New to Mercedes, I have a 2000 E320 wagon (100,300 miles) that I have been fixing up for the grand daughter. Lots wrong, but a very clean and smooth running car. When the wiper switch is turned on for the front the wipers work. When the spray button is pushed in hard the wipers continue to run but the rear window washers spray. When the same switch is pushed lightly I get one swipe but no spray. Using the center console switch for the wipers the rear wiper swipes and the LED light comes on. When I press the button for the rear water, the front windshield water sprays. The steering wheel switch functions properly in all other modes.

Brand new battery and all the fuses have been replaced. Battery was old and 3 fuses had been blown. I did not like how the washer pump relay (grn color drivers side engine compartment) tested so it was replaced (a method of testing would be appreciated - it was a strange relay to me). The washer pump was not working so that was replaced also. It is a single pump design and the electrical connection only goes on one way. Could the new pump be defective and how would I check it?

Any ideas on what is wrong and how do I test the pump or the center console rear window switch to see if something is not working? Is there some module that both the steering wheel switch and the center console switch go through?

I am out of ideas and this is the last item I need to fix.. Thanks for any assistance..