cant get windscreen washers working on mk 2 8 valver , have checked fuse its fine and checked pump direct on battery abd for good measure tried a new one , have 12 voltb there when put ba multimeter in the conectors and opperate the stalk . also if i take the connectors off the pump and pull the stalk the wipers come on as you would expect when cleaning the screen but when i plug thge pump in they dont come on weird .... please help as the dead flies are starting to build up