Hi quick question anyone tell me this button on the left is for ,2010 plate .no handbook in unit its next to exhaust brake switch ,
If I remember rightly its a switch to cut the emissions from the exhaust for if you are loading indoors I believe.
Think it’s the white smoke limiter switch.
Yes def white smoke limiter I think you use it first thing in morning if its been sat all night.
Thanks for replies lads I was thinking along them lines,but not certain .
Turbo boost 
It could bloody do with a boost alright