Long story as short as possible

Focus st 2008, key fob started to stop working on the odd occasion. like after i had locked the car it wouldn't let me back in. Then whilst driving the key outside vehicle warning would flash up. after setting off the alarm numerous times and been locked out for up to 20 mins some times the dreaded trip to ford followed. 100 quid later, no faults were found, batteries swapped for brand new ones, fob program was checked along with antenna signal. all working fine. current issue still happening i locked the car with the fob, got in to it with the key and the interior light switch was on so i flicked it off and hey presto it recognized the key. flicking the switch from on(when you open doors) to off then back to middle works every single time the fob stops working it picks it up straight away.

Any clues would be great haha.
i cant figure it out for the life of me, and i hate locking the car with the key and then having to mess around once im in.
If anyone else has had problems similar tell me how it was fixed. Remember the fobs DO NOT need re-programming

Cheers

 

That's an odd one, never heard anything like that. Try an auto electrician, far more experienced and knowledgeable than an apprentice at the Ford main dealer.

Have you tried a different key?