THIS MAY APPLY TO SOME OTHER REPORTS HERE.
Cold weather increases electrical resistance.
Keys that work when warm, and don't work when cold? May be the same problem as this.
My car: 2005 Focus, 3 button type 2 key remote.
Having seen some weird answers to this problem of the remote locking not working, I've sorted mine out, and it is now as good as new.
FORGET about "static electricity" in the control box, and other such suggestions. Rubbish!
As an ex electronics engineer, I asked myself "why should it degrade in range, and then simply give up altogether"?
SIMPLE.......insufficient, or no battery voltage to operate the electronic key module properly.
But I've put in a NEW battery! I hear you say. So what?
The problem is:-
The condition of the battery contacts to the electronic module, get tarnished by age and dirt.
The electronic module draws such LITTLE current, that it can't break through this tarnish, and so it has, in effect, no battery to supply it.
Luckily, I've seen this problem before on other circuits, and seems a very prone to occuring on small signal relays etc, even though the circuit is otherwise FULLY functional.
Clean the battery connections!
BUT BUT BUT BUTTTTT......
The pads on the electronic module PCB in one half of the key, have a thin gold plating.......rub them very gently with an alcohol soaked tissue, DO NOT use anything abrasive. Finally, do the same with the battery connections, both sides of the battery, the battery to the built in contacts, and the built in contacts, to the remote module.
SORTED!
OH.....and when you have cleaned the contacts, you will need to reprogramme the key......30 second job, as mentioned above.
Insert key in ignition, and start at position 1.
Turn key to position 2 (Ign ON), and then back to position 1, doing so four times in less than six seconds, and remove the key from the ignition.
You will hear a beep from the system to indicate programming mode.
Press any button on the remote, and the system will beep again, to indicate acceptance.
WAIT 20 seconds before operating ignition or door locks while it closes "programming" mode.
NOTE: People suffering other problems have my sympathy, but these are almost certainly due to component / installation failure.
Faulty mechanism blowing fuse 63, one lock failing, but not blowing the fuse, etc etc etc.
That one about "remote locking" self operating is weird though. My guess is there is a faulty earth somewhere in the circuit, and the mechanism is being operated by electrical noise, or, the remote key is so worn and tired, that it's possible to operated it just by knocking the fob etc.
Replace the key? Easy but pricy......faulty earth connection? Good luck!
