Detecting poor grounding (VW Golf 4)

The negative terminal of the battery is connected to the "ground" - the metal of the body, engine or gearbox; many electrical components are connected in such a way that only the positive wire is connected to them, and the current returns to the battery through the metal of the body. This means that the fastening of the electrical component and the body are part of the electrical circuit. As a result, a poor or rusty fastening can cause the component to fail or lead to its unstable or poor operation. In particular, light bulbs may burn with a dim light (especially if the grounding point of this light bulb is used to ground some other electrical equipment element that is switched on), electric motors may operate slowly, and the operation of one circuit may have subtle effects on the operation of another circuit.

Keep in mind that many vehicles use ground wires between certain components, such as the engine/transmission and the body, where there is no direct metal-to-metal contact due to soft rubber mounts or paint.

To check the reliability of the element grounding, disconnect the battery and connect one of the ohmmeter probes to a reliably grounded element. Connect the other probe to the wire or connection to the body that needs to be checked. The resistance shown by the ohmmeter should be zero; if not, check the connection as follows.

If you suspect a missing ground, disassemble the connection and clean the body area and wire terminal (or the element's grounding surface) to bare metal. Carefully remove all traces of dirt, then use a knife to remove all paint so that reliable contact between the two metal surfaces is achieved. When reassembling, tighten the connector securely; when connecting the wire terminal, place a serrated washer between the terminal and the body surface to ensure a secure connection. When connecting, prevent future corrosion by applying a layer of Vaseline or silicone grease.

(The original information is posted on the resource: www.vwmanual.ru)