Wires and fuses (Mercedes-Benz E-Class W210)

In Mercedes cars, individual wires are usually bundled and enclosed in a black braid, which makes it difficult to find the necessary wire. In this case, numerous plug connectors can help you find your way around, the exact position of which and the number of incoming wires are indicated in the electrical equipment diagrams. The wire cross-section is selected depending on the power of the consumer: a 0.5 mm² cross-section is sufficient for a control lamp, a 16 mm² wire is required for a starter. A wire that is too thin can overheat, causing the voltage to drop. As a result, for example, 10 or even 9.5 V reaches the headlights instead of 12 V - their light is dim.



Most consumers have two wires connected. But usually only one of them can be traced to the battery or generator. The other wire is often already several centimeters away connected to metal parts of the body, engine or gearbox. This is a clear example of how car manufacturers have used for their own purposes the physical principle according to which metal parts, called "ground" by auto electricians, conduct current. In this way, a large number of wires are saved on closing the circuit from the consumer to the negative terminal of the battery, transferring this function to the "ground". If any consumer does not work, the cause is often a lost contact with the "ground". In this case, contact with the "ground" of this consumer is carried out through bypasses, which causes disturbances in the overall system. A certain amount of endurance is needed to work with electrical equipment. The fuse tables and wiring diagrams presented in this book will help you figure it all out. The mounting block (Fig. 9.36) is located under the cover protecting against moisture and splashes, in the rear right part of the engine compartment.

The negative wire of the battery is connected to the "ground"

Current is supplied to the consumer via a wire, the path of which can be traced to the battery with greater or lesser difficulty, which is also reflected in the electrical diagrams. The return circuit is provided by metal parts of the body or engine that conduct electricity. This saves a large number of wires. In some cases, a short wire is still required for the return circuit - usually when the consumer is located directly on metal parts. These so-called "ground" wires always lead to "ground" points or contacts distributed throughout the body and to which the ends of the wires are connected using threaded connections.

The negative terminal of the battery is connected to the body or to the "ground" as auto electricians call it. Always remember this: "minus" is connected to "ground".