Contents: Wire connectors ↡ Battery power cables ↡
Contact "15" is energized only when the ignition is on (the key in the lock is in position "II"), while outside the ignition coils, current is supplied to those consumers that should receive voltage only when the engine is running. The wires on the contacts "15" have a black braid, sometimes with the addition of colored stripes for certain units.
Contact "15R" designates contacts that must function in the key positions "I" and "II", as well as when the starter is turned on. The braid is usually black with additional stripes.
Contact "30" is constantly under voltage from the battery or, when the engine is running, from the generator. Therefore, if the tool is handled carelessly, short circuits or sparking are possible if the negative terminal is not removed from the battery. The connected wires are current-carrying and usually have a red braid, with additional stripes of a different color added if necessary.
Contact "30a" is constantly under voltage from the positive pole of the battery through the fuse. Usually, memory units of controller fault codes are connected through it.
Contact "31" - "ground" through which consumers are connected to the "ground" of the car to close the circuit. The wires have a brown braid.
Contact "49" is responsible for the direction indicator and hazard warning system. The color of the wires is black and green with additional stripes of a different color.
Contact "50" – through it, voltage is supplied to the starter during starting. The main color of the wires is purple.
Contact "53" is responsible for the windshield wiper.
Contact "56" is responsible for supplying voltage to the low beam headlights through the yellow wires and to the high beam headlights through the white wires.
Contact "58" is responsible for the parking and side lights, as well as the license plate lighting. The main color of the wire braiding is gray, each with an additional strip of a different color.
Contact "61" is responsible for the charging indicator light ("D+"), the wire color is blue.
Contact "87" it is usually powered, like contact "15", but through a relay, for example, overvoltage protection.
Wire connectors
For a long time, according to ADAC statistics, disconnected connectors were one of the most common causes of malfunctions, and practically all cars. Against this trouble, which happens especially often after six years of operation, Mercedes has applied several innovations. First of all, the car uses many expensive silver-plated round plugs. The connector combs have additional mechanical protection. It is clear that this protection must be surmountable to disconnect the connections. Therefore, it is either a bracket or two side latches that must be pressed to disconnect the connector. Some plugs are equipped with rotary or spring locks. Where possible, the connectors and devices are well protected from moisture.
Battery power cables
Fig. 9.37. When the upholstery is removed, the power cable (1) coming from the battery in the driver's footwell is visible; steering wheel shaft (2) with extension for adjustable steering column; red plug connection (3) to the airbag
To supply current from the rear-mounted battery to the engine compartment, a large-section red power cable is connected to the positive terminal of the battery (Fig. 9.37). It then passes through a thick (50 mm²) black cable laid along the driveshaft tunnel and ends with a 3-pin connection (X4) in the accelerator pedal area.
From there, the wires go to the starter and other units, to the ignition switch, fuse box, lighting module, generator, heating system and the jumper contact (X 12/3) in the engine compartment. A capacitor (C2) is also installed in the contact connector to suppress interference.