Ok so I have a 2016 F Type S convertible. I went to drive the car several days ago after sitting for a week in the cold. It started but I got the "end of days" dash display and would not rev. The battery tester indicated the Battery was good but I charged overnight. The next morning it would not crank at all and still had the Griswold Christmas lights going. The tester recommended replacement this time.

I bought a new battery and based upon suggestions from this forum I charged the new one overnight. I tested it within minutes (of course it read high) and got "battery good" with 100% health and 13 volts charged

The alarm of course goes off when I install the battery and now neither fob will quiet it. I changed the battery in one fob and it worked this time. I can only turn on the ignition on occasion otherwise it does nothing when depressing the start button and of course it will not start. If I hold the start button down for a few seconds the dash displays "smart key not recognised, reposition or place as shown and press start button....nothing!
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I disconnected the neg terminal to reset and neither fob will work to turn off alarm. Reset again and fob turned off alarm. Key fob seems to work usually during this ordeal to open trunk. While sitting in the car I am able to control windows and the CLA has power. The red triangle of death turned off after checking 20 minutes later. armed. The battery now shows 100% health and 12.51 volts and "Good".

What in the world is going on with this thing?
I just checked the battery and voltage is up to 12.59 after resting from the light displays.

 

Any corrosion on the battery cable terminals?

 

None at all

 

Did you hold the key right up to the little indent under the dash when trying to start it?

 

I guess I’d lift out the trunk insert and check the ground cable’s connection to chassis, and the other connections in there.

 

I placed the fob just above the OBD port I do not recall an indention though.

 

That may be it. There is an indent for the key way on the left side, under the trunk release. It's not a huge indent or anything, but you should be able to feel/see it.

 

Sounds like a lot going on. You have fob issues. You have an alarm interfering. You have starting issues. You have Griswold lights? what exactly does it look like?

The fob message is because it doesn't detect your fob - usually fob battery issue.Try buying new batteries for both your fobs and replacing them - I know you replaced the battery in one, but was it new?

Starting issues and general electrical freakiness is often due to grounds - not just the nice clean protected grounds and battery terminals in your trunk. There are several - check the ground underneath the car attached to the transmission, as well as the ground in your wheel well (passenger or driver, they vary, can't remember why). Also one from your starter to the chassis. There may be more, these cars are complicated lol

 

I always check the voltage in "new" batteries before fitting them - I've been bitten in the past when allegedly new batteries were nowhere near their nominal voltage.

 

Make sure both battery cables on the battery you just installed are tight.

 

I found the indention but it did not seem to make a difference. The fob works some of the time then it will fail to do anything. Finally after pressing repeatedly it will lock or unlock...some of the time.

 

yes both are tight.

 

I'm beginning to wonder if my battery tester is having issues. These two pics depict back to back tests. Note the "good charging". There was nothing charging. Another thing is when tested the old battery the tester said to replace battery. I picked up a new battery and tested the old one while still installed and got "good battery".

Can all of this be happening at the same time? good grief!!

I replaced both fobs with new batteries as my battery stock had some "2024" batteries in there. No change at all they still work intermittently.

 

I hooked up my iCarsoft LR V3.0 when I was able to turn the ignition on. It showed I had 24 fault codes!! WTH?! I could clear any of them

 

Do you have a battery charger or maintainer? If so, charge the battery to 100%, then see if you still have issues.

 

The Jaguar documents I've seen (from some years ago) say you test a battery by fully charging it and then removing the surface charge before checking the voltage, which should then be above 12.5V. To remove the surface charge either leave the battery for 24 hours before measuring the voltage, or leave the headlights on for an hour, which apparently has the same effect. That advice predates LEDs, though, so may not be entirely accurate nowadays.

 

Decent point, you could pull the battery out and take it to a local autozone (or the like) to have them test it. Even then, we all do know these cars are finicky with battery charge and these AGM batteries are a little different than your typical ones. If this is the original Jaguar battery it is definitely overdue for replacement anyways - batteries don't last forever. You can get any equivalent, they all work fine.

 

On a previous XKR I was having intermittent electrical issues which I put down to a failing battery. I went to a local store to buy a new battery and the guy said he couldn't sell me one until he'd tested mine. Which he did and pronounced it as "fine" and refused to sell me a new one. So I went home and ordered a better battery cheaper on line, got it the next day and, once fitted, the car behaved perfectly again! Go figure. Way to go out of business, eh?

 

This battery was replaced a couple of days ago and I fully charged overnight with my ctek. No change with the car

while I was screwing around with the fobs I decided to try to start the car and the friggin thing started. As soon as it did the tach decided not to work. After about five minutes the entertainment center decided to come on but was not responsive to to any button pressing. Interior lights worked along with heated wheel (weird). The windows would roll up and down every so often.

i hooked up a charger and called it a day. I’ll disconnect in the am. I was finally able to arm the alarm after numerous attempts with both fobs and the door handle.

This is when it started

These are five minutes later

 

Next I'd confirm those grounds. Especially the one connected to the transmission middle of the car, get underneath and see if it's corroded.