Audi A4

since 1994 release

Manual of the car

Audi A4
+ Running gear
+ Regular servicing
+ Engines
+ Turbo-supercharging
+ System of an exhaust
+ Cooling system
+ Fuel tank and fuel pump
+ Air filter and channels of absorption
+ System of injection
+ Coupling
+ Transmission and main transfer
+ Suspension bracket of wheels and steering
+ Brakes
+ Wheels and tires
- Electrotechnical equipment
   Minus is connected to weight
   The help for orientation in the electrotechnical equipment of the car
   Connections of wires
   Central switching knot
   Support of additional relays
   Box for electronics
   Relay and control units
   Switching relay
   H-contact of the relay of unloading
   Table of the relay and control units
   Safety locks
   Table of safety locks
   + Electric circuits
   + Accumulator
   + Generator
   + Starter
+ System of ignition
+ Lighting
+ Alarm equipment
+ Tools and devices
+ Heating and ventilation
+ Body details
+ Salon
Search of malfunctions
Technical characteristics


H-contact of the relay of unloading

The unloading relay (the ordinary switching relay) plays a significant role in the onboard electrician. Therefore here its function is described:
On the ignition lock plug 75 current arrives only if the ignition key is in situation "Is included". Powerful consumers of current, for example, screen wipers, the warmed back glass or the supercharger of air, are connected to this plug in order that at start of the engine on a starter there was all power of the accumulator. Certainly, not all these consumers can receive power supply through contact with the ignition lock; for this purpose it is too weak. Therefore between them the relay through which working contact giving of current is carried out has to be connected. The contact of the lock of ignition (along with giving of current on headlights and the coil of the relay of a sound signal) provides only giving of switching current to the relay.