I have a problem with my rear window defogger on a 745T. Just recently, it started operating intermittently. The light on the switch will come on briefly when first switched on, then click off in a minute or two and cannot be restarted. I have confirmed that the defogger works with the light on and stops working when the light goes out. Once the car has cooled, it will start working again. It seems to be worse when the temperature in the car is warm. If it is cold in the morning (< -15C) it will stay on until I get to work (10 minutes).

I suspect the control relay is the problem. My problem is the Haynes manual I have doesn't shed any light on the location of the relay. Before I get my hands scraped up trying to locate the relay, does anybody know where the thing is located? Any similar experience with this kind of problem?