Just dismantling the above step to either repair or replace. Have managed to get the step off but can't work on it away from the van due to the cabling (see below) I can disconnect the + - red and black cables as there is a coupling but there is a thicker black wire and I don't know what its function is. Is it something to do with the automatic closure or is that the red/black cables? Some advice would be great. I'm thinking cut the thicker black cable then reconnect?