On the two solid gray wires...(use a test light and clip the ground wire from the test light to a good ground, then touch tip of the test light the to a gray wire) Turn on your lights and adjust the dimmer..... if your test light fades, then that is the power dimmer. If it does not fade then the wire is for the change oil indicator and the other gray wire is the light dimmer. You can then hook them up accordingly.