Several electrical accessories in the vehicle, such as the fuel injection system, horns, starter, and fog lamps use relays to transmit the electrical signal to the component. Relays use a low-current circuit (the control circuit) to open and close a high-current circuit (the power circuit). If the relay is defective, that component will not operate properly. Most relays are mounted in the engine compartment fuse/relay boxes, with some specialized relays located above the interior fuse box. The covers of the engine compartment relay boxes have a printed key to identify the relays. There are also several relays located above the interior fuse box. If a faulty relay is suspected, it can be removed and tested using the procedure below or by a dealer service department or a repair shop. Defective relays must be replaced as a unit. If you can't determine the correct connection from the wiring diagrams, however, you may be able to determine the test connections from the information that follows. There are six basic types of relays used on these models. Some are normally open type and some normally closed, while others include a circuit of each type. On most relays, two of the terminals are the relay control circuit. The other terminals are the power circuit. Some relays may be marked as an aid to help you determine which terminals are the control circuit and which are the power circuit. To test a relay connect an ohmmeter across the two terminals of the power circuit, continuity should not be indicated. Now connect a fused jumper wire between one of the two control circuit terminals and the positive battery terminal. Connect another jumper wire between the other control circuit terminal and ground. When the connections are made, the relay should click and continuity should be indicated on the meter. On some relays, polarity may be critical, so, if the relay doesn't click, try swapping the jumper wires on the control circuit terminals. If the relay fails the above test, replace it.
