I recently found it more convenient to use my spare key fob, unused for ten years. After putting in a new battery I found that while it will still start the car, the lock, rear latch, and alarm functions are nonfunctional. Putting it in the dashboard depression is no help. Since JLR deems these worth their weight in gold, does anyone have any suggestions for troubleshooting or repair? It has never been out of a climate-controlled drawer. Thanks, I hope.

 

The easiest first thing to try would be another new name brand battery. Not all batteries are created equal. I think there are some posts on here that list what the voltage of a good battery should be.

Beyond that you might try pressing each button a few times. The contacts could be a bit oxidized/dirty from non-use. After that maybe try some contact cleaner on the button contacts.

 

As cpq100 recommended, your first troubleshooting step should be a new key fob battery. When my fob was acting funny, it measured 2.88V. New Energizer CR2032 measured 3.33V for comparison.

It would still be able to unlock the door handle and start the car, but all buttons were unresponsive. Sounds a lot like what you're experiencing.

If a new fob battery doesn't resolve the issue, then check your vehicle battery. Make sure it has sufficient voltage and/or fully charged. If not, then replace your battery.

If either of those don't resolve the issue, I've read some that have had their RF Radio Receiver firmware updated by the dealer resolve similar issues.

Good luck!

 

Easiest first pass would be to swap the batteries between the fobs to see if the problem is in the battery or the fob.