Fuses and relays - general information

Body electrical system / Fuses and relays - general information

Main fuses
1 The fuses are located beneath the bonnet on the left-hand side of the plenum chamber/bulkhead. Access is gained by squeezing the sides of the plastic lid at the top and bottom (see illustration). Take care not to damage the seal.

3.1 Removing the plastic lid from the fuse box

2 The fuse circuits are given in the wiring diagrams at the end of this Chapter.

3 Blown fuses are easily recognised by the metal strip being burnt apart in the centre.

Make sure that new fuses are firmly held between the terminals.

4 To remove a fuse, first switch off the circuit concerned (or the ignition), then pull the fuse out of its terminals. The metal strip within the fuse should be visible; if the fuse is blown it will be broken or melted.

5 Always renew a fuse with one of an identical rating; never use a fuse with a different rating from the original or substitute anything else. Never renew a fuse more than once without tracing the source of the trouble.

The fuse rating is stamped on top of the fuse; note that the fuses are also colour-coded for easy recognition.

6 If a new fuse blows immediately, find the cause before renewing it again; a short to earth as a result of faulty insulation is most likely. Where a fuse protects more than one circuit, try to isolate the defect by switching on each circuit in turn (if possible) until the fuse blows again. Always carry a supply of spare fuses of each relevant rating on the vehicle, a spare of each rating should be clipped into the base of the fusebox.

Relays
7 The main relays are near the fusebox in the left-hand side of the plenum chamber/ bulkhead. Other relays are beneath the lefthand side of the facia panel and behind the ECU on the bulkhead (see illustrations).

3.7a Relays located beneath the left-hand side of the facia panel

3.7b Relay located behind the ECU on the bulkhead

8 If a circuit or system controlled by a relay develops a fault and the relay is suspect, operate the system; if the relay is functioning it should be possible to hear it click as it is energised. If this is the case the fault lies with the components or wiring of the system. If the relay is not being energised then either the relay is not receiving a main supply or a switching voltage or the relay itself is faulty.

Testing is by the substitution of a known good unit but be careful; while some relays are identical in appearance and in operation, others look similar but perform different functions.

9 To renew a relay first ensure that the ignition switch is off. The relay can then simply be pulled out from the socket and the new relay pressed in.