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Variable Intermittent Wiper Hack

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Variable Intermittent Wiper Hack

I installed this hack a few weeks ago and finally found some time to make some instructions for everyone. It is the same as the kit that shows up on eBay every few weeks , but will cost you about $40 less. The site with the original instructions disappeared, so I have figured out how to do this and made a PDF you can download. Basically, this hack enables the use of variable intermittent wipers in your 986 Boxster. It allows you to use a dash mounted dial to set your wipers to wipe at an interval between 4-30 seconds. This is a great addition to any Boxster especially if you drive in the rain. It is completely OEM and fully reversible (depending on a few choices). I have attached a PDF with the instructions, and there is higher quality PDF and set of instructions on my website which can be found here: http://www.bluboxster.com/Mods/The_Porsche_Way.html This hack works great, and I hope you enjoy it! :D


Edited by rick3000
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You can do that, and a lot of people like that way, but the relay costs closer to about $40. Plus, it isn't OEM, and you have to activate the windshield sprayers and spray your windshield to use it. So if you want to set a 30 second interval you have to spray your windshield with fluid for 30 seconds unless you can find the sweet spot to set the relay without activating the washers which is hard to do.

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  • 5 years later...

In installed the intermittent wiper control using these instructions:


Everything is working fine except the switch illumination. It stays lit all the time and the brightness adjusts in the reverse of the rest of the panel. When I dim the panel, the intermittent wiper control brightens and when I brighten the panel, the intermittent wiper dims.

For the illumination, I tapped into a circuit that runs to the back of the relay carrier at BS 5/2. I used this circuit to power the illumination on a targa switch that I installed to control a Homelink garage door opener. The illumination for the targa switch works fine, so I'm wondering why the illumination for the variable intermittent wiper is acting strangely. It shouldn't even have power unless the dashboard is on.

Any suggestions for fixing this are appreciated.

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It sounds like you may have tapped in to the always on 12V power instead of the variable 12V power (turns on with ignition). Did you splice into the existing wiring used by your garage door modification? I am not sure why it is is adjusting the brightness inversely, but I would double check all of you wiring first. You might also try temporary hooking the switch up to the cigarette lighter to see if that solves the issue, then you can start ruling things out. Best of luck!

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Thanks Rick

I thought I had spliced into the same circuit I created for the garage door opener illumination. I had a sketch of the circuits in my records. That said, I did the garage door opener work about 18 months ago and I may have missed something.

I used QShip986's instructions for the garage door opener: http://www.renntech.org/forums/tutorials/article/153-yet-another-way-to-add-a-homelink-device/

This required that I tap into the relay carrier to create two circuits. One (BS7) is for consumer-switched-off and BS5/2 is for the instrument panel LED lighting with dimming. This way, the switch is back lit and dimmed the same as the other console switches. The consumer-switched-off circuit goes into standby mode about two hours after the car is turned off, so if I had tapped into the wrong one by accident, it would have switched off by now.

I also used the same ground that I used for the garage door opener installation, but I did not ground that under the seat as QShip recommended. I'm beginning to think the power is coming from there in some way. I think that I will try a different ground and see how that works.

Thanks again.

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Thanks for helping me think this through. It turns out that the light needed to be on both the BS7and BS5/2 circuits. Attaching one pin directly to the ground caused in to be in the constant on state.

Everything is now working as expected.

Edited by KevinH90
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  • 1 year later...

Perhaps someone can provide some general information ...


Viewing the PET (parts system) it appears the potentiometer (the dashboard dial) for Boxsters is only standard equipment on S-models, i.e. option M008.  Or, it's included with option M265, Rain Sensor.  Incidentally, the potentiometer has a different part number with M265.


The thing is, however, PET only lists one interval relay, i.e. nothing different for models with the potentiometer factory installed.


That relay is 986 615 103 00


That's pretty similar to the 996 relay called for in the hack instructions, i.e. 996 615 103 00.


PET for 996 indicates this is standard equipment, although again there's a different part number if M265 is present.


My question then is why does the hack call for the 996 relay when PET fairly clearly indicates the 986 relay is used both with and without the variable intermittent potentiometer?  Is this something missing from PET?  Did Boxster S come with the 996 relay after all and it's just not shown in PET?  Inquiring minds ...


FWIW I can afford to buy the 996 relay but won't if I don't have to.


And, the links to the other instructions are obsolete so I tried to find answers elsewhere but didn't succeed.

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It has been a while since I did this modification, but if I recall correctly the 996 relay has more pins in it the than the 986 relay and one of those is the one that you are soldering a wire to. 


I cannot say for sure why the 986 relay is the only one shown in the PET.  It may be that the wiring harness in cars with the intermittent wipers is different than the ones without.  So, using the 986 relay works with the cars wired for intermittent wipers from the factory but you would need to come up with some kind of work around for the cars with the non-intermittent harness.


I've noticed that one difference between German and Japanese cars (if my experience with a 1996 Infiniti G20 and a Boxster can be used to draw a very general conclusion) is that the Japanese have one wiring harness for all cars of the same model while the Germans engineer a harness specifically for the options that will be put in the car.  For example, when I added fog lights to my G20, the harness and connectors were already behind the dash and front bumper.  All I had to do was add the hardware, a relay and a switch and I was in business.  On the other hand, when I added heated seats to my Boxster, I had to create and run a wiring harness for them.


The German approach saves material and is a more "green" process.  The Japanese method cuts down on mistakes.  Maybe that is one reason that Japanese cars are less trouble prone in general.

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Thanks for your response. If I learn anything earth-shattering, I'll post.

Have Mercedes parts ordered and noted they have a p/n for the pins to go with the connector block. The pins each cost more than the connector block.

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