Several electrical accessories in the vehicle utilize relays to transmit electrical signals to components, and a defective relay will prevent proper operation of that component. Various relays are grouped in different locations, with some located in the convenience center under the right side of the dashboard behind the sound insulator panel, while later models have this center under the left side of the instrument panel. To test a relay, it's advisable to consult the wiring diagram for the circuit to determine the correct hook-ups; if that's not possible, the following information may assist. Most relays have two terminals for the control circuit, which connect to the relay coil that closes the large contacts when energized, while the other terminals form the power circuit, connected internally when the control circuit is energized. Relays are typically marked to help identify control and power circuit terminals. To test, connect a fused jumper wire between one control circuit terminal and the positive battery terminal, and another jumper wire between the other control circuit terminal and ground; the relay should click upon making these connections. If it doesn't click, polarity may be critical, so swapping the jumper wires on the control circuit terminals may be necessary. With the jumper wires connected, check for continuity between the power circuit terminals as indicated by the relay markings. If the relay fails any of these tests, it should be replaced.