Curious if there are other methods besides using a circuit tester pen.
What would be your definitive method for testing if a relay is bad?
Look at the diagram on the relay. Find something that works with the same diagram. Switch them and see if the other thing stops working. In my years as a mechanic I’ve only come across main relays that have gone bad really. The other two burned out and you could smell them.
Swap it with another one if my quick check. He really there are a few of the same kind in the fuse box.
Find the specs on your specific relay and test it with a ohm meter.
Apply 12 volts to the coil and listen/feel for the click. Swap with a known good unit.
Click doesn’t mean it’s good. The contacts can be faulty. So even if you hear it working I would still swap it to be sure
If you have a good enough meter, you can test the resistance of the coil and e see if it is in spec.
Going to use a cheap multi meter and see.