All sorts of electrical gadgetries in automobiles employ relays to pass on current to elements; if the relay is a bad one, the element will not function. Majority of relays are mounted within the engine compartment fuse and relay box, though other could be mounted at the Junction Block inside the car or at other connectors beneath the instrument panel. If one thinks a relay is faulty, it can be pulled and either checked according to a certain method or by the dealer service department or a repair shop and bad ones come as a relay assembly. Most currently used relays are known as "ISO" type, their terminals are numbered as they indicate their typical circuit connections and uses. The circuit specifies the correct connection of the relay in question, and if the connections cannot therefore be determined from the wiring diagrams, other information may help in identification of test connections. One couple of terminals is the relay control circuit, connected to the relay coil, the other couple of terminals is the power circuit. When activated, the coil produces a magnetic field that closer larger contacts of power circuit to supply power to other circuits for loads. Terminals 85 and 86 are usually associated with the control circuit and certain connections are obligatory if there is a diode or a resistor involved. Terminal 30 is normally connected to the battery voltage for operation of circuit loads and terminal 87 connects to the grounds of circuit. To verify continuity through a relay control coil, there is need to utilize the ohmmeter; it is recommendable to make tests in both polarities. If a resistor is present then the resistance should be the same in both direction but a diode will have more resistance in one direction than the other. If both top and bottom multistep relay resistances are infinite, relay replacement is required. If the relay is disconnected, it is now possible to test between the terminals of the power circuit and no continuity should be found between terminal 30 and 87 when there is no power applied to the coil. To power the relay, insert the fused jumper wire on one side of terminal 86 and the positive terminal of the battery and the other fused jumper wire on terminal 85 to the ground connection and it should click. With these connections continuity should now be from terminal 30 to 87 and if there is a failure in this test the relay should be replaced.
