outside PIR light acting odd/sparky advice?

positivelymummy

when we moved into property there was an outside PIR light on garage, and we noticed it was wired to lead and it had been plugged into a socket inside the garage, i tried it and it didn't work although OH said it did work when he tried it....anyway....forgot all about it, i tried it last night and it did come on, stayed on for a minute then worked as a proper motion sensor light....for about half an hour:cool:

i'm sure i could hear the clicking when i walked by it, but no light...this is what OH said happened on the nights he tried it last year.....so its not the bulb as it came on again when i tried???

any ideas why this is happening,????