head light washers prob

[jme1981]

Hi all im a new member and im new to mercs so get ready for some daft questions. I have a w209 clk320 avantgarde 2003 and it has light washers fitted but i cant get them working are there any common probs with them i have already checked all the fuse's. the lights dim a little when i press the button so its not the switch

thanks in advance