Chevrolet 13598349 Relay

Relays carry out the transmission of electrical signals to many electrical accessories found in vehicles, including fuel injection system, horns, starter, and fog lamps. The low-current circuit (the control circuit) is used by relays to open and close a high-current circuit (the power circuit). Defective relay may cause the related component to malfunction. Most relays are located in the engine compartment and interior fuse/relay boxes with primary fuse/relay panel being found in the engine compartment upon unlocking the tabs and removing both the outer and inner covers. To diagnose a suspected faulty relay, remove it for testing according to the procedure described or contact a dealer service department or repair shop where defective relays must be replaced as complete units. When testing relays, you should remember: Most of these vehicle's relays follow "ISO" relay standard which means International Standards Organization. These ISO relays have numbered terminals that indicate their normal circuit connections and functions. External labels often exist on these vehicles' relays that show control and power circuits for easy identification because they have two basic terminal layouts. Generally, terminals 85and 86 represent typical relay control circuits connecting them to the coil while other relay terminals relate to power circuitry. On energizing the relay, its coil produces a magnetic field that closes larger contacts within the power circuitry to drive loads on this circuitry. Typically, terminal 86 is connected to battery positive (B+) voltage while terminal 85 is grounded via diode; for resistor cases one could connect terminals either way with respect to B+ and ground or simply ground at terminal 85 with B+ at terminal 86. Terminal 30 is usually connected directly with battery voltage (B+) source for loads whereas terminal 87 establishes connection with ground side of this load through a load or simply it may be accompanied by other terminals like 87A, 87B, 87C etcetera for loading or grounding. Continuity through the relay control coil should be checked with an ohmmeter observing proper polarity during testing. The resistance should be the same irrespective of the polarity of the leads on the ohmmeter and for relays with a diode, higher resistance is recorded in forward direction of polarity. If infinite resistance is indicated on the ohmmeter in both directions, then change relays. Lastly, check for continuity between terminal 30 and 87 when relay is de-energized by removing the relay from the vehicle and using an ohmmeter to test continuity across its power circuit terminals; there should be no continuity between terminal 30 and 87 if it is healthy. On connecting fused jumper wires to terminals 86and 85, as well as positive battery terminal and ground correspondingly, relay makes a distinct click as soon as connections are established therein. In this configuration, terminals 30 and 87 should show continuity. If any of these tests fails, replace the relay.

There are so many electrical equipment fitted in the vehicle, which includes the fuel injection system, horns, starter and the fog lamps among others that use relay to in transmitting electrical signals to other components. Relays are controlled with an extremely small amount of current to open and close a large amount of power current, and if a relay is bad that means the related component will not work correctly. A vast majority of relays are installed in the engine compartment and interior fuse/relay boxes and if one believes that a certain relay is bad or failing, the relay should be removed and checked or taken to a dealer service department or auto electrical repair shop: in case of bad relays, these should be replaced as a package. These are mainly ISO relays which have digit symbols at their terminal to show their circuits and roles; they come in two types of terminal connection systems. The control circuit is usually connected to the relay coil whereas the other two terminals are connected to the power circuit. When energized the coil establishes a magnetic field that closes the large contacts of the power circuit to supply power to the loads. Terminals 85 and 86 are usually used in the control circuit but if a diode or resistor is incorporated then specific connections are necessary. Terminal 30 provides a connection to the battery voltage supply for the circuit loads and terminal 87 is connected to the ground side of the circuit. Using an ohmmeter one can check continuity through the control coil, and the must have the correct resistance figure in both directions: forward and backward, if the ohmmeter shows an infinite resistance, the relay should be replaced. When the relay is out, there should be no continuity between the power circuit terminals and there should be continuity only between terminal 30 and 87 when the MCB is de-energized. To check the relay the positive end of a fused jumper wire should be connected to terminal 86 and the negative end connected to the positive terminal of the battery while the other is connected to Terminal 85 to ground, the relay should click, and there should be continuity between terminal 30 & 87. In case of any test, which reveals that the relay has not worked, then such a relay has to be replaced.

Several electrical accessories in the vehicle, including the fuel injection system, horns, starter, and fog lamps, utilize relays to transmit electrical signals to the components.

In a relay, terminals 30 are typically linked to the battery voltage (B+) source for circuit loads, while terminal 87 connects to the ground side of the circuit, either directly or through a load. Additional terminals like 87A, 87B, 87C, and so on may also be present for load or ground connections.