Electrical gremlins in the XJ

To start.....2001 XJ with the factory 4.0 in it.

Started it up today just fine. Drove it about 30 minutes and shut it off. Tried to start it back up and it was dead....completely. No lights, no radio, no nothing.

Popped the hood and twisted the negative battery cable at the terminal to confirm contact. It had contact and was tight, as did/was the positive. Moving it must have done something becuase it started up.

Left it running for about another 45 minutes at low speeds and idle (I was in line at the metal recyclers). When I got on the highway to go home the "check guages" light came on and the volt meter pegged at 19. I got it home, shut it down in my driveway and it won't start again. Even fooling with the cables hasn't helped.

FYI....it has done that won't start bit before, and jiggling the wires always made it start. That is how I knew to start it the first time it died today. This is the first time it pegged the guage though.

Any thoughts at all????

I've had the same problem before. A good cleaning of the cables and battery posts always worked for me. I tend to clean them once a month, and carry a battery cable and post cleaner in my Jeep.

I X2 SgtZipperhead....clean and TIGHTEN the battery connections. You shouldn't be able to move them to "reseat" them to get a better connnection. They should be TIGHT. Also, follow those main leads (power and ground) and clean/tighten where they go.

Sounds to me like you have loose connections. XJ's are sensitive to less-than-ideal grounds!

had same problem the other day. Including the volt meter maxing out. One of my crimps for a ground on my wiring mains upgrade had come loose (oops) easy fix.. But then no start? Didn't take long to figure out my quick disconnect to my positive ( used to quickly dis or connect winch)
that is basically two peices with a big screw knob to sanwich the batt terninal side weren't transferring current.. So upon disassembly noticed dirt all in between connections.. That's when I remembered burying it up to the hood about a month ago guess the muddy water left that dirt there and just now caused an issue.. Anyway a quick sanding (no contact cleaner in jeep) and VOILA! Only broke down for like 10 mins.. Most of that time wasted in initial confusion at my usually well maintained smooth running vehicle just not running out of the blue.. Guess I couldve just said CLEAN ALL contacts lol.
I bought connection cleaner and connection protector? I forgot but it's a spray on red film that covers connections

and like the other guys said I tighten all connections until I can't move by hand.

This is almost assuredly either a connection issue or a ground issue. Concentrate on battery cables AND engine grounds. Engine grounds are waaaay too often ignored. Here's more.
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Grounds can be the root cause of many electrical gremlins. Refreshing grounds is NEVER a bad idea!

You can't just check or look at these grounds. You must remove, scrape, clean until shiny the cable/wire ends and whatever they bolt to. The one on the back corner of the head, and where it attaches to the firewall. Scrape the paint from the firewall. Best to replace that woven cable with a #4 or #2 gauge cable. You can attach the one end to the intake manifold if you would like.

Next go over to the engine dipstick tube stud. Remove the nut and clean the wire ends and scrape the block until shiny at the stud. Reattach tightly.

If you are so inclined, add at least a #6 cable from the negative terminal of your battery to one of the bolts on your radiator support. Scrape the paint off first.