Relay ID

I am extremely on basic when it comes to wiring , which one of the reasons that I am really happy to have taken this course . Would like to ask the following although how do I identify a relay that has no pattern on the outside nor any details on the bottom (even at the bottom if there are numbers it doesn't show you the configuration neither the amps )

If there is no diagram at all that can make things a little difficult. Although with a multimeter you should be able to test and find the windings and also the switch fairly easy. The switch in and out will be the 2 pins which have no continuity to any other pins and the windings will have resistance over the 2. If it a 5 pin relay you will find the 2 output pins are joined, or if its change over relay you will find 2 pins will have continuity but not with the 3rd.

To make life easier, if it has number then 87 (and 87a if fitted) are output to your Auxiliary/motor, 30 is power in, 85 and 86 are your switch/windings/exciter.

Thank you Chris for the info .