The voltage in my 1997 CRV is pulsing (all lights dim and brighten and heater fan changes speed). There are no error codes, the battery and alternator check out fine. Watching the alternator output it is clear it is being told to increase and decrease output. When idling if all electrical loads are turned on the pulsing stops (the alternator stays on full and steady).

If the ELD was dead there would be an error code wouldn't there?

What else should I be checking?