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Discussion Starter #1 (Edited)
Does anyone know if the CAN Bus-based rain sensors in the 4th gen CR-V (and later Hondas) can run the wipers in the 9th gen Civic? Has anyone ever tried installing one? (I believe the Australian 9th gen Civic was available with a rain sensor)
 

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Discussion Starter #2 (Edited)
Update: I was able to connect my CR-V sensor to my car, and the car seemed to recognize it. When I put the wiper stalk in the "intermittent" position, the wipers did not run intermittently, and moving the "delay wheel" caused them to wipe once and then rest (as they do on my dad's Accord, which has the rain sensor already). All good signs!

I unplugged my climate control unit (due to its easy access) and connected my sensor to the B-CAN lines on its connector. I grounded to my map lights and connected to 12V directly at the battery. In order for the sensor to connect, the car has to see it when it does its initial CAN check immediately after power is connected, so it needs a constant 12V source. I realize I could've grabbed that from the map lights as well, but I hadn't thought of that at the time.

I sprayed water on the windshield and unfortunately, the wipers did not respond. I have a few theories on that- I secured the sensor with painter's tape, so it didn't have the extra adhesive cushion it would normally have (it may not be capable of sensing that close). Additionally, the sensor connector has five pins, one of which I don't know the function of. It's possible that it's the IR LED driver, as I didn't see any IR coming from the sensor through my phone camera.

Another interesting mystery- turning the "delay wheel" to the second-lowest position doesn't cause the wipers to run and then rest like the rest of the positions do. I may need the stalk designed for rain sensing wipers.

I will keep this post updated and make a DIY once I have everything working.
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Discussion Starter #4
I learned a bit more- the unknown pin appears to be the sunlight sensor output. My vehicle already has a sunlight sensor so I won't be wiring that.
 

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Discussion Starter #5
Update: Today I tried attaching the sensor to the windshield via a piece of Gorilla tape (close enough to the required adhesive) and the sensor seemed to work as designed! Maybe not as well as it would with the correct adhesive, but it triggered the wipers appropriately! All right, this should just be plug and play from here on- expect a DIY soon!
 

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Discussion Starter #6
So I was able to get the sensor wired in and it works, but with a few bugs. First of all, because my Civic has automatic headlights already, I already have a light sensor message on my CAN bus, and that caused some flickering issues (because the car was interpreting messages from two different sensors, and they occasionally disagreed). I unplugged the light sensor and used some Arduino jumpers to keep it powered so it can still output an analog reading to the climate control system (in other words, only the CAN bus lines on the sensor are unplugged). This added two new issues- the "auto light sensitivity" option on the iMID menu is gone, and running the wipers no longer turns the headlights on. I tapped the CAN bus and saw that the message IDs coming from the new sensor are similar to the ones from my factory sensor, but not exact. They end in 4 instead of 2.

The sensor I bought came from Lithuania, I am in the US, it's possible that these are regional differences. I have no idea why the car would understand the foreign light and rain sensor outputs but not a foreign auto light sensitivity message. I used CANHacker to send the car the rain sensor message with a 2 at the end of its ID instead of a 4, and the car responded as if the sensor was connected. I'll do some more research and testing and keep you posted on what I find out.
 
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