Electrical - systemwide power flickers/surges

This is regarding a 93 XJ.

When driving along, the power will "flicker", for example, the radio will cut out if it's on, kind of like a CD skipping, and the voltmeter gauge on the dash will bounce a little. If the headlights are on at night, they will flicker, just for an instant they will get brighter than normal, dimmer than normal, then go back to normal. I just swapped out the alternator since that seemed like a good thing to try, no luck. I then cleaned the ground connections, and that did not result in any change either.

I tried a search and it almost sounded like a couple of other people had the same problem, but ended up being things like headlight switch, etc. I don't think that is my problem since this problem persists whether headlights or fan or whatever is on or off. However, nothing flickers if I have the lights on without the vehicle running (just running off battery power), but it still will flicker if the truck is sitting in park idling.

Could this be a voltage regulator issue? Or am I needing to start going through all the connections on this thing? If the latter is true, could someone give me a quick run down of connections to check (or just post a link if someone's done a write-up)? And this may sound weird, but I am not sure where the voltage regulator is or what it looks like. Is it the little module that bolts onto the back of the alternator?

Any help would be appreciated!

Check your battery cables and ground attachment points. I had the same issues. I installed new cables and added another ground point to the body. My problem is gone...

try another battery, regardless of just how superb you think yours is. An internal short can cause this kind of stuff. Other than that check the ground that runs from the neg terminal to the body. Also clean, or replace the terminals, and don't forget to clean the wires you're going to clamp.

If you decide that new cables are needed then try Kelleys Works in Progress to get your new cables from. His stuff is the best you can buy. He has kits set up for just about every imaginable applcation.