Jamie57

2000 XJ Sport 4.0 4wd 2 dr. and while driving along on the way to work at 4 AM(That sucks first) but as I get on the highway and get up to about 70 mph the CHECK GUAGES light comes on. Whoa!!! What? Temp is fine Oil pressure is good. Ummm 19 VOLTS!!!!
Quick, pull over and then shut down Baby. try to restart her. Nothing. Try again and starts right back up.back to 13.8 volts.
She has done this 3 times in the year or so that I have owned her.
Going back to my days as a mechanic the only thing I could come up with was a bad negative at the battery. Check when I get to work. Nope still tight and corrosion free. Got a new battery when I bought her and changed the terminals to Marine brass one's right away.

I'm stumped

Sails

Could be bad grounds or alternator voltage regulater, I would hook a VOM up and see what it really is. Shouldn't be hard to rig a VOM in and the would show whether the voltage that is being reported in the dash is real or not.
I know that half my dash likes to play free games now and then with swings from one end to the other end of the dial, no reason that the voltage gauge couldn't do it by itself.
The nothing on the restart makes me lean towards a connection issue.
Just my nickel's worth!