I had a tail light problem that the local dealer traced to the trailer
lighting circuit. The power for the trailer circuit had been spliced
directly into the power to the tail lights on one side. This, they said, was
a no-no with a Volvo hitch as it requires a "control module" which is then
wired into the fuse box at the side of the rear storage compartment.
The hitch had been installed by a Volvo dealer in another city, so if the
control module story is accurate, then I got shafted by the installing
dealer.
I would appreciate hearing from anyone with knowledge of the technicalities
of trailer hitch installation on Volvos.

Thanks,
Gerry