What are the common problems with relays?
The main drawbacks are loose contacts, cracks in the contacts, or excessive size and position deviation. This will affect the contact reliability of the relay. The faults of contact components generally include contact overheating, wear, and welding.
Does it matter which way a relay is installed?
The orientation of the relays shouldn’t really matter. On the bottom of the relay you will see the numbers 85, 86, 87 & 30 marked. 85 & 86 are the terminals connected to the relay coil (the relay control circuit) and 87 & 30 are the terminals connected to the switch contacts (the relay load circuit).
Does polarity matter on a relay?
Yes, polarity in a DC relay will determine the magnetic field direction – but remember the solenoid / magnet is acting on a lump of iron. Not usually a magnet. So in general polarity is irrelevant.
How do you connect a relay to a battery?
Attach one spade connector to relay terminal 86 (coil +). Attach the other to relay terminal 85 (coil ground). Touch the 86 wire to the battery’s positive post, and the 85 wire to the battery’s negative post. Actually, unless the relay has a diode in it, it won’t matter if the polarity is switched; the electromagnet will be energized regardless.
What are some examples of problems with relays?
For example, on a horn, the problem is often in the spring-loaded plunger behind the steering wheel that touches the ring contact that grounds terminal 85. On the high current (load side), test that 12V is present on socket terminal 30, and that there is continuity between 87 and the device.
What does it mean when a relay does not click?
If you hear or feel the relay click, the relay and its wiring aren’t the problem. But if it’s not clicking, the problem could be in the relay itself or in the wiring.
What do you need to know about changeover relays?
If your relay is a SPDT “changeover” relay, you can independently monitor the change in continuity from 30 to 87 and then from 30 to 87a to verify the switch opening and closing for both of the high-current paths.