1. Two of the relay pins must be connected by coils to control the contact switches of other pins; use the ohm range of the multimeter to measure each pin of the relay and the two with resistance. The feet are the coils. The coil should have a very small resistance when measured. If the resistance is infinite, it means the coil is open and the relay is damaged.

2. If you cannot find the two pins with resistance, it means that the coil of the relay is burned out and it is bad. The resistance of a relay is generally tens to hundreds of ohms. If the multimeter displays the overflow symbol "1", it means that the coil is open.

3. Measure the normally closed and normally open contacts of the relay. The resistance values ??are respectively: the normally closed contact is close to zero (below 1 ohm) and the normally open contact has infinite resistance.

4. It depends on whether the relay can be pushed manually to the pull-in part. If it can be pushed, keep the pull-in part of the relay in the activated state, and then measure whether the normally closed and normally open contacts are The status is swapped.