Instrument cluster and switches in the cabin (Mercedes-Benz E-Class W210)

The switch closes the electrical circuit of the corresponding device. In the E-class cars, Mercedes-Benz used a completely new generation of switches. All buttons, rotary, sliding, push and other switches are ergonomic and easy to use.

Combination switch

The direction indicators, windshield wiper and light signal are controlled by a single steering column switch on the left side of the steering wheel. The light control is also located there: a combined switch for the parking light, low beam and fog light, rear fog lights, and a headlight corrector.

This switch (designation "S4" on the wiring diagrams) is a truly complex mechanism, since at least 12 wires are connected to it and connected in different ways. Such a combination switch was also installed on previous Mercedes models. Over the years of operation, the following problem arose: as the turn signal switch wears out, it stops locking. In this case, the combination switch was subject to replacement. Attempts to improve the locking system often brought only temporary improvement.

Combination of instruments and switches

All important control switches are located on the central console (Fig. 10.7). For convenience, the switches are divided into functional groups:

• in the top row there are switches for the rear headrests, central locking and hazard warning lights;
• in the middle part the control unit for the heating system, air conditioning and recirculation button are located;
• at the bottom the central console contains a block of switches for controlling the electric windows, a child safety lock and buttons for adjusting the outside rear-view mirrors.

Looking up, you can see the new control unit for the interior lighting and the sliding sunroof. The ventilated sensor for the heating and air conditioning system is also located here.

(Material based on data from the portal: MercedesMan)

Electronic engine starting system

The switch of this system is practically the most important in the car and also a new development. Electronic ignition switch - the main idea is clear from the name. The ignition switch and ignition key in the traditional sense are no longer in the Mercedes E-class. They were replaced by a complex electronic system, in which the usual mechanical key was replaced by a device with several functions. The main difference of the electronic key is the absence of a metal pin: to start the engine, a wedge-shaped tongue is inserted into the ignition switch socket and turned to the right. Everything else is done by electronics. On models with an automatic transmission, it itself carries out the start procedure before starting the engine.



However, first, a split-second control process takes place inside the ignition switch, during which the electronics automatically check whether the correct key is inserted into the lock. To do this, the switch inductively supplies power to the key, which in turn transmits a coded signal via infrared radiation. The microprocessor in the ignition switch compares the code with the value stored in memory and, if it matches, releases the electric steering wheel lock. Now the key can be turned to the right to turn on the ignition. The codes of the electronic key and the value stored in the processor memory are changed and re-saved in memory with each new start.

It is more convenient to check the ignition switch from the side of the contact connector under the steering column. The symbols on the switch indicate which contacts are connected in the corresponding position of the key. If faults occur, replace the ignition switch at a service station, since a special tool is required to remove it and the steering column.

Security system (access system)

Since December 1994, Mercedes-Benz has been equipping all models as standard with an electronically controlled security system that meets the stricter requirements of the law and motor insurance companies. The central element of the new security system is an infrared remote control designed as an electronic door key. To start the engine, the car door must first be opened using this remote key. Otherwise, the engine control system will remain locked and the engine cannot be started.



A small transmitter in the key emits an invisible infrared signal, combined with a radio signal, to several receivers located inside the doors and behind the interior rearview mirror. The received and processed signal is transmitted to the control unit in the engine compartment. There, the signal is stored in memory, and a new code is generated, which will be needed for the next (or later) opening the doors and starting the engine. At the same time, data is exchanged with the engine control unit to block the start and the central door locking system.

Hazard warning switch

The hazard warning light switch button is dimly illuminated by a small lamp when the lights are on. This is because the lamp receives voltage through a resistor. When the button is pressed, the resistor is disconnected from the circuit and the lamp begins to shine at full power in a flashing mode.

Checking switches

If you need to check a switch when troubleshooting electrical equipment, first find it on the diagram and then check its connection. To do this, you can use either a test lamp and check for voltage, or an ohmmeter in the removed state. In most cases, the first method is preferable. Check whether the needle of the test lamp can reach the wire being tested in the contact connector. If not, the tip can pierce the insulation. Two-position switches can only be removed after dismantling the trim. Other switches are screwed on. Many switches in a car have internal lighting. Unfortunately, the lamps in them cannot be replaced, with the exception of the light switch.

Sequence of works

1. The needle of the test lamp can be used to pierce the insulation of the wire to check for voltage on them.

2. Have the appropriate wiring diagram at hand.

3. First check if there is voltage at all on the switch. To do this, turn on the ignition or lighting.

4. Then check whether the switch transmits voltage in the appropriate position.

5. Using the ignition switch and starter as an example, the check should be carried out as follows:

• the red current-carrying wire from the positive terminal of the battery must always be energized;
• there should be current on the wire of terminal "15x" of the ignition switch when the switch is in the positions "I", "II" and the starter is on;
• there should be current on the wire of terminal "15" of the ignition switch when the switch is in the "II" position and the starter is on;
• the current should flow on the purple wire of contact "50" only when the switch is in the starter on position.