A test light? Have not used one in years. Hook the clip up to a ground, and then poke the sharp end in there where you wanna test. If I remember right there are only two wires there, just jab the fucker in there and see if one is hot. It should have battery voltage with the key on and car off.Nope, I haven't checked that!
I looked through my tools, I got a 6-12V Circuit tester; It's like a screw driver that lights up lol.
Well how could I check it for electricity using that? Also their are 2 cables coming into the plug, which one would I need to test.
Also that code isn't keeping you in closed loop, I threw my evap system in the trash a long time ago, car runs fine.