It is absolutely essential that DC return is isolated from the hull. There is no such thing as not practical. Failure here with
induce electrolytic corrosion throughout your boat as well as neighboring boats at your marina. There have been multiple threads
here on this very subject. Engine installations are the number one source of this fault by amateurs and professionals alike. Boats
are not automobiles and must not be wired in the same manner. The general cause is that many of these engine sensors use the
engine block as the DC return.
Steve

"goofball_star_dot_etal" wrote in message o.uk...
On 06/04/2010 21:33, goofball_star_dot_etal wrote:

In particular, check the integrity of the alternator earth path (since it seems that the error is associated with charging
current), the engine earth path (since, probably, the temperature sensor thermistor uses the engine as earth), and the
instrument earth (since that is where you see the problem). In an ideal world one would have a single point earth but this is
not always practical.