In the fuel injected vehicles, the
Horns, starter, and the fog lamps all employ relays for passing electrical signals to the parts of the vehicle. A relay works on a low current control circuit controlling a high current power circuit and in case of a faulty relay, it will affect the performance of the related part. Most of the relays are placed in the engine bay and in interior fuse/relay boxes, while other relays are distributed around the car's body; there is a panel next to the right side of the engine bay. If the relay is thought to be at fault, it can be switched out on alterative and tested either by going through a known procedure or through a service center. To test it, turn the switch on, connect a fused jumper wire from the terminals from the control circuit and the positive terminal of the battery and the other end of the jumper to ground; the correct functioning of the relay can be confirmed by a clicking sound. Standard four-terminal relays can be tested for continuity with an ohmmeter but for five terminal relays with diodes, the battery polarity has to be connected properly for continuity testing. In some circuits such as blower motor circuit, the usage of six-terminal relays is done with one control circuit and two power circuits and continuity must be tested on terminals which are designated for this test. Any relay that does not meet these tests should be replaced.