnecting the Battery -A- (current disruption), the electrical system is guaranteed to be safe to work on. Disconnecting the positive battery cable is only required when removing the Battery -A-.
Before beginning any repair work, always eliminate the cause of damage, for example sharp body edges, faulty components, corrosion, etc.
Further information, for example, installing and removing the individual components, can be found in the appropriate repair information.
Soldering is not permissible for repairs to the vehicle electrical system.
Wiring harness and connector repairs to vehicle electrical system may only be performed using the Wiring Harness Repair Set: VAS1978 /Wiring Harness Repair Set: VAS1978A /Wiring Harness Repair Set: VAS978B .
Exclusive use is to be made of yellow wires for wiring harness repairs.
Wiring harness repairs may not be performed again in the wrapping of the vehicle-specific wiring harness and are to be marked with yellow adhesive tape.
These yellow wires and every location on wiring harness wrapped in yellow insulating tape indicates a previous repair.
Crimp connections must never be repaired. Route a wire parallel to the faulty wire.
After crimping, the crimp connectors must be heat-shrunk using the Wiring Harness Repair Set - Hot Air Blower: VAS1978/14A to prevent moisture penetration.
Always pay attention to the supplementary notes for repairing wiring harnesses on the airbag system and belt tensioners, fiber optic cables, CAN-Bus wires, antenna wires and wires with cross-sections up to 0.35 mm ² . Refer to 0.13 MM .
A function test must be performed after every repair. If necessary, the DTC memory must be checked and deleted, and/or the system reset to the basic setting.
If possible, do not loosen ground straps from body (danger of corrosion).
Not all wire cross-sections in the vehicle are contained in the Wiring Harness Repair Set: VAS978B and its previous versions. If the required wire cross-section is not present, the next greater cross-section must be used.
Shielded harnesses may not be repaired. If faulty, the entire harness must be replaced.
Heat-resistant wires have been installed in the vehicle at various locations, mainly in the engine compartment. Heat-resistant wires can be recognized by their somewhat duller and softer insulation. Only heat-resistant wires may be used to repair these wires.