I am also going to do a thermal test on the heater control valve pipes, input and output, when i have the heat turned on in the cabin. I also understand that if you disconnect the power plug to it the heater control valve defaults to open allowing hot water pass and also a voltage test on the plug will tell me if the signal is getting to the heater control valve as well. Some things to do.

By the way, for my model car e53 4.4i 2005 there is virtually nothing on the site or google that shows where the auxillary water pump is. I think I know why as I found one that said it is under the power steering resevoir which will be easier to see once the expansion tank is out.