Mercedes M-Class W163

since 1997 of release

Repair and car operation

Mercedes W163
+ Mercedes-Benz Cars of a class M (W163)
+ Governing bodies and receptions of safe operation
+ Current leaving and service
+ Engine
+ Systems of cooling, heating and air conditioner
+ the Power supply system and production of the fulfilled gases
+ Systems of electric equipment of the engine
+ Manual box of gear shifting
+ Avtomaticheckaya transmission
+ Transmission line
+ Brake and auxiliary systems
+ Suspension bracket and steering
+ Body
- Onboard electric equipment
   General information and precautionary measures
   Search of causes of failures of electric equipment
   Safety locks - the general information
   Chain breakers - the general information
   The relay - the general information and check of serviceability of functioning
   Digital tire of data of CAN
   + Assembly blocks, elements of control systems
   + Dashboard, switches, traveling computer
   + Driving electromotors
   + Alarm and lighting devices, sensors of a rain and temperature of external air
   + Systems of additional safety (SRS)
   + Audiosystem
   + Schemes of electric connections

The relay - the general information and check of serviceability of functioning

General information

For giving of power supply or a management signal on many of consumers of the electric power in the car (such as components of system of injection of fuel, a horn, a starter, the fan (ы) cooling systems, fog lights and so forth) are used by the relay. Actually, the relay represents the electric key providing short circuit of VV of a contour on NV to a signal. In case of a relay exit out of operation there is a refusal of functioning of the corresponding consumer. The most part of the relay is located in an impellent compartment, others "are scattered" on the car. The description of check of serviceability of functioning of the relay is provided below. The failed relays are subject to replacement.



  1. Always it is possible to determine correctness of connection of the relay by Schemes of electric connections.
  2. Usually the management contour always is connected to two of contact plugs of the relay. When giving on these NV plugs of tension the current starts to circulate on a winding of management of the relay therefore there is a short circuit of big contacts of a working contour of the consumer of the electric power. Other plugs are plugs of working (VV) of a contour and become isolated among themselves when giving food on a management contour.
  3. For the purpose of simplification of identification of plugs of the relay explanatory marking is usually put on its case with the image of the scheme of connection of keys. If similar marking is absent, it is necessary to address to schemes of electric connections.
  4. For check connect an ohmmeter between two VV plugs of a contour of the relay, - in the relay of normally opened type conductivity should be absent. Now connect the wire crossing point equipped with a safety lock between one of plugs of management of the relay and the positive plug of the battery (In +). By means of other wire crossing point earth the second plug of management, - the relay should publish click after which the ohmmeter will fix conductivity existence (the relay of normally opened type). Some relays demand obligatory observance of polarity of connection.
  5. At negative result of check replace the relay.