Headlights and dash lights pulsing

When turning on lights and when switching from dim to bright the headlights and dash lights pulse at a rate of about 3-4 pulses per second. This also happens with less intensity when the brakes are applied or turn signals used. The pulsing usually diminishes or stops in a minute or so but it is taking longer lately. The car has been starting well in cold weather. I have checked all the battery grounds?