Independent washer/wiper control

[Luns]

The wiper/washer controls of cars I've owned seem to have made progressively less sense over the years.

With my '94 Corolla, pulling the stalk will run the washer (just the washer, only the washer, nothing but the washer). I would do this for a second or two to load up the windshield with fluid and let it soak whatever I want to clean off, and then I push the stalk upwards to make it swipe. The washer was fully independent of the wiper, and I was happy. Things had worked exactly this way for decades before, with the controls I had for a '72 Beetle functioning the same way (albeit with pneumatic washer rather than electric!)

Forwards a few years to my '06 Civic. Now I can pull on the stalk for a half second or so to wet the windshield, but any longer than that and the wipers would start to wipe the (not quite wet enough) windshield. Sometimes I can pull for just a short enough time to not start the wipers, wait a bit, and then repeat to get more fluid on the windshield before wiping. This had been tolerable, but I would still prefer the wiper to not kick in quite so fast.

Now with my '17 86, things have gone too far. Pulling the stalk to run the washers, the wipers start wiping immediately, totally dry across the windshield, before the washers even get to pushing out any fluid. I remember owners' manuals in the past warning specifically against running the wipers dry, but the controls now make it impossible to not do so! The wipers make at least two swipes, dry, before any significant fluid gets delivered to lubricate things.

The solution turns out easier than I'd feared. With my Honda, this interaction is handled within the gauge cluster, and was too difficult to separate cleanly. With the Toyota wiper controls, everything is handled in the wiper switch unit.

I won't walk through removing/reinstalling the wiper stalk from the car right now - there are youtube videos out there showing switch replacement on Corollas and Camrys, and it's not significantly different for us. I'm not sure what's left is enough to constitute a DIY, but I may come back to flesh out those details later.

With the stalk out, there's one screw to remove, and three plastic snaps to get the back off the switch assembly. Once in there, you'll face the circuit board shown below.

The resistor I've circled is what feeds the washer control into the switching transistor that trips the intermittent wipe relay to start the wiping. Removing this resistor separates wiping from washing, making things work like they did on my '94 Corolla.

There is a capacitor after this resistor, and it may be possible to replace this resistor with a larger one that charges the capacitor slowly enough to put out a reasonable amount of fluid, but still swipes before needing to deliberately do so. The existing resistor is 18k, and from the other values present, I estimate we could use something up as large as 1M without being too weak to trip the wiper at all, the same as not having the resistor at all.

I'll update this thread if I get around to experimenting with other resistor values, but in the meanwhile, I'm happy without the resistor there at all.

[RACECAR go brrr!]

Neat mod, and good writeup... but it sounds like something is wrong with your washer motor, lol. When I pull the stalk, I get washer fluid instantly, so the wipers starting at the same time isn't really an issue.

[Luns]

Originally Posted by RACECAR go brrr!

Neat mod, and good writeup... but it sounds like something is wrong with your washer motor, lol. When I pull the stalk, I get washer fluid instantly, so the wipers starting at the same time isn't really an issue.

Actually, I don’t think it’s the motor but the hoses.

Eveything is supposed to stay full of fluid so that when the motor runs, it doesn’t have to first fill everything before fluid comes out. However, if there’s a leak in the hoses, it’ll let air in, and all the fluid in the system can run back to the reservoir after the motor stops. Of course it’ll also leak fluid out when the pump is running, but as long as it’s a minor leak, you’d likely never notice it.

My windshield had been replaced by a prior owner. Hoses were certainly disconnected somewhere when removing the cowling, and probably weren't reconnected as watertight as they should be.

Still, even with instant fluid, I wouldn’t be happy. I came back to a massive bird dropping on my windshield the other day. When it’s the bad, I like to soak with a lot of fluid and wipe off with a paper towel rather than chew up my wiper blades smearing it all over the place. I could do that with my previous cars but not with the 86 before the mod.