wrote:

From what you describe, the multisystem failure would tend to indicate
something in common. Possibly a shared breaker (avionics avionics
master), but most
likely a single-point, shared ground that's flakey.

Most GA aircraft are a multi-layered hodge-podge of crappy electrical
wiring.
In particular, grounds tend to be wherever the last boob to install it
had a pre-cut
wire long enough to reach. Having a single-point where everything
grounds is a good
thing to eliminate ground loops. Gotta make sure that one point is
solid, though.

Concur. Most likely it's not a short, which would pop a breaker. An
intermittent open or high resistance connection would fit the symptoms,
and the ground connections are the places to start looking.

--
Dan
C172RG at BFM