Vehicle electrical system, general repair notes

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

CAUTION: When disconnecting and connecting battery, the procedure must be followed as described in the Repair Manual.

Always refer to and heed CAUTION! and WARNING! texts associated with repair and/or removal and installation information in the Repair Manual.

Only the yellow repair cables and insulation tape supplied with VAS 1978 are to be used for wiring/connector repairs. The use of yellow repair wires and yellow insulation tape identifies that a repair has taken place VAS 1978 Instruction Manual.

Before beginning wiring and connector repairs, determine and rectify the cause of damage, e.g.: pinched between metal parts, malfunctioning electrical consumers, corrosion due to water ingress etc.

Avoid loosening or removing any individual Ground (GND) connections (potential for corrosion).

When repairs are completed, always perform a functional check of the component or system. Where applicable, check and erase Diagnostic Trouble Codes (DTCs) and set basic settings where applicable according to Repair Manual and/or VAS 5051/5052.

CAUTION: 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 information in the corresponding Repair Manual for all repairs.
Observe country-specific laws.
Before working on electrical system, disconnect battery Ground (GND) strap.
By disconnecting battery Ground (GND) strap (current disruption), safe work on the electrical system is guaranteed. It is necessary to disconnect battery positive wire only when removing the battery.
Further information, e.g. installing and removing individual components, can be found in the appropriate Repair Manual.
For repairs to vehicle electrical system, soldering is not permitted.
Only perform wiring harness and connector repairs to vehicle electrical system using Wiring Harness Repair Kit VAS1978 or Wiring Harness Repair Set VAS1978A.
Wiring harness repairs may only be carried out using yellow wires.
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. If necessary, lay a wire parallel to the faulty wire.
After crimping, heat-shrink crimp connections using hot air gun to prevent moisture penetration.
Always observe also the supplementary notes for repairing wiring harnesses on airbag- and seat belt tensioner systems, fiber optic cables, CAN-Bus wires, antenna wires and wire cross-sections up to 0.35 mm ² .
Perform a function test after every repair. If necessary, check DTC memory, erase and/or bring systems into basic setting.
If possible, do not loosen Ground (GND) straps from body (danger of corrosion).