I've been noticing the last few weeks while driving at night my headlights and instrument panel are dimming in and out. It seems to effect the AC too. I can't notice anything triggering it (bumps, turning, etc). Any ideas?
Loose battery terminals is the first thing that comes to mind. You can use the electronic odometer trick to find battery voltage and alternator voltage while the vehicle is running. Directions on how to use that are located in our How-To Archive in the dark blue banner above.
Check the wires that run into the alternator. Those have been known to fail. The odometer trick will let you know if you are under/over charging on the alternator.
If your alternator is at fault, please avoid grabbing a reman from Advanced/Auto Zone/Pep Boys/ Major Chain. They end up failing more often than not. Take a look in the phone book for a local rebuilder. It will be cheaper, last longer, and keep a local guy in business.
im having the same problem, even so far as to not start on occasion, and it all turned out to be that cable (red) from the batt along the driver side of the block, around the back and to the alternator had melted due to me putting a new terminal on the red side and it now has too much slack.