Front Fog light problem

Hi All

I hope someone can help withn this one as my local RR specialist is beaten. I came home after a few days away to find my RR nattery was flat. I disconnected the + terminal to charge it (now know I should have removed the -). After I charged the battery and reconnected, the front NS fog light decided to come on, on its own (even with the ignition switched off. I have removed the light and unplugged and re connected but the problem is still there. THe battery still isn't great and I will have to replace it.

Has anyone come across this and give me a solution? Many thanks

A lot of things can happen when the battery is disconnected no matter which cable you take off, the Becm under the drivers seat like a fully charged battery ALL the time and as you say "your battery is not that good" id sugest replacing it with new, makes sense as Christmas is comming bad weather and all that comes with it. not too sure as the the fog light but i would say 9/10 times this is related to the poor battery and the disconnection of the battery a while ago. it may well right it's self after a run round and a few presses of the switch.

Electrically, it doesn't matter one iota which lead you disconnect first. The recommended way is to disconnect the -ve first as that's the earth. The reason for this is to minimise the risk of the spanner you're using shorting across to earth (the body, not the -ve battery terminal) and causing a spark. If the -ve is already removed, you won't get a spark if you do inadvertently touch the body with the spanner. In other words, it's for safety reasons, not electrical.

With any BeCM problem, the first thing to check is the battery and if it's suspect, renew it. If yours is a petrol, I'd recommend getting a diesel spec battery. Bigger and more reserve.

Thanks for your advices. I will replace the battery and update you on the position

For all those who may experience this same problem in the future, fitting a new battery solve the problem of the self illuminating fog light. THanks Dougdotcom and Derek Ward for your help. Cheers