I was cruising on the highway, and ALL the power went out - headlights, dash lights, audio, display. Just for a fraction of a second. Nothing "rebooted", the music (I was using CarPlay over UAD) pickedback up where it left off and the car really didn't miss a beat. Anyone else ever experience something like this? I see no way to diagnose such a quick flicker of power.

 

I experienced a similar outage in my Toyota minivan about 8 months ago. It was on the interstate, doing the speed limit, 70MPH.
Toward the end of a 1.5 Hr, non-stop trip. Half tank of fuel. No issues since. Strange.

 

I experienced the same may 4-5 months ago in my 16R. Thankfully there has been no recurrence in the thousands of miles I have driven since then.

 

Not good. Happened again on the way home today. But this time it was longer (still under a second, though). The radio rebooted, the transmission gave me a flashing D and would not go in to gear until I stopped. The cluster knew it was running still, as the miles travelled would normally reset to 0 and they did not. Once stopped I could go to P and then to D and all was "well" again for the rest of the drive. But now I'm worried when it will happen next...

 

The only time that happened to me the cause was a loose connection at the battery. I found that by wiggling the cables in the trunk. Once properly tightened it never recurred.

 

My 2015 did something similar but from a start. Got in the car and nothing was on and the start button did nothing. Up to this point everything was running good. I opened and closed the door and everything came to life as usual. Def one of the Jag mysteries.

 

Please check the battery, usually the ground connection is loose.

 

The battery or ground connections was my first thought too…

 

hmmmm....I noticed this last week. I've only had this car a couple weeks now. I'll check battery grounds.

 

And the battery connections!

 

I wanted to close out this thread. After about 4 weeks of things getting worse and worse, I finally arrived to a dead battery at 3.5 volts and it would not take a charge. I got a new battery, and everything has been fine since. I suspect I was getting an internal disconnect in the battery causing my issues.

 

Thanks for reporting. Once again an experience that *might* indicate a serious issue has been traced to a very, very minor issue (minor in the sense that it is not an inherent issue with the car and it is easily solved). This can happen to a Bentley, Rolls, or any of supposedly faultless German makes too.
Did you fully charge the new battery before or at installation?

 

I bought a CTEK to go with the new battery, yes it's fully charged now.