Adding variable delay wipers to a W123
 

The the stock delay wipers on the W123 have a single fixed interval. Often times I found myself wishing for a variable delay of the type found in many modern cars.

However, I didn't want to drill any holes for a delay control so I just lived with it. In an old thread about retrofitting "tap to pass" (Komfort Blinkers) several folks mentioned the lack of variable delay and proposed some custom solutions but the thread died. Fear not - there is a way!

Just like the Komfort Blinker mod VW provides the answer in the form of the 99 relay. This relay adds a variable delay to the factory stalk without any modifications.

With a 99 relay installed the delay position will work as before with a fixed interval similar in length to the Mercedes factory interval. However, the interval can also be user programmed! Simply turn the switch to delay and turn it off again before the wipe is completed. Once the desired time has passed just turn the switch back to delay and the new interval is set. A delay from a fraction of a second to about 30 seconds can be set.

Once the wipers are turned off (for longer than the programming interval) and on again the standard fixed interval resumes. So you can program it if you like or leave it alone. The great thing about this system is how intuitive is. Turn the wiper switch to delay, turn it off again, wait until you want it to wipe again then turn it back to delay. Most cars have an adjustment ring that takes several cycles to get just right. With this system the delay is determined by direct visual feedback. All other stalk functions remain the same. I've been using it happily on an 85 300D for several months.

The 99 relay is found in many late 90's Jettas. It can be found in other VW cars of that era too but the higher spec Jettas often have them. They are located on a relay panel under the steering column and are clearly marked "99" on top. I went to a local salvage yard and came home with 4 relays and sockets. Some cars have a socket block while others have removable single sockets. Sockets can be found in many VW/Audi cars even those without a 99 relay just take note of the pin configuration needed for the 99. VW uses many similar relays with subtle differences in pin orientation and size. Sockets can be re pinned provided they have the correct basic configuration.

The sockets are necessary because the 99 relay uses spade connector rather than pins. Aside from that it will directly replace the W123 delay relay (impulsgeber) without any mods to the basic wiring of the car. If you can solder, you can make an adapter using the 99 relay socket and pigtail with a salvaged Mercedes 6 pin connector. You don't have to hack the harness and you can always return to the stock configuration.

The delay relay on the W123 is located behind and to the left of the instrument cluster. It's possible to remove the relay and install the adapter by removing just the under dash panel but removing the instrument cluster will make the job easier.

The wiring for the adapter is as follows:

Mercedes Circuit # / VW circuit #

31 / 31
15 / 15
86 / T
J / I
31b / 53S
S / 53M

The circuit numbers are printed on the relays themselves.

This mod should work on several Mercedes models but as yet I've only tested the W123.

Thanks for the write-up.
I'll be adding 99 relays and sockets to next weeks trip to the bone yard.

I was also thinking of adding the afterwipe feature that Saab had to get that bit of WW fluid or water that runs down the window after you shut the wipers off.

There used to be a forum member who made an infinitely variable wiper relay. His name was techguy512, but I don't think he is around anymore. I bought one and love it. I should have bought two...


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Yes, he also developed and made available an enhanced function digital replacement for the tach amplifier used in later 123 and 126 diesels.

http://www.peachparts.com/shopforum/diesel-discussion/207837-designing-better-tach-amp.html

Nice, might have to do that. My first car, an '84 Mercury Marquis, had a very nice variable delay function and I've missed it on every other car I've owned.

Of course if I'd known at the time that it was basically a 4-door Mustang I probably would have kept it, but that's a whole other discussion.

-Rog

I just compared the 123 and 124 wiper circuits, they appear to be arranged the same. Unfortunately the interval wiper relay is rolled into a common package with the turn signal flasher and rear defrost timer relay (device N10). Next time I am at the JY I will grab an N10 and a VW relay and see if the guts will swap over inside the N10 package.

Unfortunately no such luck in the 210, the wiper is run from the front SAM and the wiper switch in the stalk just puts different resistances on a control line to the SAM depending on the switch position. Although I may try to retrofit an IR rain sensor if I happen to come across a JY car that has it. The ML has the rain sensor and it is amazing.

Someone PM me if you have a spare relay to sell. Thanks!

Sixto
83 300SD

Well I went to the JY a couple weekends ago and found two N10s from a Gen 2 126 and a 124. But no luck on the VW 99 relays, they were gone from the several VWs in the yard. Must be popular!

What year Jetta were you looking at?
I picked one out of a '94. A '97 didn't have one.

I'm in the process of adding the 99 relay to a W124. I've removed the relay in the N10 MB module and other components that go to the wiper related pins (few diodes and resistors). I could not find room to fit the VW relay in the W124 relay center so I'm going to mount it below connected with 2 sets of wires with inline 3 way connectors. 6 wires will come out of the N10 module. I'm doing it this way so I can easily switch back to the original MB module if need be.

I have a 92 VW idi Jetta and pretty certain there is a 99 relay but never knew this programmable feature. I'd have to try it out and see if it works. I also have one or more spare 99 relay in my stash.

Did some googling and found this on tdiclub forum 99 Relay mod (programmable wiper) - TDIClub Forums with a pic of said relay showing p/n. Searched for the p/n and found it can be had for as little as $7 https://www.*******.com/products?keywords=1HM955531

Not sure if that is the same relay but worth a try.

The programmable feature does not work in my 92 Jetta (it's fixed intermittent interval). It could be my relay is not fully functional or it does not have programmable delay. I missed the "A" suffice in the p/n in the pic of relay and there may be a difference. One has 5 pins and the other has 6. Not sure which is which and which is the programmable one. I have not pulled the relay in my Jetta to check p/n. Before buying the relay I linked to, I'd suggest verifying if it is programmable first.

My '92 Jetta does not have the programmable relay. It has a number 19 (fixed time interval) but I tried the 99 in it and it works great. I guess I'll be looking for more relays at the wrecker.

Good to know. Do you have a p/n of the 99 relay? Do you know if a new aftermarket programmable delay relay will be marked "99" or just the 9 digit p/n? I looked in my VW Bentley and could not find the designation "99" on the wiper relay anywhere in the manual
.
Is your 92 a diesel?

My relay 99 is part number is 357 955 531.
My '92 is gas.

The Seller had a web page for these. I think I visited it a year or two ago. Not sure if he is still selling them. Since the Seller already went through the hassle to make these commercially available, it might be a good idea to see whether or not they are still 'for sale' ... or at least determine if he stopped selling them altogether...

The 99 relay comes is several sizes with different part numbers. "99" is clearly marked on top so they are easy to identify. They all function the same. All versions I've found are based on the ST Microelectronics IC number DD920402.

They can be hard to find because they are plug and play in some Volvo and BMW cars.

If you solder it might be a good idea to replace the few electrolytics on the board.

Here is picture of the factory W123 wiper relay showing the pin out for making an adapter.

Found this listing on a VW Bus forum. Afew more models it was used in.



357 955 531 (original VW 99 relay)
or 1HM 955 531A or B.
The Bosch # is 0-986-335-058.
The number stamped onto the end is "99".

357 955 531A, 1HM 955531, and 1HM 955531C are the NON-programmable intermittent wiper relays.

Check Ebay should be $20-30 or find them in your friendly neighborhood boneyard.

1990 Volkswagen Corrado
1991 Volkswagen Corrado
1992 Volkswagen Corrado SLC V6
1993 Volkswagen Corrado SLC V6
1994 Volkswagen Corrado SLC V6
1995 Volkswagen Golf Cabrio III ABA
1996 Volkswagen Golf Cabrio III ABA
1997 Volkswagen Golf Cabrio III ABA
1993 Volkswagen Golf III GL 4 CYL
1994 Volkswagen Golf III GL 4 CYL
1995 Volkswagen Golf III GL 4 CYL
1996 Volkswagen Golf III GL 4 CYL
1993 Volkswagen Golf III GTI 4 CYL
1994 Volkswagen Golf III GTI 4 CYL
1995 Volkswagen Golf III GTI 4 CYL
1996 Volkswagen Golf III GTI 4 CYL
1993 Volkswagen Jetta III GL 4 CYL
1994 Volkswagen Jetta III GL 4 CYL
1995 Volkswagen Jetta III GL 4 CYL
1996 Volkswagen Jetta III GL 4 CYL
1993 Volkswagen Jetta III GLS 4 CYL
1994 Volkswagen Jetta III GLS 4 CYL
1995 Volkswagen Jetta III GLS 4 CYL
1996 Volkswagen Jetta III GLS 4 CYL
1990 Volkswagen Passat 16V
1991 Volkswagen Passat 16V
1992 Volkswagen Passat 16V
1993 Volkswagen Passat 16V
1995 Volkswagen Passat GL 4 CYL
1996 Volkswagen Passat GL 4 CYL
1997 Volkswagen Passat GL 4 CYL
1992 Volkswagen Passat V6 AAA
1993 Volkswagen Passat V6 AAA
1994 Volkswagen Passat V6 AAA
1995 Volkswagen Passat V6 AAA
1996 Volkswagen Passat V6 AAA
1997 Volkswagen Passat V6 AAA




I found this on another car site in the UK (Lotus)
vw relay part number 357 955 531 (This has now been superseded with 3BO 955 531


If this is a superseded number I don`t know for sure, could be a UK or lotus thing.

Any word on similar vintage Audis?

Sixto
83 300SD

Just noticed that the 99 relay that I picked up doesn't have the extra wipes when using the washer fluid spray. The original relay would keep the motor activated to give a few extra wipes after letting off of the WW fluid.
Not sure if all versions of the 99 are like this or I should be looking for another.

EDIT: I found that if I held the washer button a little longer than I normally do, then I got the extra wipes.

Yeah, I like the 3 wipes 'mist' feature in the '83 300SD. I mean when I bump the stalk too quickly to squirt washer fluid.

Sixto
83 300SD

All my 99 relays include the wipes after pushing the washer button - same as the originals. I'm not sure why yours doesn't. It may be defective as the cars equipped with these are 20 years old now. Capacitor / solder joint failure is possible.

I haven't found one in an Audi and I looked in 20+ cars.

FYI: I have read that the number 198 relay is the same as a 99 but I can't verify that. I can also tell you the number 197 relay is a standard delay wiper relay so if you look under the dash and see a 197 move along - the car won't have a 99 or a 198.

There may be other good numbers too. If in doubt open the cover and look for the IC number DD920402. The 197 board has a relay and some circuitry but doesn't have an IC.

Does anyone have a schematic of this relay in it's "native soil"? I'd like to understand how it can be wired for a non-Mercedes application.

Isn't that answered in the first post?

Sixto
83 300SD

No. Simply labeling the pinouts doesn't show me how this is wired into a circuit.

The circuit is the same sequence of operation for either the 123 or 124. I got this from the 124 ETM. I would imagine that the 1st gen 126 shares the 123 circuit with the independent relay, and the 2nd gen 126 the 124 circuit with the N10.

If you have a 123 or 124 ETM grab it and follow along it will be much easier to follow with a diagram in front of you.

15 is switched live, hot whenever the key is in position I or II.
31 is ground
86 is hot when the washer pump motor is triggered from the combination switch (triggers the wipe while washing feature)
J is hot when the combination switch is in the I position (intermittent position- enables the intermittent feature)
S loops back through the combination switch, when it is is in either I or 0, it provides a path to the low speed terminal of the motor, and connects to the common terminal of the internal SPDT relay. This provides a path for the internal relay to either connect the motor to the park/wipe switch within the wiper motor, or to constant hot, but only when the combination switch is either in I or 0.
31b is the motor output (internal relay connects between S and 31b when de-energized - allows the wiper to park between sweeps, and between 15 and 31b when energized - pulses the motor on intermittent time basis).

Here is the power path under normal operation (position II of the combination switch) this makes it easier to understand what happens normally.
Power goes from the constant hot through the combination switch to the "low" speed winding on the motor. If you were to put the switch in position III then the power would go to the "high" speed winding. These are connected inside the motor in a "V" configuration, the low at the top left of the V, the high at the top right of the V, and ground at the bottom of the V.
The wiper motor also has a park/run switch, which is SPDT. If the wipers are out of the parked position, the common terminal has switched 12 Vdc, and in the parked position, the common terminal is grounded. The common terminal of the park/run switch is brought to the 31b terminal on the relay.

So when you turn the combination switch to 0, and the wipers are not in parked position, the power flow is interrupted from the normal path (through the contact that closes power directly to the motor from the combination switch contact) to the alternate parking path.
This path is:
Switched hot to the "not parked" position of the park contact. The motor is not in the "parked" position, so power flows out the common terminal of the park switch to 31b of the wiper relay. This is the normally closed contact of the internal relay in the intermittent controller. The voltage goes out the common contact of the intermittent controller to the combination switch. Then it passes through the second contact in the combination switch that is closed either in I or 0 position. From this switch it is internally jumpered to the hot side of the low speed winding.
This provides voltage to the low speed winding until the wipers move into the parked position. Once the wipers reach the parked position, the park contact moves to the "parked" position, which applies ground to this circuit. This not only removes the voltage to the motor to make it stop moving, but it also grounds both ends of the motor windings, which acts as a dynamic brake to make the motor freeze at that position, instead of drifting on. If it did not do this the wipers may float back up due to inertia, to the point where the park/run switch flips back to the hot side, and the wipers would run again.
Ok so that is the normal operation. The intermittent operation is just like "parking" except it does it over and over again on a timed basis.

When you go to position I, this energizes terminal J, which energizes the relay momentarily (for about 2 seconds), the relay de-energizes, the timer runs the time delay, and then the relay is energized for 2 seconds and the cycle repeats as long as you are in I on the combination switch.
While the relay is energized, it applies voltage to the line coming from the park/run contact back through the combination switch second contact to the low speed winding. In effect what happens is the motor runs, parks, runs, parks repeatedly every time the relay pulses.

When you wash in the 0 or I position, terminal 86 goes live, which energizes the relay long enough to get 3 wipes then it either shuts off automatically (0 positon) or goes back to intermittent operation (I position). If you wash in II or III it just pumps while constantly wiping since J is not energized.

What VW did to their relay is add internal logic that detected how long J was energized to develop the time basis between wipes, instead of just having a fixed delay like MB did.

Thanks. That should do it.

Yep, my 92 has the 19 relay. No Pick-n-pull yards around here so had to resort to Ebay. Got a 99 relay $11 shipped local US. Plugged it in my Jetta and it works as advertised. Not sure if I will get a 99 for my W123.

Most sources of 99 relays seems to come from Europe
357955531 | eBay

FYI, if you ever find one of the KAE 99 relays they are "programmed" in a different way: instead of turning the delay on and off, you tap the windshield washer.

My Mk2 Jettas (85, 91, 92) and C3 Audi 5000 had fixed interval 19 relays. I upgraded all of them to the 99 relay. Oddly, by 98 / 99 the Mk3 Jettas had gone back to the 19 fixed delay relay. B3 Passats always had them, however those cars are just about all gone now :(

Eventually I want to put one of the 99 relays into my SDL. My plan was to simply disconnect the wiper motor wires from the multifunction relay and stick the VW relay in the bottom of the fuse box.

Here's the VW owner's manual supliment from 1994 showing how the system operates: https://youtu.be/zCHp2Qg_ngI?t=6m46s

PS: If you want another VW relay upgrade for your MB, why not add tap to pass turn signals? http://www.peachparts.com/shopforum/tech-help/275418-how-retrofitting-tap-pass-turn-signals-your-w123-w124-w126.html

-J

Any update getting this to work on a W124?

I installed it in one of my W124's. Instead of messing with the wiring in the base of the multifunction relay, I modified a couple of spare N10's to have pigtails coming out of the module going to the 99 relay. This allows me to switch back to the original N10 without much work if needed. The first N10 got in-line connectors to relay 99 but the second went directly to the VW socket. I figured if I wanted to remove it I could just remove the terminals from the VW socket (the VW socket was too large to go through any of the open holes in the relay center). There was no room in the top portion of the relay center so I mounted 99 below fastened with a nylon tie.

Relay 99 has been working great. The other car will have to wait until I pick up another VW relay.

Photos show 2 different versions of the 201 821 00 47 made by different manufacturers. Components connected to the wiper related pins have been removed.

Edit: I need to update the second photo. There is one diode that is removed that needs to stay installed (from terminal 15R)

Nice mod! I had thought about trying that too.

Hmm, one of the relays in there must be for the wiper motor. I wonder if it could be removed, and the guts of the VW relay put inside the MB relay case....

-J

The wiper relay has been removed already. The remaining 2 are for signal flasher and rear window defogger. I would have liked to put the VW guts inside but I can't see there being enough room.

Edit: I opened up the VW relay again and it might just fit in N10, especially the first one pictured that is mostly surface mount circuitry on the bottom side of the board. A project for a cold winter day.

VW relay 99 circuit board added inside N10 multifunction relay.

This is in a relay manufactured by a company with a symbol that looks like JWT that is almost all surface mount. A few components had to be removed, a trace cut and a couple of components relocated to get the 99 inards to fit. The board gets held in place by non-corrosive RTV.

The other common manufacturer which has the symbol LK in a circle would be much more of a challenge as the ones that I've seen are through hole technology with little room.

Nice work! Your W124 solution gives a completely factory appearance.

I'm glad you mentioned non corrosive RTV because it's critical for electronics. Acetic acid from conventional RTV will eventually destroy the board.

When servicing boards many times you'll find a large cap will be glued to another component using glue or RTV. When replacing these parts the adhesive used must be safe for electronics.

Oftentimes the replacement capacitor will be much smaller than the original negating the need for adhesive support. However, large parts will need the support to avoid cracking the solder joints on the board.

Has someone gotten this mod to work on an '83 SD? I tried with two separate 99 relays. Both have no interval function and no return to park function. AFAIK the wiper relay wiring is identical between the 83-85 SD and 123 down to wire colors. On the plus side futzing with the relay socket got my washer pump working again.

I'm quite sure it's a poor connection somewhere :/

Sixto
83 300SD
98 E320 wagon

Very, very cool! Thanks for posting.

Unfortunately none of the N10s or 99s that I have are the versions required to make this work as you have. I will probably solder the wires on the yellow board N10 as you did in the previous post directly to the blades on the 99. If I affix the 99 to the right side of the N10 there's looks enough room in the W201 fusebox area for it to fit by the two aluminum-housed ice cubes, but definitely not both the relay and socket.

I'll keep on the hunt for the N10 and 99 that you're using. The correct 99 may take a while to find, but I should at least have the variable int wipers running soon.

There used to be a forum member who made an infinitely variable wiper relay. His name was techguy512, but I don't think he is around anymore. I bought one and love it. I should have bought two...

The 99 relay that I used had only 2 components on the top side of the board, a relay and a 1uF 50 volt electroytic capacitor. The relay gets removed and I added a surface mount capacitor on the copper side to replace the 1uF. I used the SM cap only because I had a bunch that I'll never use up. A conventional cap could be mounted horizontally. I ground the circuit board down on the connector end to make it as small as possible. Looking at the photos on page 2, I would imagine other versions of the 99 could be made to fit.

When I get another 99 relay I'm going to mount one in the LF N10 module.
There are a few capacitors that I'll replace with stubby ones to get enough room. I just don't like gluing the 99 circuit board to the component side of the board but it has to be securely mounted.

A long time ago, I made a circuit for my first car, a 69 Sunbeam Alpine.
It had 2 adjustments. An interval setting and another for the number of wipes per interval. It wasn't my design but one I found in an electronics circuit book.
It was luxury to have that feature back then.

Were the SD and the 99 relay fully functional before you did the mod?
I have installed a 99 relay in my 92 VW and used it a few times in the rain and love it so much that I'll be converting my 85 300D to a 99.

I have 3 more 99's coming from Europe. They will be tested in my VW before the conversion of my W123. I'll have one extra (or two, depending if my 81 VW Caddy will accept a 99) tested 99 relays available. pm me if interested.

The original relay was working except for the washer feature which came back to life after refitting the relay. I have two 99 relays from the scrap yard but no way to test them. At this point I don't even know that the relay wires I added from a tail light harness are making contact with the fuse box socket. I'll obtain another MB relay so I can be sure the wires are making contact.

Sixto
83 300SD
98 E320 wagon

The movie about the invention and lawsuit of ford over the "blinking wiper motor" is on Netflix... cool movie.

Flash of genius

Ford crushed the poor guy, didn't he?

I'm able to hear the intermittent motor and relay going if I listen for it in my 123.

The Germans beat me to it!

W123-Database - Programmierbarer Intervallschalter für den Scheibenwischer

This tutorial has some great pictures of an alternate approach for getting the 99 in a W123. Unlike my mod no adapter harness is required. This is the W123 equivalent of Rick76's mod for the W124.

Google translate will give readable text but even without translation the pictures make the procedure very clear.

I opened some W123 relays and some 99's and found enough unit to unit construction differences to make this approach more of a general guide than a step by step. Even so the end result is plug and play.

I wonder if these could be made to work for a w123?

Programmable Intermittent Wiper Relay | GoWesty

That looks like a 99 relay for a bit more than I paid for 3 on *bay.

x2. Walks and quacks like a 99 relay.

Sixto
83 300SD
98 E320 wagon

I picked up another 99 yesterday at the wrecker. $5.

Beware of eBay sellers with multiple relays for sale at low prices, sellers that have a low of number ratings. I did a BIN of 4 relays from a seller that had 7 for sale. Listing said located in Spain but shipping showed from China. The seller modified the ad to double the price after I bought mine so I figure they discovered that they sold them too cheaply. Three weeks later and they haven't been shipped and the PayPal payment has yet to be accepted. No response to emails so I figure they are trying to avoid honouring the sale.

Edit: Beware of eBay seller pavlblokhi_0 and simkhachatrya_0 (same person) if they relist these relays.