Trying to help my buddy with his 96 XJ6 with the AJ16. He has an electrical issue with the following symptoms.....Happens at idle and while driving. Voltage indicator drops to 9v, all the dash warning lights come on, then all gages drop to 0, and it acts like it is going to stall. Then a second later everything goes back to normal and runs fine. This happens every few seconds to a minute. Thinking it might have been generator related, he replaces the generator and battery but it is still acting the same. Have been searching everywhere and can't find these symptoms posted about anywhere. Any Help would be appreciated, I'm going over to his place tomorrow to dig deeper. Thanks!

 

Did he replace with a new fully charged battery would be my first question.

 

The connection between the battery and the engine bay goes through 3 studs on the firewall. These are know to get corroded and cause high resistance so worth a look. To find them, follow the main cables from the engine bay fuse boxes back to the firewall and from the starter back to the firewall.

Also check the engine earth strap which is down near the starter motor.

It's worth dismantling these connections for a proper check and clean rather than just eyeballing them.

 

He has one or more bad ignition coils. Delay your assist visit until this evening when it's dark.
Pull the coil cover and fire the car up in total darkness. Look for a very faint lightning show in the top of each of the 6 coils. (Sometimes they give this telltale sign but not always)
If no indications, start replacing them one-by-one. Caution, it may be more than one that's gone tango-uniform on him.

Note: Consult the thread on coils before purchasing any new ones. It may be in the stickies, but shouldn't be hard to find, if not. It has about a bazillion replies.

FWIW: There is plenty written here on it. First time I saw it was in a post by Motorcarman, in response to a thread where a member was at wit's end with similar symptoms. He was so frustrated that he followed Bob's advice even though it "Didn't make sense" and posted his profuse thanks immediately thereafter for the solution.

 

+1. I had to swap one on the side of the road early last year as it was doing exactly what OP described. Easy to check and swap.