So... my new to me LR4 is perfect or says my mechanic... however the ONLY key has stopped working. Well I can get the truck started thru the back up system, but will not lock or unlock. I have changed the battery. any ideas. I am headed to the Stealership in the morning but thought I would ask her in hopes by the AM someone sends along a message that helps me solve this before I go get robbed. And yes I am also ordering a second key. Argh.....

 

Which battery? Key fob or car? A seal of undercharged car battery can cause all sorts of electrical gremlins

Did the key fob ever work while you had it?

Sometimes the battery contacts inside the fob get bent and you can bend them back to make a better contact with the battery. Hate to ask but are you 100pc sure it's the right way around...

Also did you buy a cheap eBay one from China? They are often counterfeit and many don't work. I learned that the hard way

 

Its the key fob.. aka smartkey. I have gone to the stealership. we went thru it all as well. they also tried a new battery and looked the contacts. She is dead. New one ordered. Yes the Key fob worked.. then it did not. I was told the this happens. which I why its best to have 2 keys. Lesson learned.