This material provides information on the locations and diagrams of fuses and relays on the Audi 90 80 B4. This model was presented by Audi in 1991. The main difference from the previous B3 is the updated design of the hood, bumper and headlights. A better material was used in the interior trim and airbags appeared. Newly designed rear axle and gas tank. This model was produced in 1992, 1993, 1994 and 1995. 
The Audi 90/80 b4 has two main relay and fuse boxes. The main one is located under the soot space of the engine compartment, on the left side, closer to the wipers. The second is under the dashboard in the cabin.
Engine compartment fuse box
- relay
- diagnostic connector
- fuses 1-21. Diesel vehicles have 22 fuses.
- additional fuses 23-32
- four spare fuses
- relay designation on the cover of the distribution panel
- clip for removing and installing fuses
The data presented is universal. Check the description on the back of the protective cover.
Diagram
Designation
| No. | Appointment |
| 1 | 15A Fog lights, rear fog lights |
| 2 | 15A Alarm |
| 3 | 30A Horn, seat heating |
| 4 | 15A Electronic clock, trunk lamp, interior lighting, cosmetic mirror, reading lamp, cigarette lighter, on-board computer, automatic air conditioning, radio, self-diagnosis system |
| 5 | 30A 2nd speed of rotation of the radiator blower fan |
| 6 | 5A Rear right side and parking lights |
| 7 | 5A Rear left side and parking lights |
| 8 | 10A Right high beam headlamp, high beam warning light |
| 9 | 10A Left high beam headlamp |
| 10 | 10A Right headlamp dipped beam, electric motor for adjusting the position of the right headlight |
| 11 | 10A Left low beam headlamp, left headlamp adjustment motor |
| 12 | 15A Instrument panel, reversing lights, control system, automatic transmission, differential lock, on-board computer, speed control, retarder relay, interior lighting with, electronic thermal switch, relay for turning on the radiator blower |
| 13 | 15A Fuel pump |
| 14 | 5A License plate lighting, instrument panel lighting, engine compartment lamp, glove compartment lighting, automatic air conditioning |
| 15 | 25A Direction indicators, wiper, glass washer pump, heated glass washer jets, radiator blower relay, air conditioning |
| 16 | 0A Heated rear window, heated mirrors |
| 17 | 30A Interior blower, automatic air conditioning |
| 18 | 5A Electric mirrors |
| 18 | 15A Rear window cleaner (Avant) |
| 19 | 10A Central locking, heating of the lock switch cylinder, anti-theft system |
| 20 | 30A Radiator blower fan, 1st speed, passenger compartment fan |
| 21 | 10 Diagnostic socket |
| 22 | Not used (cars with gasoline engines) |
| 22 | 80A Glow plugs (vehicles with diesel engines) |
Additional fuses audi b4 lower row (if any)
| 23 | Not used |
| 24 | Not used |
| 25 | 5A Heated lambda probe. Not used for diesel vehicles |
| 26 | 30A Trailer connector |
| 27 | 10A Ignition / fuel injection system |
| 28 | 10A Ignition / fuel injection system. Not used for diesel vehicles |
| 29 | 10A Stop light |
| 30 | 5A Speed control (vehicles with automatic transmission), Not used for vehicles with diesel engines. |
| 31 | 15A ABS, differential lock |
| 32 | 10A Ignition / fuel injection system On vehicles with TD diesel engines – fuel cut-off valve |
Fuses 27 and 28 can be fitted with a red plastic cap with the word “Motor / Moteur”
The fuse number 4, 15A, is responsible for the cigarette lighter.
Relay
- Relay for fog lamps and taillights. For cars without fog lights, a jumper is installed in this place.
- Radiator fan relay (for vehicles without air conditioning), radiator fan relay for switching on the 2nd stage of rotation
- Relay for switching on fans
- Headlight washer relay
- X-contact unload relay
- Relay for blower fans (manual air conditioner), air conditioner fan relay for 2nd stage rpm (air conditioner with automatic control)
- Horn relay
- Anti-theft alarm relay (vehicles with manual transmission). Cars without such a system have a jumper. For cars with automatic transmission, this space is free.
- Wiper Interval Relay
- Fuel pump relay
- Radiator blower relay for switching on the 1st stage of rotation.
Attention! For vehicles with diesel engines pos. 2 and 3 are not occupied and relay 10 is the preheating plug relay.
Passenger compartment relay box
To access the box, unscrew the 4 screws and remove the protective cover.
Diagram
On different versions, not all relays may be busy.
Assignment
- ABS system
- Seat belt warning light
- Interior lighting control unit
- A / C clutch relay box
- Wiper and glass rear window washer
- Oil pressure monitor, front light control unit
- Not used
- Not used
- Automatic gearshift lock (only for vehicles with automatic transmission)
- Not used
- Not used
- Heated passenger seats
- Heated driver’s seat
- Car sunroof relay
- Control unit for sunroof and door windows with electric drive
- Control unit for sunroof and door windows with electric drive
- Anti-theft warning lamp relay
- Power Door Windows, Power Sunroof, Power Seat Circuit Breaker
Changes for diesel vehicles
5 – electric current relay 12 – acoustic signal relay (door not closed, not wearing a belt) 13,14 – exhaust gas recirculation control relay 15 – lighting lamp control relay 18 – relay for the 3rd speed of rotation of the radiator blower fans (usually it is the 2nd speed) K – fuse for radiator blower S – fuse for electric current.
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