I'm at work right now and just talked to a mechanic workmate, he said that the best way is get the reading tonight, also get a new battery, it is 8 years old anyway, only the reading can tell where the problem comes from
Thanks Salim, so I will take a few readings and post up here tomorrow ;)
I never use voltmeter before, that's why I don't know where the pins from the meter should connect to, or just touch the metal part would be ok........I'm so daft about this :(