Hi Dave,
I was able to solve my problem. I was able to find a bad wire on the connector at the parking brake actuator. At first look it did not seem as the wire was interrupted but it had a slight green oxidation. When I disconnected the plug from the actuator and tried to clean the oxidation I saw that the wire insulation has been damaged and with time the oxidation has cut through the wire, completing an open circuit.
Fixing the wire was not enough to get rid of the dash light and the fault code in the system. It took me a long time with BMW's RHEINGOLD software to reset it.

Ves