Fuses and Relays — Basic Information (BMW 3 Series E46)

Main fuses

1. Most of the fuses are located behind the glove box on the passenger side, with the remaining fuses installed in a box located in the left corner of the engine compartment.

2. To remove the main fuse box cover, open the glove box, turn the two white tabs and lower the cover. To access the engine compartment fuses, remove the cover mounting screws.

3. The list of circuits protected by each fuse is indicated on the cover of the main fuse box (fig. 3.3, a). In addition, the box has a device for extracting fuses. Keep in mind that fuses installed vertically protect a circuit, and fuses located horizontally are spares. At the top of the box are the "fuse links". The main fuse link is located next to the battery in the engine compartment (fig. 3.3, b).





4. To remove a fuse, first disconnect the corresponding circuit (or ignition), and then pull the fuse out of its clips using the tool attached to the fuse box cover (Fig. 3.4). Inspect the wiring inside the fuse - if it is broken or melted, then the fuse is blown.





5. When replacing a fuse, always install a fuse of the same rating. Never use a fuse with different parameters or replace it with a "bug". Do not replace a fuse more than once until you find out the cause of the malfunction. The fuse parameters are indicated on its head. Fuses are colored differently for easy identification.

6. If a new fuse blows immediately, you need to find the cause of the malfunction before replacing it. The most common cause is a short circuit to ground due to faulty insulation. If the fuse protects several circuits, try to identify the malfunction by disconnecting its circuits one by one (if possible), until it blows again. Your car should always have a set of spare fuses of all ratings, which should be attached inside the fuse box on the bottom.

Relay

7. Most of the relays are installed in the fuse box located behind the glove box on the passenger side (Fig. 3.7), and the remaining relays are located in the engine compartment box installed in its left corner.



8. If you suspect that the relay itself is the cause of a fault in a circuit or system controlled by a relay, turn the system on. If you hear a click when you energize the relay, the fault is due to system components or wiring. If the relay does not operate, it is not receiving main or control voltage, or the relay itself is faulty. To check, replace the relay with a working one. Keep in mind that some relays may look the same and have the same purpose, while others may be similar but perform different functions.



9. Before replacing the relay, turn off the ignition. Pull the relay out of the socket and insert a new one there.