R129 Impossible roof problem

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MVD

New Member
Joined
Feb 2, 2018
Messages
3
Location
Chichester, Sussex
Car
W220 S320cdi, W210 E240, W126 300se
Hi all, newbie here! First post… Hopefully in correct topic

Wondering if anyone could help at all? I've recently purchased a 1993 R129 SL300, it has a few problems, but the two I most want to sort out is the roof and roll bar. I've spent hours and hours on google surfing the forums, but no one seems to have had the same problem as me.

As far as I can see from videos, when lowering the soft top, the rear window needs the lift vertically.

This does not happen; it unlatches from the hatch (at the rear) but nothing else. If I hold the switch to lower the roof, while manually pulling up the rear of the roof vertically (rear window) the rear hatch then opens. But the front of the roof won't unlatch on its own, it just tries to pull down, I need to do this manually, once I do that, the roof will go down on its own and complete its full cycle with both the side windows going up when the roof is down. I can hear the bow extension limit switch click (I think that’s what it’s called?) this should be working because if I wiggle to roof while trying to open, the roof stops and starts with the switch being engaged/ disengaged.

When putting the roof back up, the rear hatch will open, the top will start to come out the hatch but then stops and it almost gets jammed. It will go forward about an inch, then backwards about an inch, all rather quickly as the roof tries. However, if I then pull the rear screen up at the same time, the roof will then close all as normal, front latching and rear latch closing. Long story short, the rear screen is dead. No resistance is felt when moving it, even when the roof is in operation.

After some googling, I thought I'd found the cause – ‘Bow extension cylinders’. I'm now having some doubts as I can't see any obvious leaks, everything looks dry, no puddles or drips of the floor.

I've driven the car to charge the battery - still doesn't work

Reset the windows multiple times - Still noting

Manually opened and closed the roof multiple times- Still nothing

Checked all fuses – All fine

I also think this has something to do with the roll bar, with the ignition on (position 2) both red lights show up then go out. When pressing the switch, I can hear the pump and a relay clicking but nothing happens at all. I've even tried to deploy it by taking a roundabout with some speed, was a little bit sideways, but it didn't deploy.

I was going to remove the bow extension cylinders tomorrow, but now unsure if that's the issue. Google and forums have been great up until now, now I just need an expert who knows everything there is to know about these roofs.

Hopefully someone can help, as I’m now sat scratching my head re-reading the same forums, going ever so slightly mad.

Thank you
 
Michael , first thing to do is read the fault codes from the ECU - this will tell you where the fault lies .

These cars are OBD1 , and have a 16 or 18 pin ( can't remember ) diagnostic socket just in front of the box which contains a few of the electronic modules . You can buy a blink code reader , or as I did , just use an analogue AVOmeter and count the kicks of the needle to read the codes . I'll add some links later tonight with further information how to do this , I'm at work just now and the info is on my computer at home .

I had a similar issue recently , after five years trouble free operation . It is likely just a limit switch somewhere not communicating . Since the rear bow unlatches , but then does not lift , I'd suspect one of the microswitches in the rear locks ( there are two switches in each ) since it is not communicating that this part of the sequence has been completed . I spent a fair bit of time greasing and cleaning the various locks , which had become dirty and stiff in operation , until they moved freely again , and I sprayed switch cleaner into the microswitches , then checked they were opening and closing correctly , using said AVOmeter , when they were actuated . The limit switches for both bow up and bow down are both adjustable , and need to be just right .

For your entertainment , here is the post I made on this subject a couple of weeks back .

R129 roof

Some information here , you test for roadster soft top faults on pin 10 of the 16 pin socket .

Mercedes 1988-1995 OBD1 code reader
 
Last edited:
PROBLEM SOLVED!!! (only 2 years have passed)

This is to help anyone in the future who was experiencing similar issues. I'm sure it's been covered enough, but here goes...

Turns out my roof control module was kaput, confirmed by my indie using a spare working module. I've tried to find the company I used, but no luck yet. I do remember it was around £350- £400. Usual thing, removed mine sent in the post & less than a week later it was fitted and hey presto the roof & roll bar was 100% functional again. Removal of the module is comprehensibly covered in many forums and from the links above, easy DIY job- Just do your homework :cool:

My biggest bit of advice to anyone looking to get their module refurbished, is to google the f**k out of the company you are thinking of using (common practice for anything these days). Loads of services available on eBay but dig a little, read the reviews etc (all the Benz forums were especially helpful with this ) and you should be good to go!

Thanks for the help from above members! I sold the car later the same year of my first post and haven't used my account till now as I totally forgot all about it! Better late then never eh. ;)

p.s. Will try find the guys I used as they were faultless.
 
Hi all, newbie here! First post… Hopefully in correct topic

Wondering if anyone could help at all? I've recently purchased a 1993 R129 SL300, it has a few problems, but the two I most want to sort out is the roof and roll bar. I've spent hours and hours on google surfing the forums, but no one seems to have had the same problem as me.

As far as I can see from videos, when lowering the soft top, the rear window needs the lift vertically.

This does not happen; it unlatches from the hatch (at the rear) but nothing else. If I hold the switch to lower the roof, while manually pulling up the rear of the roof vertically (rear window) the rear hatch then opens. But the front of the roof won't unlatch on its own, it just tries to pull down, I need to do this manually, once I do that, the roof will go down on its own and complete its full cycle with both the side windows going up when the roof is down. I can hear the bow extension limit switch click (I think that’s what it’s called?) this should be working because if I wiggle to roof while trying to open, the roof stops and starts with the switch being engaged/ disengaged.

When putting the roof back up, the rear hatch will open, the top will start to come out the hatch but then stops and it almost gets jammed. It will go forward about an inch, then backwards about an inch, all rather quickly as the roof tries. However, if I then pull the rear screen up at the same time, the roof will then close all as normal, front latching and rear latch closing. Long story short, the rear screen is dead. No resistance is felt when moving it, even when the roof is in operation.

After some googling, I thought I'd found the cause – ‘Bow extension cylinders’. I'm now having some doubts as I can't see any obvious leaks, everything looks dry, no puddles or drips of the floor.

I've driven the car to charge the battery - still doesn't work

Reset the windows multiple times - Still noting

Manually opened and closed the roof multiple times- Still nothing

Checked all fuses – All fine

I also think this has something to do with the roll bar, with the ignition on (position 2) both red lights show up then go out. When pressing the switch, I can hear the pump and a relay clicking but nothing happens at all. I've even tried to deploy it by taking a roundabout with some speed, was a little bit sideways, but it didn't deploy.

I was going to remove the bow extension cylinders tomorrow, but now unsure if that's the issue. Google and forums have been great up until now, now I just need an expert who knows everything there is to know about these roofs.

Hopefully someone can help, as I’m now sat scratching my head re-reading the same forums, going ever so slightly mad.

Thank you
my hood also not operating .1995 r129 sl280. at present operating it manually. merc supply a double ended tool in tool kit. To do so. instructions are in handbook also on line. It is a fairly quick 4 action 1 man job from the outside of the car. the hood on the r129 is a definate known weak area .lack of use in winter effects it ,some say the seals in hydraulic system dry up without regular contact with hydraulic oil .it is an incredibly complicated piece of design. u can spend afortune getting it fixed. parts are available but mechanics who understand the system less so. my car is 27 years old now so i cant complain to much about the hood.everything less still works which is the wonderfull thing about these old mercs if they are SERVICED of course. I seem to become less perfectionist with my old mercs as i get older and enjoy them more each to his own i guess' HAPPY CHRISTMAS and new year to all and stay healthy.
 

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