JimmyL,

You don't have to remove the GP, just the GP cable connector from the GP relay so you don't get parallel resistance measurements. That's what makes this test so easy and quick.
Do a search an Ohmeter and you should find the procedure.

THe GP light does not necessarily tell you the GP are on. Do this: Turn on cabin light. Turn key to run position, you should hear the GP relay click and notice if the light dims. If it dims, GP are heating. After about 45 seconds, the GP relay should click off and the cabin light should get brighter. If it does, it means the GP relay is working correctly and turned the GP off.

P E H