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..

The hoses on the washer motors are swapped, or the wiring plugs are swapped. Swap the hoses on the pumps.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

That sounds good. I put them back on how they were, but since the washer system was not working when I got it (new bottle, new pump, new lid, nozzles from a wrecking yard), don't know what the prior owner did. The electrical connector can only go on one way and the hoses are bent for the way they are on now. Just looked and it seems I should have enough length to switch them...

A bit busy now and its snowing but should be able to get to it later and let you know how it goes... Thanks....

a freind of mine bought a BMW X5 2005 year, it had both pumps blown, we redid the entire washer tank, pumps, filter grommets etc. And swapped the hoses, the result was exactly like yours.

After swapping them around it was back to normal.

btw - if you break an elbow that connects the main heated hose to the hood nozzle - dont worry when you find its a part that mercedes no longer sells. BMW/mini use the same supplier and use the exact same part and sell it for about 4 dollars.

If the hoses are prebent and are correct then the wiring is wrong, that is also easy to repair, you might need to check for cuts/repairs on the ends, If generic pumps were installed in the past the wiring would be chopped and repaired. If all else is good then just redo the wiring connectors if you think the hoses are correctly routed.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

Ok, I checked the wiring and it has never been spliced. I however did buy an after market pump and it looked liked the original Mercedes pump that was still installed. Had trouble finding the pump for the wagon so bought what I could find (had never bought that brand of anything before). If the problem is that simple I can switch the wires or just buy a pump from Mercedes. Don't mind spending the money at the dealer if that's what I have to do.

I did break the elbow when I first took everything out, but when I got the nozzles from the wrecker I took the T-connectors and plugged one side with a vacuum plug and a zip tie, works well. However now that I know, I will get the correct part.

Thanks again for the assistance, I was afraid of just switching the hoses if there was an electrical issue that would remain and then jump up later. Strange that the pump would have have a different wiring system than Mercedes, but I have had after market stuff not fit before... Thanks again..

Found an official Mercedes pump and an elbow connector. I should be all good now, thank you very much for your time and effort....