Thank you to everyone that helped me to resolve the mysterious problem
on my WestFalia.
All I had to do is change the X-contact relay and voila', the good part
is that it only cost $5.
Special thanks to SStones that wrote to me indicating that:
" if the rear defog switch light doesn't come on with the switch, then
definately suspect the load reduction relay"
this was the line that clear the up all of the enigma. I did not notice
that the defog was not working as well.

Aloha

Marco B.