Checking the relay (Mazda Familia BG)

Many current circuits have built-in relays. The switching relay works like a switch. For example: When the high beam is turned on via the manual switch, the relay receives a command to supply current to the high beam lamps. Of course, you can supply current from the battery to the lamps directly via the manual switch. All high-current consumers (high beam headlights, windscreen wipers, fog lights) relays are included to avoid overloading the switch and to ensure the shortest path for the current. In addition to such switching relays, there are also functional relays, such as for the windshield wiper system or the relay for the signal for switching on external lighting.

Checking switching relays

When the corresponding consumer is switched on, a control signal is sent to the relay, which means that the magnetic coil inside the relay pulls the contact and closes the "working current" circuit. The working current flows through the relay further to the consumer.

The easiest way to check the relay is to replace it with a known good one. This is what workshops do. Since hobbyists very rarely have a working spare relay, the next step is recommended with the so-called switching relay, which is used, among other things, to turn on the fog lights and headlights.

1. Remove the relay from the mount.

2. Turn on the ignition and the corresponding switch.

3. First, use a voltage indicator to determine whether voltage is applied to the corresponding positive terminal of the relay socket. To do this, connect the indicator to ground and carefully insert the other contact into the terminal. If the indicator LED lights up, voltage is applied. If the indicator shows no voltage, check the wiring for a break from the positive pole of the battery to the terminal according to the diagram.



4. Make a jumper from a piece of insulated wire, the ends should be stripped.

5. Connect this jumper in the relay socket to the positive terminal of the battery, which constantly conducts voltage to the relay output. This is almost the same as inserting a working relay. The location of the terminals in the relay socket can be determined by the colors of the cables in the diagram.

[The article is reprinted from the portal MazBook]

6. If, for example, the high beam lights up when the jumper is inserted, then the relay is faulty.

7. If the high beam does not light, determine whether the headlight connection to the ground is correct. Then check the wire from the relay terminal to the headlight for a break using the diagram.

8. If necessary, insert a new relay.