Early Bay Windshield Washer mod (part 3)

Continuing from the last 2 posts, this part of the washer modification focuses on the electrical. Sorry it took so long to get this out. I ran into challenges getting the switch installed, as you'll see. It does work, and I've already moved on to the next big thing... which I'll get to posting about soon, I hope :)

Pump Wiring
The pump has 2 pins. I can't speak for the vanagon pump, but the more modern pump I used doesn't appear to be polarity sensitive. Meaning, you can apply 12V to either pin, with the other to negative/ground, and the pump will run the same way. Neat. I wired the pin closer to the rounded end of the plug to ground. For a ground, I used the headlamp ground, and an insulated ring connector on the end of a brown wire (brown for standard ground color consistency).
The signal or 12V pin was wired to the wiper switch with a green wire. The other pin on the switch was red-wired to the number 30 terminal on the wiper switch. I mentally debated this point. I could have used another circuit in the fuse box, but finally concluded that having a single fuse/circuit dedicated to the wiper and washer should be fine load-wise and easier to diagnose later.
I tested every connection with a multi-meter, verifying that continuity existed before moving on to the next section. I also applied 12V at the terminal 30 and demonstrated that the pump would fire when the button was pushed before considering the electrical done. I still had the switch to install into the dash, but the system was otherwise complete... but, of course, getting the button into the dash is what started this multi-post topic.

Prepare the Switch

roughed-in mount
(pre-trimmed)

Arguably, this is getting into what you have most likely been waiting for. The old switch/valve needs to be taken apart. The valve is held on with 2 long brass rivets. Drill them out with a 9/64 drill bit. A slightly larger one might work too. Once the rivets are gone, the valve pops off. Grab the small rubber disk that sits between the button-rod and the valve; you'll need that disk later. In my case, when I separated the valve from the switch, the rubber disk didn't just sit there, it jumped and ran. Chase it, you'll need it. Push the long brass rivet remains out of the switch.

Fab a Mount
With a pair of tin snips, cut a 3/4" wide strip from some grade 24 ducting. Step-drill a 1/4" hole in the center. Bend the strip into the shape in the picture here, and then drill 7/64" holes center-aligned with the larger 1/4" hole. To prevent the strip from grounding against the tabs on the switch, it needs to be trimmed down with the tin snips. This takes a few rounds of test fit, trim, etc. File the sharp edges. Your fingers and wiring behind the dash will thank you. 

Put it Together

switch during testing

Once the mount is formed, slip the McMaster-Carr switch through the hole, include the washer and tighten the nut. With 2 #8 Phillips-head screws (not bolts) each at least a 1/2" long, mate the mount with the switch. Test the fit with the knob and button (with long pin) in place. I found that the button on the McMaster-Carr switch and the end of the long pin didn't exactly meet, so some fiddling with the mount was necessary before it could be fully torqued down. We now have a working switch. But when bench tested, the pin without the rubber disk doesn't hit the McMaster-Carr button cleanly 100% of the time. So, the rubber disk needs to be part of the final equation. You can see the disk in the "testing" picture. This is where it gets interesting.

Dash Install
The old wiper switch fits into the dash by being fed through from the front (front-is-front!). The new switch with the added washer activator does too, but there's a complication. In order to fit through, the knob and button with the long pin need to be removed from the switch. If the long pin needs to have the rubber disk set onto it to properly activate the McMaster-Carr button, then how do we assemble all the pieces? It's not easy. I tried spot-gluing the rubber disk to the end of the McMaster-Carr switch. No good. I tried removing the mount, installing the switch into the dash and then re-assembling in situ. Nope. I tried a few other permutations too. I was able to get the whole thing installed and functional by barely threading the McMaster-Carr switch into the mount, and installing the dash-switch into the dash hole like that.... with the dashpod removed so I could get my hands in there. Then, install the turny-knob (beware: technical wibble-ly wobble-ly terms ahead) onto the dash-switch. Next, hold the rubber disk against the dash-switch while feeding the button with the long pin through the turny-knob and press it into the tiny hole in the rubber disk. This is hard with thicker fingers. Now, tighten the nut around the McMaster-Carr switch to set it tight. Test the action with a multi-meter to make sure the switch activates properly. If necessary, the mount can be pressed tighter towards the dash for a reliable action. After all the fiddling, mine needs a slight adjustment.

Button It Up
Once in-place, test the washer system first without water. If the pump fires up when you push the button on the dash, you can then test with water in the bottle. It will take a little time for the pump to prime, and for the washer lines to fill. Once the water makes it to the nozzles, adjust them so the stream lands in the center of each wiper path. Once adjusted, verify the tightness of the various mechanical connections (pump to body, switch to dash, etc), put your kick panels back on, and you're done! Hazah!

That's it for today. Thanks, as always, for following along. I hope you found this useful. More next time...