[dmjlambert]

Do you have a gauge cluster or warning light cluster?

When testing continuity between ground and the point on the printed circuit were the grey wire connects, are you using an alligator clip? I ask because I did that and realized when I got a short it was because bottom jaw of the alligator clip was clamped on the metal case of the cluster and top jaw on the printed circuit trace, which are normally kept separate with a thin sheet of plastic. So I started smoking my test wire. So, proceed with care.

You say you are getting continuity between the No. 8/grey wire terminal in the cluster plug and ground, I think that may be normal with the lights off. I can't really mix continuity tests and voltage tests without confusing myself, so I usually stick with one or the other. Testing for voltage present or not present relative to ground will check the circuit under load, which is usually better than continuity test that puts very little load on the wire.

How is the headlight switch turned when you are checking for voltage on the grey wire? It is a dimmer, so turn it all the way up, which is counter-clockwise.