Checking the relay (Mondeo 1)

Many electrical circuits have a relay. A switching relay works like a switch. Example: if the high beam headlights are turned on using a manual switch, the relay receives a command to switch the current to the high beam headlights. Of course, the current could also be supplied directly from the battery, via the light switch. But all components with high current consumption (high beam headlight, windshield wiper, fog light) have a relay connected to the circuit so as not to overload the switch, providing shorter current paths. Next to these combination relays, there are also functional relays, for example, for the windshield wiper and washer systems or a warning sound relay for the external lighting.

Checking the switching relay

When the lighting element is switched on, the relay is activated, i.e., with the help of the switching current, the electromagnetic coil pulls the relay contact inward and thus closes the electric circuit of the "working current". The working current goes further to the consumer through the relay. The easiest way to check the functionality of the relay is to replace it with a working one. This is what they do even in the auto repair shop. Since the car owner rarely has a new relay at his disposal right away, then in such cases it is recommended to carry out the following operation in the case of so-called switching relays, which are used, among other things, to switch on fog lights and main lights. The marking of the terminals indicated here, especially for serially installed relays, can be presented differently.



Remove the relay from the holder.

Turn on the ignition and the corresponding switch.

First, use a voltage indicator to determine whether voltage is supplied to terminal 30 (+) in the relay holder. To do this, connect the voltage indicator to the housing (-), and carefully insert the other contact into terminal 30. If the LED flashes, there is voltage. If the voltage indicator does not show voltage, then use the circuit diagram to find a break in the wire running from the positive pole of the battery (+) to terminal 30.

Make a conductive jumper from a piece of insulated wire, stripping it until shiny.

By means of this jumper in the relay holder, connect terminal 30 (+) of the storage battery (always be under voltage) to the output of the closing contact on terminal 87. By means of this working operation, practically the same thing is performed as when installing a working relay.

If, for example, the high beam lights up with a jumper, then it can be assumed that the relay is faulty.

If the high beam does not light, find out if the connection to the housing at the headlights is OK. In this case, find and eliminate the break in the line from terminal 87 to the main headlight using the wiring diagram.

If necessary, install a new relay.

Attention! If a defect in an electrical circuit equipped with one relay appears only periodically, then in this case, as a rule, the fault lies in the relay: the contact in the relay disappears or the contact sticks too much, while the relay functions normally the rest of the time. If a defect appears, lightly tap the relay housing. If the relay still switches, replace it.

(The original can be found on this resource: Fordbook.ru)