Relay — general information and checking the correct functioning (Opel Corsa B)

General information

To supply power or control signal to some of the electrical consumers in the vehicle (such as fuel injection system components, horn, starter, cooling fan, fog lights, etc.) relays are used. In fact, a relay is an electric key that ensures the closure of the high-voltage circuit by a low-voltage signal. If a relay fails, the corresponding consumer will fail. Most relays are placed in mounting blocks located under the instrument panel and in the engine compartment of the car. A description of how to check the proper functioning of the relay is given below. Failed relays are subject to replacement.

Examination

If it is not possible to find out how to connect the relay to the corresponding electrical circuit using the electrical connection diagrams (see section Electrical connection diagrams), it should be remembered that the approach to testing any relay is, in principle, the same in all cases.

In most relays, the control circuit is always connected to two of the contact terminals. When low-voltage voltage is applied to these terminals, current begins to circulate through the relay control winding, resulting in the closure of the large contacts of the working circuit of the consumer of electrical energy. The remaining terminals are the terminals of the working (HV) circuit.

To facilitate identification of the relay terminals, explanatory markings with an image of the key connection diagram are usually applied to its body.







1. Before removing the relay, make sure that the corresponding circuit is de-energized.

2. Connect a fused jumper wire between one of the relay control terminals and the positive battery terminal. Use a second jumper wire to ground the other control terminal - the relay should click. Some relays require that the polarity of the connection be observed - if there is no click, try reversing the polarity of the control terminals.

3. With the jumper wires connected, check for conductivity between the terminals of the high-voltage circuit by connecting an ohmmeter in accordance with the key diagram on the relay body.

4. If the test result is negative, replace the relay.