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JnC's Programmable Intermittent Wiper Relay Hack

36K views 54 replies 29 participants last post by  goRt 
#1 · (Edited)
Background
This is the story of a little black relay. It started life at the Doduco plant in Germany, then immigrated via a blister pack to Neuspeed in the USA. Around 1991, I purchased it and plugged it into a 1990 VW Corrado. When I sold the car, I pulled the relay. Then it found it's way into a 1999 Porsche Boxster. That is, until I drove a Lotus Elise at Deal's Gap (courtesy Mike Silberman of Lotus of Durham ;) ), and knew I had to sell the Boxster. But not that relay. It came out and went on a shelf pining for the Elise. I'm pleased to announce that this 15 year old relay has found a new home, in my 2006 Elise delivered earlier this week. :D

This relay is a marvel of Teutonic engineering. Simple, transparent, intuitive. Daily drivers will wonder what they ever did without it. Being smaller than the stock relay, it may actually improve your 0-60 times. Curmudgeons will rue the day, as this is too much luxury for them to handle. ;) Ok, so...

What does it do?
It does two desirable things for the Elise wiper system. The major one is the programmable intermittent time function. The minor one is it changes the number of wipes during a spritz to 3 instead of 5.

Instead of wiring up a potentiometer and repeatedly twiddling with a knob like you normally have to do with most cars, you can set a comfortable interval on the first try. No hacking up the interior, or splicing wires, or changing stalks. Just replace one relay.

Here's how it works... envision that it's misting on the windshield due to the weather in the canyons.
1. Flip the wiper stalk to the intermittent position to clear the windshield with one pass, then flip it back off.
2. While off the relay begins counting. In German...
3. When the mist on the windshield needs another wipe, flip the stalk back to the intermittent position.
4. The relay will now wipe the windshield based on the time interval that you set. The relay can "count" between 2-45 secs. The limits may vary by manufacturer.

In other words, push up on the wiper stalk to the intermittent detent to have it wipe once, push down to off and wait until you need to wipe again, then push back up to the intermittent detent and leave it there. Ta-da!

If you've not used the intermittent since starting the car, the intermittent default time is about 6 seconds, IIRC.

This hack may be familar to the VW owners out there or Europeans. It's very popular.
VW carries the relay: either 357 955 531 or 1HM 955 531B
Some VW aftermarket suppliers carry it as well. Cost ranges from $10-50 depending where you find it. Here's one for about $29 + S/H: World Impex Relay

Installation
Replacing the relay requires some dexterity. More so for the Elise.
First find the relay. It's mounted beside the hazard light relay. Turn on your hazard light and gently feel around for the relay block, located above and to the right of the OBDII connection port. There are two relays there, one above the other. You'll feel both of them pulsing due to their proximity. Turn off your hazard light. The lower relay is the wiper relay. To remove it, I found it was far easier if I opened the passenger door, and sat in the drivers seat with my feet out of the car's passenger side. Pull the relay towards the drivers door to free it. Pay some attention to how the relay was rotated when you pull it out. You can't insert the new one the wrong way, but it will save time if you have the correct orientation. Look at the pins, and replace with the new relay.

Disclaimer
And remember before attempting any project, be sure you possess the ability to perform the task correctly. I'm not responsible for running part changes, twisted backs, damage you may cause to your car, etc.

P.S. Thanks to Stan for putting up with my repeated PM's for electrical schematics. It wouldn't have happened without his info.
 

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#3 ·
Florida Chris said:
Thanks for the tip. Great mod. I'm off to the VW parts counter on Monday to pick one up.
+1! Great job!
 
#4 ·
Sounds great, but I'm confused about something.

What does: ":based on the time interval (between 2-45 secs depending upon manufacturer) that you set" mean? I expected you to say that the wiper interval would be programmed to be the same as was just done (i.e., "learn mode").

Thanks!

I hope it's loo late to benefit from this mod this year. I've had enough rain -- even light rain.
 
#6 · (Edited)
I think that's exactly what he meant - just that you can't get it to go less than 1 sec interval or more than 45 secs when you teach it. ie you move the stalk the first time to set the gizmo counting and the second time to stop it and set the interval which is variable anywhere between those time limits ...

Great idea - I am going to get one too! :clap:

Edit: ordered - I hate the 5 / 6 wipes after the cleaning fluid hits the windshield and everything gets smeared up and look forward to being able to adjust the intermittent cycle... I can see the real test is going to be getting it installed - I am about as flexible as a 2x4 :)

Thanks for the post.
 
#11 ·
GaryD said:
I think that's exactly what he meant - just that you can't get it to go less than 1 sec interval or more than 45 secs when you teach it.
Yes, that's correct. Sorry for the confusion. You can teach it to any range within about 2-45 secs. I think the upper limit may vary by manufacturer, but I don't see needing more than half a minute.
 
#12 ·
Congrats on your new Elise JnC. :)
I see it didn't take you long to start tinkering with it.
My recommended first two mods:
1) Left light pattern adjustment
2) Removal of shims including the ABS bracket.

Both are easy and can be done on a weekend morning.
Welcome to the Lotus experience, and sorry I stole the CO eBay Elise from you.. :D
 
#15 ·
Andrikos said:
Congrats on your new Elise JnC. :)
I see it didn't take you long to start tinkering with it.
Thanks Andrikos! Yes, I removed the shims this afternoon with the help of arandolph. Got my first beauty scrape on the clam too. No biggie, had to happen sooner or later. :tadts:

Andrikos said:
Sorry I stole the CO eBay Elise from you.
Yeah, you're so lucky my esnipe bid of $34100 didn't go thru. :D
 
#18 ·
JnC said:
Thanks Andrikos! Yes, I removed the shims this afternoon with the help of arandolph. Got my first beauty scrape on the clam too. No biggie, had to happen sooner or later. :tadts:



Yeah, you're so lucky my esnipe bid of $34100 didn't go thru. :D
Happy 1,000 posts!

Hey, all's well that ends well... :)
Enjoy your '06 and its probax seats, DBW and LED lights.
Sweet stuff.

Too bad I can't use your wiper mod as it NEVER rains around here... :D
 
#20 · (Edited)
Dave said:
Great write-up...nothing beats a good mod project :)
I thought this could be done from the get go. Had to buy an Elise just to find out. I feel whole now. :D

(Done so far... micromirror, trunk carpet removal for bootie, TrafficPro install w/ aux in, rocker stickers (cheapo, i think yours are better), shim removal, third brake light blinker, and the relay. On the todo list, showercap velcro, nautilus horn, v1 wiring, garage door opener wiring.)
 
#21 ·
JnC said:
This hack may be familar to the VW owners out there or Europeans. It's very popular.
VW carries the relay: either 357 955 531 or 1HM 955 531B
Some VW aftermarket suppliers carry it as well. Cost ranges from $10-50 depending where you find it. Here's one for about $29 + S/H: World Impex Relay
Thanks for the write-up on this mod, JnC. ET'ers who order the programable relay from World Impex (SKU 54591 - KAE p/n 3.200.110) may be interested know that the programming procedure for that device is a bit different from the Bosch relay described in your post. This link explains...

http://s-cars.org/postnuke/downloads/pdf/Pro-Wiper_Relay.pdf

When I first installed the KAE relay, I was sure the folks at World Impex sent me the wrong part. I couldn't program the thing to save my life. A little further research got me back on track.

As to which is better, I suspect, is a matter of taste. IMO, both are a big improvement over the fixed 4 sec. interval the stock relay provides. This mod, along with my new 24" Bosch Icon wiper, should leave me well prepared for the worst mother nature cares to throw at me this spring.

-Chuck
 
#22 ·
lucksta said:
ET'ers who order the programable relay from World Impex (SKU 54591 - KAE p/n 3.200.110) may be interested know that the programming procedure for that device is a bit different from the Bosch relay described in your post.
Thx Chuck for the feedback. There are so many manufacturers of these that each one is a little different. Folks may want to search for a different relay if the programming seems odd. Use the VW part number in the search field.
 
#26 · (Edited)
®ob said:
Germanautoparts.com has this 3B0 955 531 relay for 36$ It's not in stock. But they can easily get it.
They sell the KAE.

What's a good source for the Bosch part?

edit: I probably just get the KAE since it remembers it's state in the off position.
 
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