Toyota Relay

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 to open and close a high-current circuit. If the relay is defective, that component will not operate properly. Most relays are mounted in the engine compartment fuse/relay box, with some specialized relays located in the underhood box at the right fender. On some models, the ABS relays are located in a separate underhood relay box at the left side of the radiator. If a faulty relay is suspected, it can be removed and tested. Defective relays must be replaced as a unit. Identification of the circuit the relay controls is often marked on the top of the relay, but the decal or imprint inside the cover of the relay box should also indicate which circuits they control. 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. If the relay fails the test, replace it.