How can you tell if relays in fuse panel are good

They can be tested if pulled out. Know how a relay works? Relays have a power side and a coil side. When the coil side is energized from voltage applied to it, the electrical contacts on the power side close allowing power to pass through the relay from the power feed supply on to the part the relay controls.

To test one, you use jumper wires from the battery to the coil side. Usually will hear a click-showing the power side contacts did close. The relay will have a small diagram etched into it, showing which two or more terminals are for the coil side, and which other terminals are the power side. If more than four terminals, the diagram will show how all are tied into the relay. Jumper a positive wire to the coil side input terminal, and a negative to the coil output terminal. If you have a multi meter, check that the power side terminals show continuity when coil side is jumped. It should have continuity-relay is good. If no multi meter, but you can hear or feel a click when testing-probably good.
That's the only way to test relays. Another solution if you suspect a bad relay is to swap in a known good relay. When the relay is pulled out, a good idea to check if the power feed for the relay is present. Use a test light grounded to a screw or metal bracket, and probe all the terminals that relay plugs in to. One terminal should have power lighting the test light, verifying power feed is good. Most, if not all relays, have a power source that is hot at all times, but if you find no power on any terminal, turn the key to on and check again-that relay may only have power available when key is in on or run.
Good luck.