I've posted about this before, but have so far struck out. My 02 Impala LS gets into this mode every so often where the headlights/dashlights will blink on and off continuously (about 1 blink/second) when I decelerate.
The dealership has given me the standard line about it being the AIR pump and this is considered normal. I can live with an occasional momentary dimming, but that's not what happens. When this happens, the lights blink continuously until I either step on the gas or come to a complete stop.
I found this page:
Thanks!