hi people i have a problem with me s2. lights go dim on dashboard and the battery drains to around 11v and starts running rough and the electric fan slows on coolant and engine starts to get hot it doesent do it all the time it comes and goes.i have checked the earths and they seem ok the owner before changed the alternator but still had the same problem i have put a new battery on the car can anybody come up with some more ideas and if possible can you guys tell me where your earths are on the engine bay so i can check this with mine.

thanks chaps.