Washer Switch Hack

The windshield washer on the 1974 Porsche 914 is activated by pulling the wiper lever back toward the driver.  Nothing unusual here, except for how the fluid gets to the windshield.  Instead of engaging an electric pump, the fluid is routed directly through a mechanical valve in the column switch, propelled by air pressure from the spare tire!  This is common to many Porsche and VW cars of that period, and seems rather clunky and dubious by today’s standards.  What engineer would pipe water directly into the electrical clockworks of a steering column?  I decided to swap in a newer washer switch and electric pump, as described in a technical article on the Pelican Parts website.  It names the Porsche 924 wiper switch (part #111-953-519-G) as the one to get, but a Google search also locates the same part in the ’74 Karmann Ghia, and ’74 to ’79 Beetle.  Since I’d rather pay VW rather than Porsche prices, I ordered one.

Below is a comparison of the original washer/wiper column switch on the left with the new switch on the right, purchased from California Import Parts Ltd.  The new switch will include nozzles for the old-style hydraulic valve. These can be removed as long as the 6-pin version of the switch is purchased, which also contains the built-in contacts for the electrical washer pump.

As you can see, the new switch on the right has a slightly larger J-connector with two extra pins,  even though the column switch ring is nearly identical.  Those extra pins are attached to an electrical leaf contact switch that actuates when the wiper lever is pulled backwards.  Although the new J-connector will not fit into the existing steering column, it’s possible to swap the new wiper switch wires into the old connector.  To begin, I made a list of all the wire colors on both switches, what order they occupied in the wire guide sleeve, where they were attached to the switch ring, and then swapped them wire-for-wire.  The existing pin ends stay connected to the wires, and just slip right into the old J-connector.  If done correctly, two extra wires are left dangling that both come from the washer leaf switch in the switch assembly. Both of those wires will deliver 12 volts, but only one is needed, and can be routed down the sleeve and into that bottom empty pin slot in the original J-connector seen at top in the photo above.  The other wire should be clipped and capped.

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Here’s a close up of the wiper/washer switch.  The top of the leaf contact seen above (just under the two screws) is actually divided into a front and rear top leaf.  The black/white-striped wire in the top foreground is attached to the front upper leaf, and is seen running left to the guide sleeve.  The rear upper leaf is attached to the blue wire, which delivers power to the entire wiper circuit.  The lower contact leaf is attached to the brown wire, seen capped in the blurry background above.  When the wiper lever is pulled backward, the bottom leaf is forced upward to touch both the top leafs, putting all three wires in contact.  Power from the wiper circuit flows in on the blue wire, through the closed contacts, and out through both the brown and black/white wires.  As I said, only one feed wire is needed, so I capped off the brown one and used the black/white wire to power the pump.  I blew a string of wiper fuses before realizing that the front metal leaf attached to the black/white wire was actually shorting to the inside of the steering column!  Juice from the wiper circuit was jumping straight to ground every time I pulled the washer lever.

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My solution was to eliminate the short circuit by removing the top front leaf altogether, and using the rear contact instead.  In the above photo, the front top leaf is gone, and the bottom leaf with the brown wire is left intact.  Since I had earlier clipped the contact pin off the brown wire, I replaced it with the remaining black/white wire pin.  The brown wire can be seen running from the upper rear contact leaf to the left and up the wire sleeve.  The metal stop on the right side is also connected to ground, but folding it down, as I did above wasn’t necessary.

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Here’s the backside of the column housing with the old guide sleeve and J-connector installed over the new wires, and the hot pin for the washer pump installed in the slot on the bottom right.  Conveniently, the mate to that pin on the female side of the J-connector under the column houses an inactive wire that travels nearly perfectly to the washer reservoir in the front trunk. This was probably a provision for a washer pump option that wasn’t implemented in my 914 model.

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After installing the column switch assembly and mating the column connectors, the next task was mounting the electric windshield washer pump.  The Pelican Parts technical article recommends using the 12 volt VDO pump #191-955-681, which was easily found online listed as a Porsche 911 part.  Because the usual washer pump spot will be occupied by the new heater hose, I mounted it on the flat spot between the washer bottle and the trunk hinge, which misses the pump by about an inch.  I also included rubber insulators, so the pump won’t transmit vibrations into the car body.

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The original washer fluid bottle is airtight and designed to handle 45lbs of air pressure, but now must be vented to avoid a vacuum when the pump draws fluid from it.  The easiest solution is to remove the pressure hose from the cap, drill a small hole so air can enter, and continue using the standard feed hose connection on the bottle bottom.  One important addition is the one-way valve placed in the fluid line between the washer pump and the nozzles as seen above.  Without these valves, air will creep back into the system through the nozzle jets, causing an annoying delay in the washer fluid delivery.

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The next obvious step is to install the windshield, so I can wash it.