Welcome to MA. It sounds Like you have probably done this but did you try unplugging the wiring harness from the back of the housing and plugging it back in to make sure it was seated? The only other thing did you put the multi meter on it to make sure it was getting 12v when the brake is pressed? If you don't have a Bentley manual you may want to get one they are very helpful. I am on the road but when I get home I will take a look and see if they have a good digram in ti.