Checking switching devices
When the corresponding consumer is switched on, the relay is activated, i.e. under the influence of the control current, the electromagnet inside the relay closes the working contacts through which the main current passes to the consumer.
The easiest way to check the relay is to replace it with a known good one. That's what they usually do in the workshop. Since the car is often deprived of this possibility, the following test procedure is recommended for switching relays. The following relay contact designations are standard, but may sometimes differ. О Pull the relay out of its socket.
Turn on the ignition and the appropriate switch. О First check with a voltmeter whether voltage is applied to terminal 30 (+) in the relay socket. To do this, connect the wires of the voltmeter to «weight» and with the specified contact. If there is no voltage, check the voltage supply from the positive battery terminal to terminal 30 in the relay socket in accordance with the wiring diagrams.
Make a jumper from a piece of insulated wire, stripping both ends.
Using a jumper, close contact 30 in the relay socket (it is powered by battery) and output contact from the relay (usually denoted 87). Thus, the operation of a working relay is simulated. The pin number designations are usually found on the relay or on its socket.
If, when the contacts are closed with a jumper, the consumer has earned (e.g. headlights), it means that the relay is faulty.
If the consumer does not work, then you need to find out if he is well connected to «weight». Then you need to check the voltage supply circuit from terminal 87 in the socket to the consumer.
Replace relay if necessary.
Caution: If a fault occurs intermittently in the voltage supply circuit, then this is usually due to a fault in the relay, i.e. its contacts close normally while the relay is operating normally. If the relay fails, you need to knock on its case. If the relay works normally, then it needs to be replaced.