The Audi ur-quattro main fuse and relay box
Relays are numbered 1-6 from left to right along the top row, and 7-11 left to right along the bottom row.
| Relay | Rating | Function |
|---|---|---|
| 1 | Fog lights | |
| 2 | Radiator fan - 3rd stage | |
| 3 | Radiator fan - 1st stage | |
| 4 | Headlight washers | |
| 5 | Load reduction relay | |
| 6 | ||
| 7 | Horn | |
| 8 | Bridge (see note) | |
| 9 | Interval wiper | |
| 10 | Fuel pump | |
| 11 | Fresh air blower in air conditioned cars |
Relay position 8 is used in vehicles with automatic transmissions for a relay that inhibits the starter if the shift lever is not in "park". It is useful in the ur-quattro for diagnosing no-start problems where the starter motor fails to react. If volts appear here when the starter is operated, the problem is towards the motor. If no volts appear, the problem is probably the ignition switch or immobiliser.
Fuse functions vary with model years. In general the following should be true for most ur-quattros:
| Fuse | Rating | Functions |
|---|---|---|
| 1 | 15A | Fog lights, air conditioning |
| 2 | 15A | hazard flashers |
| 3 | 25A | Brake lights, ABS |
| 4 | 15A | Radio, trip computer, cigarette lighter, interior light, boot light |
| 5 | Unused | |
| 6 | 5A | Right sidelight |
| 7 | 5A | Left sidelight |
| 8 | 10A | Right headlight main beam, main beam warning light |
| 9 | 10A | Left headlight main beam |
| 10 | 10A | Right headlight dipped beam |
| 11 | 10A | Left headlight dipped beam |
| 12 | 15A | Hazard flasher relay, bulbs in foglight, rear screen heater and hazard flasher switches, function selection switch, reversing lights, air conditioning, gauge lights, WR enrichment, cruise control, electronic thermoswitch (MB/RR) |
| 13 | 15A | Fuel and turbo cooling pumps |
| 14 | 5A | Number plate lights |
| 15 | 25A | Radiator fan relays, rear washer pump |
| 16 | 30A | Heated rear screen, digital dashboard |
| 17 | 30A | Fresh air fan, air conditioning |
| 18 | 30A | Rear wiper motor |
| 19 | 10A | Central locking |
| 20 | 30A | Electric mirrors, heated seats |
| 21 |
The following fuses - along the side of the fusebox - should have red clip-on covers saying "moteur" - if one or more is missing, part # 893 941 819 for a few pence will stop anyone else making the same mistake. Most fuseboxes don't have fuses 29 and 30 - if in doubt, check the fuseholder; any with contacts should also have fuses.
| Fuse | Rating | Functions |
|---|---|---|
| 23 | ||
| 24 | 10A | MB ECU |
| 25 | ||
| 26 | 5A | RR Motronic |
| 27 | 30A | Lambda probe |
| 28 | 15A | Fuel frequency valve (MB), Wastegate frequency valve (MB) Cold start valve (MB), Fuel injectors and air mass sensor (RR) |
The four fuses marked "31" in the diagram are spares.