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Windshield washer pump pumps each time the wiper wipes


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OK, so I'm stumped. My recently purchased 1975 had the washer bottle and pump removed from the drivers side firewall when a prior owner installed a Tii engine, Top End Performance brace and air filter kit. I found the original round bottle and pump in a box of parts that came with the car. After cleaning the pump it works fine. The bottle leaked, so I replaced it with a new square one. Bought a washer bottle mounting bracket (thanks Jason Gipson!) and remounted the bottle pump assembly on the passenger front engine bay (see photo).

I've been trying to figure out where to wire the pump so it works properly. There are 5 wires coming from the pump motor. The wiper motor looks newish so I suspect it's a replacement. (see photo) and may have a different wiring harness. I've tried splicing the pump motor into each of thoe 5 wires (see photo). One of the wires activates the washer pump when pulling back the wiper stalk. However, the washer pump is also activated when I turn on the windshield wipers in any mode. I've tried each of the 5 wires, and none just activate the pump / washer without it also activating in other wiper modes.

I've looked at the schematic diagram. My former BMW mechanic friend has looked at it. Both of us are ready to just run a dedicated washer switch into the cabin.

Before giving up, I figures I'd see if anyone can answer the mystery. Is there a relay or something else that was removed from the car that I'm missing?




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Neither wire goes to the five wire wiper motor harness.

The Violet/Black (hot) wire should run to fuse #5.

The Brown/Black (ground) wire should run to the wiper relay under the dash and on to pin#3 of the wiper stalk connector.

Pulling the wiper stalk should ground the pump circuit and trigger the wiper relay to activate the wipers briefly.

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Thanks Jerzy,

That's a big help and confirms my suspicion that another relay was involved. Any tips on the best way to reach that relay up in the dash? Is it usually up behind the instrument cluster or behind the center console? Is there a part number for the relay in case a prior owner removed it and I need to replace?

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handle and is the larger of the two relays there--it's usually marked "Wisch-Wash-Geber". The other relay near there is for the turn signals.

Once you get the proper wire(s) connected, if the wash/wipe feature is not working properly, carefully remove the cover,look for burn marks on the little circuit board, and look at the set of relay points to see if they're burned, stuck open or stuck closed. You can often repair the relay with a little patience and some fine sandpaper to work between the points.


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- the pump turns on via the steering column wiper stalk.

It seems like you have the relay (your wipers work) and you have 12 volts going to the pump. You need to re-establish the correct ground connection from the pump to the wiper stalk.

The wiper relay is reached from under the driver's side of the dash. I don't know the part# - the relay says something like " Wisch-Wash" on it. (Try SEARCH for more info.)

Follow the yellow line in these drawings to see the pump to stalk connection that should be made. (*40 is the fluid pump; #50 the wiper relay; #56 is the wiper stalk connector; and #57 is the wiper stalk switch.)


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