When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
You need an ohms meter. You also need to know the specs for the coil. Once you have these all you need to do is connect the meter to the coil power and ground and read the ohms.
If you don't have an ohm meter then what I would suggest is getting a multimeter that way incase you need it to test other things such as ac/dc current