My wife complained today that her key fob quit locking the doors of her 2005 S-Type a couple of days ago. It will unlock the doors normally and pop the trunk normally, but I confirmed that it did indeed quit locking the doors as it should. Also tested my key fob, and all functions on my fob work just fine. That told me the problem was inside her fob, probably not her fob battery, and I suspected that the fob circuit board and all metal contacts simply needed a good but gentle cleaning....

So for the first time since I purchased this car in December 2008, I disassembled a key fob (hers). Once I had the shell in three pieces, I removed the very thin anti-static mat sitting on top of the circuit board, removed the single small Phillips screw holding the circuit board inside the shell, and removed the circuit board. Using only a clean Q-tip with no solvents of any kind, I gently wiped all of the contact points on the circuit board. I immediately saw that the Q-tip was removing a thin sheen of very green-colored grime build-up, especially around the contact point that controls the door lock function. I took my time and made sure that all contact points on the circuit board had been restored to their normal shiny metal condition. Before I re-installed the circuit board back into its shell, I went ahead and pulled the key fob battery, cleaned it with the Q-tip, then cleaned the battery contacts in the shell with the Q-tip. Once all the components inside the fob were bright and shiny again, I re-installed the circuit board, placed the anti-static mat over the circuit board again, and reassembled the key fob shell pieces....

Went outside with the freshly-cleaned key fob, tested it, and all functions are now normal again. Total time elapsed from the time my wife handed me her malfunctioning key fob until I had it fully functional again was maybe 20 minutes. All you need is a very small flat-edge screwdriver to pry the plastic shells apart and a very small Phillips screwdriver to remove the one screw that holds the circuit board in place....

Hope this information is able to help some of those who come here looking for advice concerning flaky key fobs. There's no question that these fobs are neither airtight nor watertight, and as the years pass, small amounts of grunge will inevitably build up inside. And as I just learned, it doesn't take much grunge build-up on the circuit board to begin disabling the various functions....

 

Thanks my key fob started acting crazy 3 days ago..when I hit lock button all the windows rolled down and doors unlocked. I had to my battery out because I suspected the buttons were stuck. I took it apart and sprayed windex on the nearest piece of cloth and gently wiped the circuit board. Like yours mine had the same green grudge build up. After I cleaned it and reconnected it to the battery, I havent had any more issues.

 

Nice one Jon! I don't know how I missed this thread.

In addition to checking and or removing the green corrosion, besure to check the tiny black nubs on the backside of the thumb pad (under the plastic cover).

On Joyces I have found the unlock nub to be worn down causing problems with the unlock features.

 

Rick,

Will you attempt to fix Joyce's current thumbpad somehow, or do you expect to eventually have to replace it with a new one? I wonder if the individual components within these fobs are available at the stores in the mall that specialize in high-end key fobs. Next time I'm at the mall (which is maybe once or twice a year), I'll have to remember to check on that....

 

I had found if I push the unlock thumb button a certain way it works. It does need to be replaced.

George has a few extras he has, I just need to "remind" him to send me one.

 

Thanks for the help everyone....followed your instructions and at "this moment" all is well with the key fob!