Hi all,

A little history on my problem: I had problems with my driver side (Right) window jumping a tooth and a MB mechanic attempted to fix it. He was blaming the window switch at the end and as a temporary repair he piggy backed the the right side switch of the left side switch. Now the left switch operates both windows at the same time. I took it back to him for repair but now he can not remember where the wiring was changed excactly other than it was somewhere around the roof controller. I have included a pic of the connection where I think the changes was made. Can someone please advise or compare the photo to a original connection? I will appreciate your help.

 

I removed the insulation tape shown in the previous post and found this backyard connection (See attached photo). Can someone tell me what these two wires feed perhaps?
Green and white continues to the plug

and the green and blue wire is soldered to it. I assume the latter drives the right side window but can not find a wiring diagram anywhere.

 

Ahoy Razzmeister! I am with you on this problem. My controller has been diagnosed as BAD by Mercedes and they quoted me an ESTIMATE of $ 5,000.00 USD to replace and program the replacement top controller. Bad deal for MB. I now am not concerned about the top going up and down but, I would desperately desire for the windows to cycle when prompted! I have a hard top of which I can install however, I first need to be able to operate the windows which are controlled by the top control unit of which you speak. Now for "PLUTOE, you have came on too strong for this forum of GENTLEMEN MB owners. I too need wiring information related to the windows/top controller and appreciate Razzmeister's pics. If other do-it-yourselfers have similar info would you please share it on the forum. Thanks to all...... and do have a "jolly good ride!" Chetter sends

 

Razzmeister....... is the exposed electrical contact which is attached to the green/white wire, remaining in its present position or do you reinsert it into the conector?

 

Most of the "official" info I have seen from Mercedes treat this as you would a "board swap" in a computer so there are a few things they don't tell you. The biggest thing they don't tell you is that the cars tend to pre-date the era when manufacturers were making their own custom chips to control things so if you were to crack open the box the chips would all be found in the standard TTL books (transistor to transistor logic books that list standard IC chips) and you would be able to order replacement pieces from any electronics supplier. The problem you will run in to though, is figuring out which pieces are bad and that takes some electronics skill.

 

Wow! CWRobin........... now we are communicating..... Welcome aboard! Have you worked on the wires to the connector at the controller? Do you know of anyone that has done the chip trick successfully. My soft top/windows problem started when I replaced the battery in my 1995 SL 500. This happened in the fall of 2015 and I have struggled with it since. When I connected the new battery, positive (red) first and then the negative (black) next..... I drew a pretty healthy spark. Top, roll bar and windows haven't worked since that event. Can you steer me on? I have 26 years "aviation electrical" experience in the U S Navy......... long time past! I will celebrate my 80 th birthday on June 28 of 2016. Please help. You are a blessing for us. Chetter sends.

 

CWRobin would you have the Mercedes wiring color codes? such as brown-ground, etc

 

Most of the information I have been able to get has been derived from multiple sources. I have a copy of the original StarTec software (clunky, requires really old versions of Adobe and incredibly old versions of AutoDesk CAD software to use) and then there is http://alldatadiy.com/ which is around 20$ and has most, if not all, of the same information online but also includes a much better search engine and a bit more up to date information regarding how things are supposed to work.

Of course, with these cars there is a lot of "look for the black wire with the white stripe...now look for the white wire with the black stripe" kind of silliness that is part of MB wiring harnesses. This is where I end up having to derive answers from the workshop manuals...

Luckily, there tends to be, in both AllDataDiy and StarTec, information regarding what the voltages are supposed to be at the ports and electrical contact points during normal operation. This is where the electronics skill comes in. It is at this point where you end up going as far as you can in operation, checking what the values are at the various electrical points, and working it step by step.

I bought my 1991 500SL a couple of years ago (mid-life crisis present) and got it at a reasonable price (6,000) and my wife wanted me to have a hobby to work out frustrations and such. My wife has always joked it is better to have such a hobby "to keep me off the streets" but that joke is running rather true for my tastes. I spent the first year just completely re-building the convertible top system. I had gunk in the lines and some brittle wiring harnesses but the controllers were in pretty good shape. Still, I did have to investigate a couple of the systems for proper operation and to figure out exactly which micro-switch was not firing at the correct time and this involved popping the covers on the controllers.

I was surprised to find that each and every chip in the controllers was in my TTL book and were not that difficult to find online. So the chips are easy, as you can imagine, to replace since there is basically no surface mount stuff, it is all stuff that you would play with in a standard bread board back in the day. The hassle is in the wiring harness colors. Trying to find that information was just a bear and I actually found that depending on what time of year the car was built, or what work had been done on the car over the years, it was not really possible to rely on the colors of the wires. I have talked to 5 different people who own the same year of car as mine with similar problems and each one of us had a variation on the wiring harness color scheme. Don't know why, but that is what I have run in to so far.

The wiring insulation is horrible. It is a result of the EU "green" movements getting involved in manufacturing and the colors fade badly even when the insulation is not cracking apart and falling off the copper. Luckily, the troubleshooting guides, even from MB themselves, have you looking at specific connection points/connector numbers to use for testing.

The real reason there is not a good guide to the systems is that MB wanted dealers to use the completely proprietary testing boxes they had at the time. These things required a *specific* IBM laptop, with *specific* hardware configuration or the testing tools would not work at all. They believed in the "board swap" mentality back then (still do from what I hear) and the problems we all run in to now is that the testing units are either not available or are extremely expensive (last one I saw they wanted 25,000 for an old one reclaimed from a bankrupt dealership) or you can not find a laptop to use with the tools.

This is why I have retreated to the use of AllData and the original shop manual software to reverse engineer the systems. Luckily, I started life out as a "tech geek" and have continued on with that so I still have some of my old electronics debugging skills intact.

 

Now, with all that in the previous post, it *should* be possible to separate operation of the windows from everything else. The circuit is a largely analog circuit that uses 5 volt logic gates for operation of things so it is certainly possible to "fake the circuit" properly with the correct voltage levels. The only reason the operation is not separated is they did not want the windows to impede the top and vice versa.

The one piece I would fight to keep intact is the rollbar system. It is simply fantastic once you see what it does (there are videos out there showing crash tests of rolling R129's at high speed to show how the bar comes up to protect the passengers in that scenario) and it is something that *could* be split from the rest of they system. The problem is that it is something else that is designed to operate to avoid interfering with the soft top going up and down. However, this is something else that could be "faked" since it operates automatically at the beginning and end of the open/close cycle. The system, I feel, could be altered so that the top will not operate while the bar is up at all. Instead the system is designed to read what the current state of the bar is, then do the open/close, then restore the bar to where it was before. See what I mean about it being something that could be "faked" to work differently?

Haven't tried this myself since I have not had a reason to do so but I can picture in my head what needs to be done to make such a difference work.

 

Sorry I am not more specific help but I am currently spending my free time cutting the control arms out of mine since the retaining bolts have welded themselves to the inside of the bushing collars. Add on a full time, high pressure job and summer heat and I don't get to work on things as much as I would like.

My current project involves replacement of front lower control arms (bad ball joints and old bushings), replacement of all brake discs with slotted (to get rid of brake fade), replacement of rear shocks and replacement of rear bushings to get rid of some old rotten stuff there as well. After that I get back to work on interior items like replacing the old ratty automatic shift handle, re-wiring my newly re-built original spec radio since I have aux audio added on to it now (Becker autosound does really solid work on these old units) and finding a replacement for a broken piece of plastic here and there. All after I do a transmission fluid and filter change (thanks to a leaking pan gasket).

Then after this, I look at re-building the engine wiring harness from scratch since MB does not make them anymore and they seemingly yanked the rights to make new ones from Delphi here in the US. Not sure if I will re-build with new wiring entirely or simply re-insulate what is there currently but I sincerely question what the heck Euro folk are doing with the material choices in this stuff. I honestly think this is why *EVERY* euro car has electrical problems.

 

CWRobin...... Thanks you for this data, info, and tech dump. You are amazing. I have sent you a private message with info on my '95 SL 500 and a request that you call me at 601-520-0607. Hope to hear from you soon......... you won't regret the call. Chetter sends.

 

Very nice brief chat today CWRobin...... Good to know your location as that makes this simple. I will call you later this evening and I am aware that you are on EDT and I am on CDT. I sure was looking forward to seeing you drive away with my MB baby...... someone will. Later

 

All electrical schematics are available here. The top control is in group 77 of the main index; the windows are group 72. Internet Explorer is required as well as an older version of Windows and a plug-in by Autodesk called Whip4.