R129 Roof switch & Roll bar switch glowing - Roof not working
 

I'm hoping someone can help and I apologise in advance for the long story...

Roof switch & Roll bar switch glows and the roof dosen't work. The roof did work when i viewed it, but it did need a hand on a couple of ups and downs (because i was told it had not been used for a while), plus the passenger window didn't go all the way up. So i offered him £250 less so I could get it fixed - as he didn't mention any of this before i drove 2 hrs to Birmingham, UK to view it. He said he would rather put a roof ecu which didn't work from another low mileage SL into it, than sell it for £250 less. So i walked away..


On the way home he rang me to accept my offer. I came back 3 days later to collect and on the way home i noticed the roof switch & roll bar light on - i wasn't aware what this meant at the time. Now it doesn't do anything, so I'm pretty certain he's swapped the ecu's over.

The passenger window now works after a Merc specialist greased it up (although it's a little slow), but now the drivers window does nothing (stays closed) - it was working perfectly fine before. Quite frustrating, but i guess this could be linked to the roof ECU?

Using a wire with an LED I connected pin 1 & 10…. looking at the roof switch it continued to glow red with no flashes. I repeated this action several times and the roof switch & roll bar light continuously glow red. The LED on the wire did not even light up.

When I connected pin 1 & 7, the LED flashed twice (I’m 99% sure it was 2 flashes. I repeated and it did not flash again. From the list of codes – 2 flashes = Roll bar control unit
Pin 1 & 16 just glows red.

Do you think I should send the roof ECU to get refurbished? I’m being quoted £300.
If i can locate the tool, shall i manually remove the hard top and try reading the codes again?

I hope someone can make sense of my problem??
Alex

I replaced all the fuses in the rear and now the driver window is working! Yes!!
The fuse box cover is missing, so moisture got to it and corroded them. Although i noticed fuse no. 4 (which is shorter than the others) is missing - does anyone know what this is for?

Top Hydraulics is an excellent source for diagnosis. Klaus can help you ferret out many issues. Does the top system have fluid? ( under the spare tire ) When you move the "top" switch, what sounds are made? ( chime, gurgle, fluid gushing etc. ) Does the roll bar move from dash switch activation ?

I've checked the fluid and it's at max. The top does nothing when I move illuminated roof switch - nor does the roll bar switch. I have found that I don't have the tool to manually remove the hood.
When I turn on the ignition there is a wurring noise, sounds like a motor is trying to do something... this noise comes from where the petrol cap is. The noise lasts around 30-40 seconds.
The roll bar light on the dash stays on the whole time, as does the roll bar switch light & roof switch.

Update:
Car is in the hands of an indie and they've confirmed the roof ECU needs refurbishing for starters...
Won't see the car until after xmas/new year. Will keep you posted..
So for the time being... have a merry Christmas all !!

Update:

My indie sent the roof ECU to BAA for testing. The result is that unfortunately it is not repairable, as the electric board is badly burnt!

The broken ECU will go back into the car, so at least i can have the car back. On the bright side at least the windows work (as without the ecu in place the windows will not opperate)! Or they did work....

So i'm on the hunt for a refurbished ecu, not wanting to get ripped off buying a new one! With the technology these days £1000 + tax is crazy!!

'90-'94 RST controllers are interchangeable, as are '95-'02
 

AGod,

you did the right thing on the technical side. First reading the codes yourself, determining that the code read implied a bad RST controller, and then having it sent in to be checked out. Chances are that the damage will not spread any further, meaning you will be able to move the windows until you come across a working replacement controller.

Most RST controllers/ECUs can be rebuilt, but you need to replace yours. Hope you'll get lucky on eBay or on some junkyard.

It is easy to swap controllers yourself. They are located under the right rear storage compartment. All you need is a 10-mm wrench:

- First disconnect the negative pole (only) on your battery
- remove the black cover in the right rear compartment (one 10-mm nut)
- remove 10-mm screw that ties the controller to the chassis
- disconnect the electrical connectors
- swap controllers
- reconnect electrical connectors
- make sure to bolt down the controller again; ground connection is important
- replace cover
- last, reconnect negative pole on the battery
(- on model years '95 and up, synchronize the windows as described in the owner's manual)

The following p/n controllers are interchangeable on model years '90-'94:
1298200097
1298202426
1298202526
All of the above controllers have three connectors, and the roll bar is governed by a separate controller.

The following p/n controllers are interchangeable on MY '95-'02:
1298203226
1298203126
1298203926
The three controllers above have two connectors, and the roll bar function is integrated.

Hope this helps, and good luck hunting,

-Klaus

klaus@tophydraulicsinc.com

Many thanks for your detailed info!

I've managed to find a roof ecu from a breaking SL where the roof was functioning ok. I disconnected the -ve battery and swapped them over... The roof switch light has gone out http://www.mbclub.co.uk/forums/images/smilies/smile.gif however the roll bar light flashes and the roll bar light is still on the dashboard. I've tried reading the codes, but get nothing.
When i move the roof switch back, with the windows open, it tries to pop the hardtop up... the only section not to raise is the front passenger side. I've tried doing this with the engine running in case the battery is low.
I'm trying to get my hands on the tools to remove the hard top manually.
Any ideas anyone??

*Problem Resolved*
Took the car (with the new 2nd-hand roof ECU) to Cayman Auto Services in Dorking at the weekend - he read all the codes and re-sync the windows. Finally the roof now works! Just in time for the snow to arrive!

Just need to get the rear coil spring sorted & the front bearing re-greased, then i can fold away my cheque book for a while...

I would be more than happy to share my experience with anyone that has a similar issue. One thing i'm still not clear on however, is reading the codes. I followed all the instructions, but i was obviously not doing something correctly, as the indie was able to sorted it...

What would be very useful; is if someone could video how to read the codes and post it on YouTube.

no window synch needed on a '91, comment on top alignment
 

AGod,

congratulations! I am curious what the shop actually read in the codes and what they did to make it work. The windows do not need to be synched on a '91, but the shop apparently did something else that makes your top work. Do you know which codes they found?

Window synchronization is needed only on model years '95 and up.

If the front passenger side did not pop open on the hard top, then that means the latch on that side had a harder time opening. By the way, it is usually harder for the system to lock and unlock the hardtop, because it normally seals tighter, and it may be misaligned coming off a different car. Both front latches get hydraulic pressure at the same time. Has anyone checked the hydraulic fluid level?

It could be that the system has a hard time opening the front latch because there is a serious need for lubrication in the part that receives the prong from the top, or the prongs on the hard top need alignment (especially if it came off another car). Moving the prongs back pushes the top forward onto the windshield header seals and creates more tension (but seals better), and pushing the prongs forward results in less tension and makes the job easier for the latches. You want to balance both sides to work equally well, have the top waterproof, and tight enough not to rattle. It takes a star wrench to loosen the prongs.

-Klaus

klaus@tophydraulicsinc.com

Thanks for your detailed info Klaus!


The indie did the following: Read the fault codes, which advised that the roof was out of sync - in otherwords the car didn't know what position the roof was in. By clearing the codes the indie was able to start the cycle again and the hydraulic roof popped up no problem. He didn't mention the need to adjust the front roof latch. I had checked that the hydraulic fluid was at max.

I removed the hard top and tried out the soft top the next day with no proplem. I will adjust and lubricate the prongs once i obtain a wrench and the weather is nicer! :)

I have same problem with my 01 SL600.

What codes were read, and what is Indie?

Joe B.

In the world of older cars, there are dealers with high prices ("stealers" ) and Independent mechanics ( "indie or indy" ) that have great skills but not always the high prices!

Thanks; still have the problem.

Joe B.:)

revisiting this issue again on my '97.. roll bar light and roof switch light are on all the time. and no joy pushing buttons... going to revisit the process that TopHydraulics suggested in another thread a couple weeks ago. I had taken the car to a MB shop and they got the lights out and the top up. let it stay up a couple weeks to stretch out (NEW TOP) it went down fine, but went into error mode the first time I tried to put the top back up. the front didn't latch down all the way and the rear cover started dancing up and down. Had never seen that one before.. the rear half of the top never was able to lower.

I have similar problems with my 1996 sl500. I don't have the top/rear hatch opening tools either. I just use a torx driver and a flat wrench. After repairing the power window brushes my windows work but the quarter inch raise/lower automatic feature only works on one side. I think I need a new top module as my top and roll bar don't work either. How do you get the codes to come up and where did you find a code chart? Thanks for now, Joe.

Do have a photo of where the roof ECU is?

Roll bar switch flashes
 

I have a '97 SL320. Electronic control module seems to be problem since top won't go up or down and top up/down switch and roll switch stay lit all the time.I had a mechanic try a new ECM and every thing worked fine except the roll bar switch continued to stay flashing after top was up or down and roll bar was down and in place. What would cause the roll bar up/down switch to stay lit or flashing once everything else seems to be working?

Top fixed
 

93 500SL

https://lh5.googleusercontent.com/-a...0/100_1393.JPG

Top switch was flashing also ASR/ABS light was on.
Replaced blown fuse on ABS ECU and brake pedal switch.
Now all is working properly.

I didn't take it to a shop for DTCs.
Just pulled and cleared codes with a simple 3 wire $40 LED switch off of eBay. :y

can i use Brake-fluid ?
 

In an emergency, can I use brake-fluid to fill the roof resevoir to operate the roof?

Why not just get a can of Pentosin CHF11S?
It's just the same as the Mercedes Q-1-32-0001 stuff but cost less.

http://www.minicarparts.net/product/....0.148.132.jpg

I'll never be mistaken for a scientist, but the thought of mixing 2 liquids of different viscositys with an unknown impact on the very expensive hydraulic system & seals could be disastrous; as in potentially 'eating' the cylinder seals.

I also dont know about the Petosin brand mentioned above. What I can say through experience is the in addition to MB branded fluid, Febi/Bistein Fluid, p/n 02615 is the same material as MB in all specs except color. Febi is the OEM of MB's fluid and I've had it in my system for the last 4 years. I carry a bottle of the fluid in the trunk of my car; the cost is approx. $15 last time I looked.

I just checked autohauasaz 's website, https://www.autohausaz.com/search/pr...ension%20Fluid

The Febi brand is approx. $11/bottle; MB branded around $16

Pentosin CHF-11S
 

MercBimmerman,

thanks for your input. Although Mercedes Q1320001 is not the specified fluid for the R129 top hydraulic system, I believe it would be okay.

CHF-11S is actually specified for some other brands' top hydraulic systems which are basically using the same combination of alloys, steel, hoses and seals. It looks like the viscosity is almost the same as Febi 02615's.

Here is what's important for top hydraulic system fluid, and Q1320001/CHF-11S fit the bill:
- no additives that would make the seals swell up
- fairly consistent, low viscosity over a wide temperature range
- no emulsifiers
- mild rust inhibitors

As Bob points out, Mercedes 0009899103 and FeBi 02615 are actually cheaper. Also, I have heard that Napa can supply FeBi 02615, although they don't normally have it on the shelf.

Klaus

www.tophydraulicsinc.com

Why brake fluid is a break-fluid for the top hydraulic sytem
 

Chris,

It's a good thing that you asked. In a nutshell, adding break fluid is bad for the system. DOT 3 and DOT 4 brake fluids dissolve residual water on the bottom of the reservoir. Water kills the OEM rod seals in all top hydraulic cylinders and those used by some esteemed competition of ours within about a year. Top Hydraulics' seals do okay with water in the system, but that's beyond the point I am trying to make. I am attaching some photos of water-decayed seals below. The decay with water involved makes the seals crumble in sizes that can block the valves and just about drive most mechanics crazy.

DOT 5 brake fluid does not dissolve water, but easily forms a gooey sludge in the system.

Please stick with the recommended fluids or move and lock the system manually until you are able to deal with hydraulic leaks in your top. See http://www.tophydraulicsinc.com/maunuallockhardtop.pdf for locking and manual operation of soft tops and hard tops in various model years.

Klaus

www.tophydraulicsinc.com