I have tried the borrowed battery. When the battery is fitted in the car the volt readings are zero when the positive is taken off it has a volt reading. I have removed 1 wire at a time off the positive side and have found what wire seems to be the problem. Can someone tell me what the 3 + wires are that run behind the battery towards the fuse box are so I can try and find the problem. The wire that's causing the problem seen better days as I stripped back the plastics cover.