[The Newell]

A relay is a switch, nothing more, it is usually operated remotely by another switch or controlling device.

There are several "Tests" that can be done on a relay, all that is required is a multi-range volt meter (or auto ranging one)

And a pair of eyes

First measure the voltage across the coil.. It helps here if you know what it is supposed to be and if it is supposed to be AC or DC (This info is often stamped or printed on the relay) If there is no control voltage.. The relay is NOT the problem.

IF there is control voltage.. did the relay pull in (Did the contacts change state) or not? If not, the relay IS the problem

NOTE: High power relays may move a little, but not pull in all the way.. That is a "Welded contact" condition.

Next we measure voltage across the contacts.. If the contact is supposed to be open, then the voltage should be whatever the voltage is there (NOTE: on AC relays used in auto transfer switches this can be misleading)

If the contact is supposed to be closed the voltage should be near zero.. as in .0x or .00x (If you can measure it it may well be too high)

In many cases, if the contact is not closing properly you can "Burnish" the contact. DO THIS WITH POWER REMOVED.

Now, that said relays come in both "Sealed/Enclosed" and Open frame types.. Open frame you can see the action, you can easily see what contact goes to what terminal

Enclosed (included sealed) you have to rely on the diagram printed on the case.... IF there is one.. Else you have to find it's "Data Sheet"

Some relays.. That can be a whole LOT of tests.

And... IF it is a 120 volt relay there is enough power there to be fatal.. So be very careful when running those tests.. Even 12 volt can cause you some serious discomfort (Like 3rd degree burns).