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Discussion Starter #1
After going round and round with the wiper functions on my '02 Aero "Problem Child" I've moved on to some engineering. As it turns out, my Aero had the rain sensor from the factory but at some point in its history had the windshield replaced with a non-rain sensor part and the sensor was junked. It threw me off because the DICE was re-programmed as "no rain sensor", which does no good since the wiring harness is different between the two. There was also some hair-brained hack-job in the wiring harness that tried to get the intermittent wiper position to trigger the wiper motor (didn't work).

The key to determining if you have the sensor option is to look in the engine bay relay box. The regular DICE-controlled wipers only have one relay...the rain sensor option adds a second relay (helpfully labeled "rain sensor"). The first relay triggers the wiper motor, either by the DICE or by the sensor module. The second relay selects hi or low speed wiper mode, commanded by the sensor module.

I admit to a bit of simple-minded module swapping before I hit the WIS schematics. I replaced the DICE with the same P/N, thinking that I had a faulty one. No dice, as it were :)

So now that I've found the disconnected 9-pin connector (looks like .1" centers...easy) and groked the schematics I'm going to whip up a simple Arduino controller that mimics your basic timed-wipe function that you get from the DICE-based system. I don't think you can hack the wiring to make a rain sensor optioned 9-5 work off the DICE like a non-sensor 9-5 does so a simple uC-powered solution seems to be the best bet. It needs to handle the hi-low speed wiper selection, timing in intermittent mode and wipes during and after washing. Should take a few weeks since I'll gin up a PCB for it via a board service. The tough part will be trying to fit it into the headliner...
 

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A little off your topic but... one of the reasons rain sensing wipers are problematic is that the unit's sensing "membrane" (the clear rubber-like overlay that is part of the sensor and presses against the windshield) must be held tight against the glass. On my '08 the windshield must have been replaced at some point and the glass installer reused the mounting bracket that is adhered to the windshield; the sensor mounts to this bracket with two metal clips. The sensor's fit in the bracket was tight but the bracket itself wasn't adhered well along one side so the membrane had a slight air gap. As a result, the sensor didn't always work or work consistently.

I fixed it by carefully putting a few drops of super glue in the gap (between the mounting bracket adhesive and glass) and pressing the frame against the windshield until the glue cured - about 15 seconds. The frame and membrane are now tight against the glass and the sensor works as it should.

If yours doesn't work correctly, with the ignition on and Auto wiper setting on, try pressing the unit against the windshield while an assistant sprays water near the sensor eye: if the wipers work then the sensor may not be tight enough. Others have removed the bracket, scraped off the old adhesive and reapplied with double-sided tape. But, the tape must be very thin - if too thick there will be a gap between the membrane and glass and it may not work.
 

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Unfortunately the OP no longer has the sensor available to press against the glass and is just trying to reconfigure the arm switch to use it for the intermittent function.

I myself would love to get rid of the (pretty useless)sensing option and reconfigure it myself to intermittent mode and had hoped it would be a Tech2 change.

Looks like its more involved but I do hope someone finds a solution!
 

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Understand what he's trying to do and hope he's successful with his work-around. I agree that this is a feature I could do without; I'd much rather manually control intermittent wipers.

I chimed in because I don't like when something doesn't work as designed. I found that the sensor is way too sensitive and wanted to find out why. Thought others would see the title and be interested as well.

Merely lightly touching the sensor caused it to work and closer examination showed that by moving it closer and farther - like a 64th of an inch - to and from the windshield could be the problem. Vibration and bumps caused it to work/not work.

Gluing it so it's steady and using the adjustment lever on the stalk to fine-tune it and it's working again, for now.
 

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the windshield in my son's '99 sedan that we're tearing apart is already broken. A sawsall and a few minutes we could cut out the section of the windshield with the sensor in it

That's after we get the engine out of the sedan and into the wagon. Highest priority is to get the wagon running. After that the sedan gets torn apart, at least a good bit of it. (I'm trying to keep it "rolling" so it can be towed away at some point)
 

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Discussion Starter #6
Thanks for the offer Unclemiltie but I'm not looking for a sensor since my windscreen doesn't have the opening in the center silkscreen area that's needed. Thus my self-appointed quest to build a better mousetrap.

I got the basic design concept down and checked the signals at the connector to see if they jibe with the WIS schematics (they do) so now I just have to design the PCB and write a bit of code. I've found that most of my time in design is researching parts. For example, I have to drive two 12V relays from a 5V Pro Micro board so there's some glue electronics that need to be laid out. I started with the basic N-channel logic-level MOSFET setup (3 parts per relay drive) and after some hours of cruising the on-line catalogs found a single IC (the On Micro NUD3112) that would do everything for both relays. And it's $0.80 in single-lot quantities!

Everything else is voltage dividers and power regulation. All the signal conditioning (debouncing, etc.) is done in code, where it's cheaper and takes no board space.
 

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You can modify wiring to basic version.
I have done this modification to one 9-5, but installed rain sensor to basic versions in five 9-5s.
WIS shows both wiring schematics, you just re-route wires.
After this you might have TECH2 to reprogram DICE to basic version. No hardware needed.
 

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Discussion Starter #8
From all my poking around, it seems to be a large, untidy job to hack the wiring harness to go to the DICE-controlled wipers. For example, there's no existing splice-point to swing the variable resistor on the stalk over from the rain sensor connector to the DICE connector. You have to dig into the DICE connector loom. Also, you have to hack around the low-speed/high-speed differences, controlling that relay via the stalk switch. I keep on thinking that SAAB wouldn't have had different wiring harnesses for these kind of options but that seems to be the case.

Meanwhile, I spun a board for my project and should have it in a week or two:
 

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Mod sounds much harder than actually is.
When I installed rain sensor, modifications took about 30 min.

In my sight your PCB layout took 2 hours and total about 5 hours to have working wipers.
 

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Discussion Starter #10
I got boards and parts this past week and put one together just in time for the big rain today. Got to chase some logic bugs in the code (post-wash wiping issues and some funny timing issues with intermittent wipers) but it's working.

The photo is the test-bed version, with a Pro Micro on a DIP carrier. The final version will be slimmer and I'm working on a printed case now. I'll post everything on CircuitMaker when it's solid. About 15 hours of labor and $40 in parts (for 3 units). I got to learn Altium's free design suite in the process; it's a decent alternative to Eagle CAD but can be a little pokey in performance.
 

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