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Intermittent Wiper Project

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I have a MY03 Boxster in which I'm installing the relay and rheostat for intermittent wiper operation. In all of the information I've seen concerning the installation of the rheostat, the left-side switch panel is "popped" off to gain access to facilitate the process. In my car, the left and right side switch panels are integrated with the trim surrounding the top of the central airconditioning outlet. Does this larger ptece, described in the parts manual as a "centre nozzle", P/N 996 552 263 01 01C, "pop" off too? Or are there some fasteners that need to be removed first?

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You pry off the single large trim piece. Pic is a 2003.

Thanks Tool Pants! A new topic for 9X6 Werks Volume 4?

Well, the relay and rheostat are installed. What's better is that the intermittent wiper interval is adjustable, as advertised.

But, now, I'm having a crisis of confidence in connecting the wiper rheostat internal lighting. (In things electrical, my wife refers to me as "Sparky" :eek: ) I would like to use the power source for the PSM tip switch internal lighting for the internal lighting power in the wiper rheostat. After looking at some of the online "hack" information, can I assume that lighting power goes to pin 3 on the back of the rheostat and pin 4 should go to ground? Now, looking at the wiring diagram for the PSM tip switch in my Bentley manual (Page EWD-104, Diagram 10A), can I assume that a source of dimmable power would come from pin A3 (Grey/Blue/Brown)? Of the remaining four wires on the PSM switch, is there a ground? There are no brown, "ground" wires in the area.

Thanks guys!

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Here are instructions for an older Boxster. http://www.johnfelker.com/pot/potinstnew.html

He says 3 and 4 are for illumination and 4 goes to any brown wire. Solid brown is usually ground.

For 3 I can't remember if the color coding changed in the newer cars.

Also, I see to remember that when you hook up 3 to a wire going to another switch that you should not use a switch that has an LED indicator, like the PSM switch. I think Sandy covered this subject in the 996 section when trying to illuminate a spoiler or some other switch.

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The wiper relay in my 1997 just gave up the ghost. Since I have to buy another relay I might as well get the one used on the 996/Boxster S and do Dr. Felker's hack. Plus my parts department has the potentiometer and 996 relay in stock.

The pot needs a 4 pin male connector. There are several pictures of this connector on Dr. Felker's site but no part number is listed. Also need the pins that fit this connector. Anyone with part numbers?

Loren has a 996 so he pulled the connector and sent me a picture. Looks like it is also used by Mercedes.

The second picture is from Dr. Felker's site and it shows a connector inserted in the back of the pot.



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The wiper relay in my 1997 just gave up the ghost. Since I have to buy another relay I might as well get the one used on the 996/Boxster S and do Dr. Felker's hack. Plus my parts department has the potentiometer and 996 relay in stock.


Just out of curiosity, why not just replace your dead wiper relay with the VW wiper relay that gives you the programmable feature, without having to add the potentiometer. It doesn't rain that much up by you, does it?

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Actually, once I determined the relay was the problem I called 2 local VW dealers to get prices on the VW programmable relay. $66 at one place and $53 at the other. 2-3 days to order. If VW had one in stock I would have picked it up that day, and the end of the story. Then I went on ebay and found this relay as a Bosch part, but both sellers were outside the US.

Then I called my local dealer to see if they had a 986 relay in stock. $19, but there are none in the US. But my dealer had the 996 relay in stock, and the wiper dial.

Then Peter told me the wipers would work (mine were not turning off) with the defective relay removed. I removed the relay and they worked, and I could turn them off. Peter was correct as usual. :rolleyes: The purpose of the relay is to park the wipers and for the intermittent delay feature.

So I was in no hurry. I took the above as a sign from the Porsche gods that I needed to do this "hack" and get rid of that round blank piece of plastic that I have been looking at for 7 years and put in the wiper dial. Plus I wanted to do this retrofit years ago but did not have a good excuse until now since I now have to buy a relay.

And if it ever does rain up here I'll be ready....


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This is from the 996 wiring diagram (connectors). It is the only 4-pin connector of this size that I can see. Might be worth a look?


Edit: I couldn't find anything on the AMP/Tyco web site, so maybe the best bet would be to go to a Mercedes dealer and see if they can recognise the numbers in Loren's photo.

Edited by Richard Hamilton
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Are those 1s or 4s in the part number and I will check out that connector with Porsche.

In the meantime, local Boxster owner Patrick who does work for Mercedes solved the mystery, together with Loren's picture of the Mercedes connector.

Felker used a cd-rom cable that already had connectors on each end, and one of those connectors fit the back of the dial. That is why a connector part number is not listed on his site, nor are pins.

I went to a Mercedes dealership by my house and ordered the connector used by Porsche based on Loren's picture. The Mercedes part number is A0285458428, called a pin bushing housing, with 4 slots. Used for a door switch thing on some Mercedes car. $1.70 and should be here in a few days.

I asked the Mercedes parts lady if she could show me the pins that go into the connector. She did not have just the pins, but had the pins already crimped on wires. The pins were the same pins that we use for the OBC retrofit, which go into the connector for the stalk. You can buy just the pins from Porsche, but I already have them. Or, I think you can use two 009 VW wires cut in half, and extend the resulting four wires - down to the relay (2 wires needed) and over to your illumination source (the other 2 wires) .

Nice lady, but she kept asking me what Mercedes model I had and what I was going to do with these parts....

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Just go down to your local Fry's or computer store. It's the same connector/pins that cdrom drives use. Even the locking clip type fit perfectly. I cut and extended the wires since they usually have a connector on each end of wire. It was free since I had one laying around.

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Here are the parts.

996 relay. Wiper dial/ potentiometer. Mercedes 4 pin connector.

The pins that go into the connector are the same as the OBC retrofit pins that go into the connector for the OBC stalk. You can see 5 of those pins I already had from another project, you only need 4 for the dial. For the picture I also stuck one of the yellow 009 VW wires into the connector.

And, I was wrong and Richard Hamilton was correct. When I said the cruise control connector would not fit the back of the dial I was thinking in my head of the 6 slot OBC connector when I responded, since I have never done a cruise control retrofit. Same style connector, but I was thinking of the 6 slot OBC connector I tried and not the 4 slot cruise control connector.

So there is a connector sold by Porsche after all for the dial. Use the cruise control connector, which also needs a cover for the connector. The Mercedes version has an intergrated cover, so the Mercedes connector/cover is sold as a single part.



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Whall bought that kit and I was thinking of buying it. You can buy the parts for about 1/2 of their price, for whatever that is worth. Frankly, the VW relay is probably the best way to go, but I have to get rid of that round plastic plug in the dash that has bothered me for 7 years.

You need to hook up 2 wires from the pot to the relay pins #1 and #6. Whall indicated that they drill a hole in the side of the cover for the relay so that the wires can be connected internally, via solder I believe. Nothing wrong with this method. In fact, to test the dial and relay I just shoved the 2 wires next to the pins as I seated the relay.

After trading messages with Whall, they do not use a factory type connector and use too large of a wire gauge. Again, this does not matter so long as it works.

But I want to see if I can do it like a factory install. I also do not want to use wire taps like they have in the kit, but there is nothing wrong with taps for this type of application.

Today I ordered what I hope are the female terminals for the relay pins. They only cost a few cents. If these are correct then I will be able to plug in the relay just like a factory relay. Also ordered terminals for the illumination, but I don't think I will need them.

Stay tuned for a factory like install or, if I give up, an updated "hack."

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I bought the intermittent wiper kit from the dealer on e-Bay. It offers a "clean", almost factory-like relay installation. I didn't want to have to be too creative doing wiring around the relay panel. The down side, to me, is that the wiring harness is too long -at least the way I have run it - and the wires (nos. 3 and 4) for the internal lighting for the rheostat are too heavy to be neatly tapped to an existing wire or piggy backed to an existing plug.

I bought a MB plug (see post #7) and a couple of -009 VW wires(see post #13). I am going to shorten the wiring harness and use the MB plug and VW wires to try to develop as neat a dashboard installation as the relay panel installation is. BTW, I think the 4 pin plug that comes with the e-Bay kit is a non-automotive generic plug (computer application?). It doesn't have the "ear" that snaps in and holds the plug in the back of the rheostat.

Still cogitating where to hook up the internal lighting. :huh: Maybe over to the cigarette lighter lighting.



Edited by whall
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I finally finished the installation of the intermittent wiper kit I bought on e-Bay. I modified the kit somewhat.

1. Shortened the wiring harness about 18-20 inches,

2. Removed a third wire from the wiring harness. The third wire was not connected to anything at either

end of the harness and because the wires are heavy and solid, removing the unused wire made the

harness more flexible,

3. Replaced the kit's rheostat plug with a MB 028-545-84-28 pin bushing and two VW 000-979-009 wire

sets cut in half,

4. The wires for pins 1 and 2 were soldered to the wires in the harness that connect to the relay,

5. The wires for pins 3 and 4 were routed to the PSM tip switch,

6. I removed the blue/red wire female connector from the PSM plug, soldered the wire from pin 3 to the

connector and replaced it in the PSM plug. I removed the blue/gray/brown wire female connector from

the PSM plug, soldered the wire from pin 4 to the connector and replaced it in the PSM plug. (I had

initially connected the wire from pin 4 directly to ground but found that the rheostat internal lighting

was on continuously.)

I found no problems connecting the rheostat illumination to the PSM tip switch. The PSM switch still functions as normal and there are no issues with the PSM switch LED. And - so far - no arcs, sparks or smoke. As a simulator instructor once told me, "you can't beat success". :P


Edited by whall
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Various terminals I ordered have showed up.

This one looks to be the female terminal needed for pin #1 on the 996 relay since it fits the smaller pin on the relay.

The only way for me to know for sure is to pull the relay tray out to see if I can plug the terminal into the back of the wiper relay plug.


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A question for Tool Pants.... Do you have a current part number for the programable VW relay. ??? I checked with a local dealer about a year ago with a part number provided from a previous forum post on the same topic .... the parts desk person said the item was unavailable.

thanks in advance

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The current VW part number is 3 B0 955 531 - VW use to have a different part number. On ebay there was a wrecking yard selling a bunch of used relays for $9 each. I asked the seller if he had this relay and he said he would look at a car, but he needed me to tell him what VW model and I was not positive which VW models came with this relay. I've heard Rabbit, Golf, and Jetta. One of the local VW places said 1984-1993 Rabbit when I asked what car used this relay.

According to the UK message boards Bosch also has a relay that does the same thing. For all I know Bosch makes the VW relay. Bosch is 0 986 335 058. Bosch calls their relay easytronic. I had no luck finding the Bosch version with a google search, but did find one on non USA ebay.



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  • 10 years later...

Fwiw, this connector is still being used in the 2017 958 for the LIN bus connector under the center console mode buttons (pas, diff, sport+, etc).  Albeit with just 3 pins actually in the connector instead of the four it can hold, one spot is empty.


TE makes it, but the -1 variant is restricted to automakers.  



Not sure but the -3 variant looks pretty much the same.




lin connectors.png


I generally try not to resurrect zombie posts from the dead, but search brought me here via the Mercedes number, and that gave me a jump on more search words.  Maybe the next guy will come along in another decade..

Edited by wkearney99
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