Using electrical diagrams (Mercedes-Benz C-Class W202)

If you need to identify a fault in the electrical system or install additional electrical fittings, you cannot do without a wiring diagram. Based on it, the current path and, thus, the wire connections are identified. The corresponding electrical circuit must be closed, otherwise the electric current may not flow. This is not enough, for example, when voltage is applied to the positive terminal of the headlight, if the electrical circuit is not simultaneously closed through the connection to the housing.

Switches, relays, fuses, measuring devices, electric motors or other electric elements may be installed in individual electric circuits. In addition to the circuit itself, the explanation of the circuit diagram contains switching components with the corresponding position coordinates. Each circuit diagram is divided into search fields by letters (from A to M) on the left and right edges, as well as by numbers on the upper and lower edges. The found communication component of the circuit diagram is located at the intersection point of the horizontal and vertical lines, originating from the corresponding letter and belonging to this number, which are located in the explanation behind the circuit element in the form of position coordinates.

Vehicle variants and special equipment are framed by a dashed line and marked with a symbol, which is given on the following page or in the corresponding explanation. The direction of movement in the diagram is represented by the symbol "X". The numbers at the points of connection of wires to consumers, switches, etc. coincide with the marking of these parts in the vehicle. At the same time, slightly larger numbers indicate the marking of the terminals of a separate electrical circuit. In order to better trace the passage of wires, individual connecting wires have different colors.