The switching current circuit is closed only when the corresponding consumer is switched on. Due to this, the magnetic coil, overcoming the spring force, attracts a powerful contact and closes the working current circuit.
In order to avoid voltage drop, the operating current is supplied via the shortest route to the relay, and from there, when the switch contacts are closed, to the consumers. Due to this, a large current does not flow through the switch contacts. In addition, voltage losses that could occur due to long wires between the switch and the consumer are eliminated. In addition, there are relays that include certain functions.
The relays are located on relay panels, which also contain special fuses. These panels include, for example, the panel in the electronics unit in the battery section, which marks the fuel injection and engine management system power relay, the relay for the additional air pump, and the automatic transmission. The fuses for the electronic digital engine control unit and the additional air pump are also located on this panel.
Panel for nine relays (instrument panel): 1 - fuel pump relay, 2 - control device relay for controlled hydraulic drive, 3 - two-tone horn relay, 4 - brake booster relay, 6 - unloader relay for contact X. B - fuse with thermal relay, 5, 7, 8, 9 and A - not occupied.
Panel for three relays: 2 - relay for low heat output, 3 - relay for high heat output, A - fuse for independent heater, B - fuse for glow plugs (coolant), C - fuse 2 for glow plugs (coolant), 1 - not busy.
Panel for four relays with threaded connection: 1 - not occupied, 4 - taxi relay, A - not occupied, B - optional: burglar protection, C, D and E - not occupied. F - 10 A fuse for special purpose vehicles, G - 60 A fuse for the V6 radiator fan, H - fuse 1 to 50 A for the ABS control unit (5123), 2 and 3 - not occupied.
Panel for four relays in the electronics unit (battery section): 2 - fuel injection system and engine management system power supply relay, 3 - additional air pump relay, 4 - automatic transmission relay, A - fuse for the electronic digital engine management system, B - fuse for the additional air pump, 1.1, 1.2, and C - not occupied.
This publication is borrowed from the resource AudiManual.ru