When I hear complaints of widespread electrical hooliganism like this I
immediately think of grounds and especially the ground for the engine block
to the chassis.

Different cars have different ways of grounding the engine, but every engine
must be well grounded. The two general ways of doing this are to bring two
heavy wires out of the battery negative terminal, with one going to the
chassis nearby and one going to the engine block, and the other way is with
a separate heavy wire between the the block and the chassis. Seek and ye
shall likely find whichever one you have. Unfasten, clean and tighten each
connection point on general principals.

The other likely possibility is that the alternator or battery is causing
the battery voltage to be unclean when the engine is running. If it is the
alternator - bad diodes will do that - a measurement across the battery with
the engine running will reveal more than 1/2 volt AC on a digital multimeter
(you can't use most analog multimeters because of the DC component). If the
alternator is good, you will see less than 1/10 volt AC and about 14 volts
DC across the battery. Battery trouble doing that really isn't common, and
the only time I had it happen to me the battery refused to start the car
afterward.

Mike

-------------------------------

If the 'D' light is flashing, you probably need to put new tranny fluid
in your auto. (twice). If the cruise is dropping out, call the dealer
and see if they recommend changing the ignition switch. Ours started
dropping the cruise when it failed (97 CR-v) and Honda recalled about a
BILLION of them in North America. See if the dealer can get you an
owner's manual too. If not, eBay is a good place, or call around to the
wreckers.

The grounding wires idea is excellent too.

'Curly'

snip

How old is your battery?