I recently tried to drive my 2010 XK to find the battery completely dead. I spent 3 days with it on a battery recondition charger. It runs but all sorts of weird things are going on. First I had to press the foot brake and parking brake to stop constant chiming. Then it said Smart Key Battery Low. I replaced the battery with a new pack of 2032 I had ordered off of Amazon. I was able to drive it. Now it says Smart Key Not Recognized Insert in Slot. I finally found the slot and put the key fob in. After 3 or 4 times it started while we were out. Just now I have tried it again and it won't start even after a few attempts. Is there anything short of getting the BCM reprogrammed here? Thanks for your help!

 

Does the smart lock/unlock the doors - you might want to disconnect the battery to do a hard reset - make sure the battery is fully charged before reconnecting - how old is the battery? Old batteries cause all sorts of weird issues.

 

No, it didn't unlock or lock the doors. I haven't done a hard reset yet. I put the charger back on it. It read 90% 12.7 volts but I am topping it off. Battery is from November 2022.

 

Have your battery load tested at your local big box auto parts store for free. Longevity was compromised because it was totally dead. It might not be able to hold a charge now.

Or you can just let it sit for 2-3 days and then check the voltage if you have a multimeter. If less than 12.6V, replace it.

 

The memory used to persist the value of the fob is not volatile. Meaning there is no need for reprogramming.
What you will need to do is heed Stuart’s advice. (incidentally, a resting period (not connected to a charger) of 6 hours should do it).

 

Cheers

 

I gave it a rest after charging earlier this week. The key not recognized issue persisted. I drove it around for awhile to build up the battery but didn't want to go too far given that the key isn't being recognized.

This morning, I tested the battery and the capacity was 50% and the voltage was 12.3. I'm thinking I'd better replace the battery.

 

How can you drive it around if the key is not recognized?

 

I have to insert the key fob into the center console and so far it has let it start even though it doesn't recognize it till I do.

The error message is "Smart Key Not Recognized, insert Key Fob in Slot" or about those words.

 

Doesn't that suggest it's the smartkey battery that needs replacing?

 

It could…. or the antennae are not behaving. Codes would help.

 

I have replaced the key fob battery and the issue persists. I will look up codes for this. I appreciate all the help. The previous comments seemed to indicate the car battery was at fault as this is one of the errors that often occurs when the battery has been flat.

 

Some people use either a slightly thicker 2035 battery or a foil shim to better contact the prongs inside the smart key. Bending the prongs to press harder may cause them to break.
Evidently your key IS recognized by the car, just not transmitting far enough.

 

I took the liberty of ordering a new fob key back as one of the sources I had read suggested it might allow better contact.

 

I tried new Jaguar OEM key backs (the ones I had were generic). Neither key fob worked. Neither did they work with the battery that shipped with the Jaguar back. Would I add a little bit of foil onto the top of the fob battery facing the other piece for better connection? I'm rather afraid I might short something out. Maybe electrical tape under the fob battery as that might bring it closer without risking a bad electrical discharge.

 

The CR2035 battery is no longer available. It hasn't been made for years.

For security, Jaguar designed the Smartkey to have a short range to stop code grabbers who would then clone your key and steal your car. This was a problem with the X100 models. The X150 Smartkey is a digital vault coded to your instrument panel. That's like the bond between a parent and a child. And is why those keys are so expensive and difficult to program.

You can increase the range of your Smartkey by holding it against your forehead when you push the button. Your skull acts as an antenna and increases the range.

https://driver-safety.wonderhowto.com/how-to/quick-tip-pointing-your-car-remote-your-head-increases-its-range-0139966/



See these threads for everything you need to know about the Smartkey. Note that the advice about the CR2035 battery is no longer valid. Which type of Smartkey do you have? Learn about your Smartkey here:

Smartkey Fundamentals - Two Types, Not Interchangeable

Educate Me on Smartkeys

 

I suspect that Smartkey doesn't work because it isn't properly programmed. I assume that you have two Smartkeys, one that works and this one that doesn't. Try standing next to the driver's door, hold that key to the glass, and press the button. If nothing happens, either the battery is bad or the key isn't programmed. To make sure that the battery is good, simply swap it with the battery in your other Smartkey that works and see what happens.

To program a Jaguar X150 Smartkey, both of your Smartkeys must be present together with the car. Consider that to be like a wedding ceremony, where the keys are married to the car.

It used to be that only a Jaguar dealer could program Smartkeys, but that software has been available for years so that locksmiths, independent mechanics, and owners could do it.

 

Stuart, this is true for passive mode but not for active mode, yesno?

 

The way I took it, the only key he has needs to be inserted into the center console for him to use the car. He did state the key needs to be inserted. That would mean the key is programmed but does not transmit.
I guess I have to throw away those few 2035 batteries I still have, they are probably quite old if they are not made anymore. Well, ****. Guess I'm even older than I thought I was.

 

Based on reading those threads the XK is a 2010 and should have the dual frequency option. I learned a lot about the passive and active functions of the keys. Currently, neither fob starts the car remotely or locks/unlocks the door. When inserted in the console, one fob starts the car and the other doesn't. I put new batteries in both fobs with the same result. That sounds like probably one of the fobs is no longer programmed to the car, and the active parts of one fob are not working for whatever reason, or I bought a pack of dead 2032 batteries from Amazon. ( I also used the 2032 batteries on the OEM Jaguar backs that came yesterday and still neither car fob works in active mode, and one of the two works in passive mode (if I read that right.)

All this began when my car battery went completely flat due to not driving the car after my white Jag came back from the shop. Online videos show the fob key being corrected by using SDD (which I don't have, but want to get.) They also mention this happens often when the car battery has gone flat. I have not tried a hard reset yet, but I'm increasingly of the opinion that it may take a reprogramming using SDD to take effect. I've had some conflicting advice above as to whether I should replace the car battery. I truly appreciate the help!