cqae

Hi everyone, I'm looking for some help with my CLK with a roof that wont work.

Basically, when I try to open it, everything seems to be going ok, compartment opens, rear window folds up, but as the front of the roof tries to open it stops, the light begins to flash & its no go from there. If I scan it, it gives me a code b1650-limit switch not plausible.

If when I am trying to open the roof, I help it along, it opens up & at about the halfway mark will start to pull the roof up,. but it seems very weak & is easily stopped by hand. It eventually fully opens but you kind of have to tuck the roof into its compartment, its like it isnt fully in there. The the rear compartment cover dosnt close either, but with a little help it will lower but not lock.

However, if I try to close the roof, it all works fine & any attempts to stop it is quite hard, the roof closes very strongly & everything locks perfectly.

using my scan tool, I was locking at the function of s84/11 which is the switch in the windshield-it seems to work perfectly as I lock & unlock the latch, but seems to go to locked as the roof opens.....I can actualy move the roof by hand a few inches & get it to change to locked? really cant see how this happens when I'm not moving the windscreen at all?

anyone seen this & have anything to share & help here?

GatorMB

Strange but have you checked the manual bleed screw for leakage. Try loosen and re seat a couple of times.
Valving in the top control system might be at fault. By the way never heard of this but many have left the manual bleed screw loosely seated.

ItalianJoe1

Coworker had a similar one a couple days ago, the tensioning cables in the top were weak and needed to be replaced. He also had limit switch codes but the same issues, it would work with a little assistance by hand at one point, and fully powered the other direction with no issues.

GatorMB

I have been using the top with a helping hand since ownership, I have a long arm though.
I posted the cable numbers and a link to a helpful guide in a long winded post in this forum.
Once the hydraulics start acting up it it is time to consult with Klaus Tophydraulicsinc.com

Cheers

cqae

thanks for you advice guys. I have had a crazy week & havent gotten back onto this problem. I am not sure how the cables would affect it in the first 6-10 inches of moevemnt but will need to go and check them closer as I have read they are common to stretch or break. can they easily be viewed without pulling too much of the roof apart?

cqae

Ive done a little more playing with this one guys & am really stuck & desperate for some help. Essentially, the roof stop as soon as it tries to raise the front section near the windshield. Its like it lacks the strength to pull the roof up. This is where I am stuck. Is there 1 cylinder that is responsible for this or 2 they all work in combination? the cylinder on the left hand side is showing some signs of leakage, but this is fairly minor & I dont think it would be stopping it from working?

I dont mind replacing it, but want to get the diagnosis right......

It all seems ok when closing though

Serndipity

After you unlock the front bow, the purpose of the tension cables is to open up the joints of the roof's frame, as shown in the enclosed picture.

If the joints do not open, the hydraulics will not be able to open the roof.

The cables run between the front bow and to a point further back on on the roof frame. When the roof is partially open, the rear attachment point will be exposed and you will be able to determine if the cables are broken.

This thread has additional details https://mbworld.org/forums/clk-class...-problems.html

cqae

The cables definitely aren't broken. And I thought the only helped the start part of the lift. Even if I manually assist the roof in this first stage it doesn't take over and do it by itself.

Its like the cylinders simply aren't strong enough at any stage of the opening process but close is ok. I was thinking the 2 lift cylinders have failed and one is definitely leaking. Is there any possibility of this?

i was thinking the pump would be ok as it closes perfectly

Serndipity

Yes, if the frame is properly opening, as shown in the picture, the hydraulics should be able to continue opening the roof.

When the soft top does not open or only raises slowly, the possible causes can be due to a malfunctioning:

Soft top fabric bow up/down limit switch (S84/15)
Power top valve block (Y56/2)
Hydraulic cylinder, open/close soft top (left or/and right)

You mentioned a couple of clues, the hydraulics close the top normally and only the opening the top is not working properly, as well as at least 1 leaking hydraulic cylinder.

In order to provide 2 way motion, the power roof uses differential hydraulic cylinders. When a side of a hydraulic cylinder is pressurized, it's rod extends or retracts and the direction of motion depends on whether the pressure is applied to the rod or piston side, by the valve block. Additionally, when pressurized on both sides, the cylinder rod extends, because the force acting on the piston side is greater, due to the larger area.

To accomplish this, in addition to port seals, both the valve block and cylinders also have internal seals and unfortunately, with age, they deteriorate and leak. Fortunately, as already suggested by GatorMB, they can be economically rebuilt.

You'll find more information and DIY instructionals here https://www.tophydraulicsinc.com/en/...benz-a208-info

cqae

Thanks for your detailed reply

i think you you are right and I'm leaning towards replacing both top lift cylinders. I've spoken to Klaus at top hydraulics and will try them and let you guys know.

Im thinking that because the roof closes the pump is ok. I've tried swapping solenoids on the pump and it didn't change the issue so I think that rules them out.

I'll get them installed and see how it goes. Thank you!

cqae

ok bad news for me, the lift cylinders didnt solve my issue, I was hoping someone else may have some ideas? something that ,may be worth noting, when we close the roof you can hear the pump 'load up'..I mean its spinning & as it begins to move the roof you hear the pitch change as it begins to lift. when opening it, its spinning along but there is no real change in the sound as it begins to open the roof.......

I'm thinking the valve body may not be holding its pressure. Is there anything I can do to test this, because I have already replaced the cylinders I just want to rule out as much as I can before I spend more money.

Also, I understand we need to hold pressure to lift the roof, is there anywhere else that we could be losing pressure?....All the other functions as far as I can tell are working so was thinking its only the pump left.......

Thanks in advance!

Serndipity

Before trouble shooting additional power roof components, after changing a hydraulic cylinder, here are a couple of suggestions.

Make sure the screw, used to reduce hydraulic system pressure, to make the repair, has been turned back, to restore full pressure.

Also, the roof's position/limit switches may cyclically be miss-set and the system needs to be re-synchronized. Note: The left side cylinder you replaced includes a switch. This is done by manually, fully opening and closing the roof. The detailed procedure is described in the practical hints section of the owners manual.

No guarantee that one or both will restore your power roof operation, but there are many cases, where after replacing a cylinder, it did.

cqae

I didnt actually open the release valve to replace the cylinders so I know its closed-I've rechecked it too.

There was no switch on either cylinder in my case, both were in the same area, but neither need to be touched to replace the cylinders.

It has also been folded and opened manually numerous times after the cylinders were installed & oil levels checked & rechecked.

Im pretty certain its not a switch or reset issue as the roof makes an attempt to open. Its as if its just not strong enough then sets codes & stops trying. I'm thinking its a hydraulic bypass somewhere but dont know where exactly. Is there anyway of ruling particular cylinders out so I can confirm this before I buy a replacment?

Serndipity

Back in post #3, it was suggested that when the soft top does not open or only raises slowly, the possible causes can be due to a malfunctioning:

Soft top fabric bow up/down limit switch (S84/15)
Power top valve block (Y56/2)
Hydraulic cylinder, open/close soft top (left or/and right)

The Up/Down rear bow limit switch (S84/15) is attached to one of the rear bow cylinders, not the top's drive (i.e. lift) cylinders you found leaking and have since replaced.

Additionally, the power top valve block (Y56/2), should have also suggested as a possible cause, actuation of soft top "open" valve (Y56/2y1). Note: Faulty actuation could be electrical (i.e. solenoid/wiring?) or when actuated, the internal seals have deteriorated, such that the valve block channeling is not supplying the necessary hydraulic pressure to lift the roof. Klaus, at Top Hydraulics, would be the the go to guy to discuss this further.

Following are some additional thoughts that might prove helpful, should additional trouble shooting may be required.

In regard to your question regarding ruling out particular cylinders. By far, the rear bow lock and/or the case cover lock cylinders have been the most common ones that frequently leak. They can be easily inspected by removing the carpeting inside the soft top compartment cover. Also, due the flexing at the cover hinge, check the hydraulic lines and wiring harness for breakage.

Most of the issues with the S84/15 switch have been due to it's fastening onto the cylinder becoming undone, such that no longer is properly actuated.

In regard to your scan tool giving you a DTC code, B1650-limit switch not plausible. This only indicates that the positions of the limit switches do not correspond to the roof's cyclical sequence or are unknown. The MB STAR SDS tool would further break the DTC into 12 additional codes (e.g. from B1650-00 to B1650-12), that point to a particular switch. I have enclosed some thumbnails, that show the stages of the roof, as it opens, along with a chart that shows the corresponding actuation details for each limit switch and valve solenoid, at that point in time (e.g. kind of a poor mans version the MB STAR SDS DTCs). A MB tech would then proceed to troubleshoot at the N52 connector, which has all required input and output signals present, excepting those to/from the CANBus . Note: the outputs are voltages and you would need a special connector block to make electrical contact beyond the wiring insulation. However, all the inputs can be easier to verified, by disconnecting the N52 connector and with a multi-meter, measuring the ohms, from a specific pin to vehicle ground or in some cases, between to pins (e.g. a reading near 0 ohms indicates the switch is closed and a reading greater than 20K ohms indicates that the switch is open, as required during the stages of roof operation). This will also check the wiring between the switch and the controller, as well. I can provide additional details if you need to do this.

BTW, if your Y56/2y1 where faulty due to an electrical problem, assuming your scan tool is capable, you would have found a BI647-I7 diagnostic trouble code. This DTC triggers if the electrical current in soft top "open" valve block solenoid (Y56/2y1) is to low or to high, which would require additional electrical troubleshooting. If to low, either the N52 controller is not providing the current, the solenoid coil has become an open circuit, or there is an open circuit in the wiring harness wiring. If to high, it's a short circuit in the wiring harness.

The DTC's are all based on electrical conditions (READ: they do not specifically relate to the condition of valve block or cylinder internal malfunctions, such as bad seals etc). As example, the B1650 DTCs are triggered, by a watch dog timer, when the maximum permissible time for a specific limit switch to actuate, has been exceeded.

cqae

I haven't actually been focusing on the fault codes. When I help the roof by hand they dont log. Which to me indicate the system is electrically ok. I feel there is a hydraulic failure, so when it tries to lift the roof, the system logs these codes because it knows the roof didnt open by the switches......
I will inspect the rear bow lock & case cover cylinders tomorrow. I dont think they will be leaking as the fluid level has never been low & there is no oil stains that I can see, but I have a look anyway.

What I am wondering is: can a cylinder leak internally & vent the pressure off? I was thinking that when the pump attempts to pressure up the 2 lift cylinders that the pressure may be leaking internally at another cylinder & this may be causing my fault.

If so is there any way to check this?

Ive spoken to klaus via email & he has suggested as you did that bow & cover latch cylinders can fail & these get pressurized when the roof is moving. is there anyway I can bypass them to check if they are at fault?

and finally serndipity....thanks so much for your time & efforts in helping me, I appreciate it so much!

Serndipity

[QUOTE] I haven't actually been focusing on the fault codes. When I help the roof by hand they dont log. Which to me indicate the system is electrically ok. I feel there is a hydraulic failure, so when it tries to lift the roof, the system logs these codes because it knows the roof didnt open by the switches...... [QUOTE]

When you operate the roof manually, you are not using the controller, therefore no DTCs will be stored.

However, when using the power roof controller to operate the roof, as explained at the end of my my last note........

All of the diagnostic trouble codes (DTC's) are based on electrical conditions, monitoring the N52 controller's input and output signals, based on voltage, resistance or time measurements. As example, the B1650 DTCs are all triggered and stored, by a watch dog timer, when the maximum permissible time for a specific limit switch to actuate, has been exceeded. Also if a DTC in the B1647 group (e.g. between B1647-10 and B1647-18 ) is stored, it indicates that the current in a particular valve block solenoid is to low or to high, which would require additional electrical troubleshooting. If to low, either the N52 controller is not providing the output voltage signal, the solenoid coil has become an open circuit, or there is an open circuit in the wiring harness wiring. If to high, it's a short circuit in the wiring harness.

Other then this, there are no DTCs that specifically relate to any internal malfunctions (e.g. condition and/or functionality) within the pump valve block or the 8 cylinders (e.g. inadequate pressure, deteriorated leaking seals etc).

[QUOTE] What I am wondering is: can a cylinder leak internally & vent the pressure off? I was thinking that when the pump attempts to pressure up the 2 lift cylinders that the pressure may be leaking internally at another cylinder & this may be causing my fault.
If so is there any way to check this? [QUOTE]

The pump in hydraulic unit (A7/5) generates the required operating pressure and hydraulic cylinders actuate the mechanics of the soft top. There are a total of 7 hydraulic cylinders installed:

Hydraulic cylinder - open/close soft top, left
Hydraulic cylinder - open/close soft top, right
Hydraulic cylinder - lift/lower soft top bow, left
Hydraulic cylinder - lift/lower soft top bow, right
Hydraulic cylinder - unlock/lock soft top bow
Hydraulic cylinder - open/close soft top compartment cover
Hydraulic cylinder - unlock/lock soft top compartment cover

The soft-top system is controlled by the control module (N52), which analyzes the positions of the position/limit operating switches and correspondingly switches the solenoid valves (Y56/2y1.....Y56/y7) to actuate the hydraulic cylinders.

As noted in post # above, in order to provide 2 way motion, the power roof uses differential hydraulic cylinders. When a side of a hydraulic cylinder is pressurized, it's rod extends or retracts and the direction of motion depends on whether the pressure is applied to the rod or piston side, by the valve block. Additionally, when pressurized on both sides, the cylinder rod extends, because the force acting on the piston side is greater, due to the larger area. To accomplish this, in addition to port seals (O rings), both the valve block and cylinders also have internal seals (cup shaped) and unfortunately, with age, they deteriorate and internal and/or external leak occurs. As a FYI, I've enclosed a thumbnail that explains how the lift cylinders both open and close the roof.

Hydraulics are above my pay grade, but basically, inside the valve body is a structure of channels (e.g. maze like). The direction of hydraulic fluid flow, is determined by specific solenoid activations, which will opens and/or closes paths in the maze, thus supplying the necessary rod or piston side pressure to the cylinders. Note: From what you have said, your soft top has trouble opening, which is controlled by the soft top "open" solenoid valve (Y56/2y1), yet closes normally, which is controlled by the soft top "close" solenoid valve (Y56/2y2).

When someone brings their car to a dealership, with a power roof issue, the first thing they would do to diagnose the problem is connect the STAR SDS system to see there are any stored DTCs. That service alone will cost around $150 and you can leave with a printout. If they proceed to the troubleshooting stage, it can become quite expensive, because it requires disassembly of panels for access to the N52 connector, setting up the various roof configurations to test the electricals, which may lead to some dead ends (e.g. chasing down a B1650 DTC, for which there are specific procedures to troubleshoot each switch, but was only triggered by a watch dog timeout).

If a correct diagnosis is not possible at this time and to answer your question in regard to specifically testing the hydraulics, there are a couple of additional troubleshooting procedures. They require specific setup procedures, specialized tools and are somewhat limited in scope.

First they will test the system pressure and if not correct, perform a visual inspection for external leaks. If none found, the next test will check for internal leaks in the hydraulic cylinder, unlock/lock soft top bow, which requires a significant test setup (e.g. positioning of the roof components, disconnecting the cylinder return line and plugging the port) and reading the pressure. If not as specified, indicates an internal leak, if as expected, the third test will test for internal leaks in the hydraulic cylinder, unlock/lock soft top
compartment cover, which requires a significant setup procedure, to read the pressure. If not as specified, indicates an internal leak, if as expected, suggests an issue with the roll-bar system.

Eventually, you'll get a correct diagnosis and repair cost of $$$$$$$$.

Some examples:

The roll-bar system has a small valve block, a single hydraulic cylinder and 2 limit switches. Dealer estimate to repair was $7,000, but owner did a DIY repair at a cost of about $25!

Details here https://mbworld.org/forums/clk-class...ar-switch.html

New hydraulic pumps are no longer available from MB. Dealer price for a rebuilt unit was $3,200.

Details here http://www.benzworld.org/forums/c208...p-rebuild.html

Go figure!!!!!

cqae

thanks so much for your detailed reply! Ive spent some time doing some more playing with this today, but still havent gotten any further.

I think I may have confused things too. When I said I was opening the roof manually & it didnt log any codes I meant I was helping it while operating the switch. SO the controller is still attempting to do everything it needs to do.

Basically I feel electrically everything is ok. When the roof gets to the stage where it lifts the front, after it has raisd the rear compartment lid & rear bow, it attempts to lift the front of the roof, you can see the roof move just a little then the system logs a code & kinda trips out & stops working. Cycling the ignition brings it back but it will just do the same thing. If i help lift it during this stage it will go through its motion but can barely move the roof & even onces its nearly folded into the compartment cant pull it in enough to fit it in there.

I was thinking one of the other cylinders may be leaking internally & bypassing pressure, so I've pulled the hoses of each cylinder, checked which one spurts fluid out during that motion of roof movement & blocked it off by plugging it into one of the old lift cylinders & it hasn't made any difference.

So I feel its a failed pump now. Either a solenoid isn't closing properly, or the pump just isn't building up enough pressure to lift the roof. I just thought this unlikely as it operate all the other cylinders easily, but clearly this is the hardest part to lift.

Have you ever heard of a pump failing and just not being able to lift the roof?

Serndipity

The basis of all the B1650 DTCs is a watch dog timer in the controller. When the maximum permissible time for a specific limit switch to actuate has been exceeded, a DTC is triggered and stored.

When the roof is being manually operated, the controller is not in operating, so no DTCs will register.

When you assisted the hydraulics, when opening the roof, you got no DTCs, because you beat the timeout limits.


[/QUOTE] So I feel its a failed pump now. Either a solenoid isn't closing properly, or the pump just isn't building up enough pressure to lift the roof. I just thought this unlikely as it operate all the other cylinders easily, but clearly this is the hardest part to lift.
Have you ever heard of a pump failing and just not being able to lift the roof?[/QUOTE]


The power roof is extremely complex (e.g. a 'convertible' forum search will show more than 500 results). The good news is that, this has provided a tremendous goldmine of of DIY diagnosis/troubleshooting/inexpensive repairs.

Most of the problems with the hydraulic pump unit, have been with the pump motor, due is failing to turn on, or having burnt out. Neither apply to your situation, because your pump operates correctly, except when lowering the roof.

When the controller calls for the pump to operate, it sends a low current electrical signal to a relay coil, which then opens or closes contacts in the the relay, that supplies the high current (e.g. 30 amperes), required to run the motor. When the relay contacts make/break the high current circuit, an arc (i.e. spark) occurs, which over time causes sufficient contact pitting, where the relay will not pass the necessary current to start motor. That's if your lucky, because sometimes the failure mode, is the contacts welding together, which causes the motor to run continuously and burn out. The pump relay is an ubiquitous, inexpensive part (e.g. same as the one powering the fuel pump) and easily replaceable (e.g. plugs into a connector). I strongly suggest that you replace it, as preventive maintenance, while you have the access panel to the pump area, removed. I included this one http://www.autohausaz.com/search/pro...%20Top%20Relay with a parts order for other maintenance items, just to have on hand, should my power roof ever fail. It's an OEM part (e.g. box doesn't come with the MB logo), but you will be able to pick up a comparable relay at your local parts supply store, as well.

Additionally, the pump motor is not rated for continuous duty and will burn out, if run to long. To prevent this, the controller has several builtin safe guards. If the main switch is held up to long, the controller has is a of 250 second watch timeout, to stop the pump motor. Additionally, the motor also has a thermo-couple which should shut off the motor, if it gets to hot, such as might occur upon repeatably running the pump, without sufficient periods of cool down.

As the Mercedes ads say....."The best, or nothing".

If you read the last link in post #16, where Klaus explains the details of the Top Hydraulics pump rebuild service, it also includes upgraded electrical components (e.g. a new relay as well as a thermo-couple with improved temperature characteristics to keep the motor from burning out).


[/QUOTE] Basically I feel electrically everything is ok. When the roof gets to the stage where it lifts the front, after it has raisd the rear compartment lid & rear bow, it attempts to lift the front of the roof, you can see the roof move just a little then the system logs a code & kinda trips out & stops working. If i help lift it during this stage it will go through its motion but can barely move the roof & even onces its nearly folded into the compartment cant pull it in enough to fit it in there. [/QUOTE]

When the soft top does not open or only raises slowly, the possible causes are:


- the open/close soft top (left or/and right) hydraulic lift cylinder
- the rear fabric bow up/down limit switch (S84/15)
- the power top valve block Y56/2, usually the soft top "open" solenoid valve (Y56/2y1)

So far, you have found and have replaced your leaking lift cylinders, which very likely was contributing to your roof opening problem, but was apparently not the sole issue.

As shown in an enclosed picture, the S84/15 switch is associated with the left rear bow up/down cylinder. The switch is shown unattached in the picture, but it actually fastens (clips?) onto the cylinder and is actuated as the cylinder extends or retracts. Also enclosed is a functional description of the rear bow cylinders, which shows the switch attached, but unfortunately, does not cover the purpose of the switch.

I'm enclosing two thumbnails that were included in post #14. They depict the key stages during soft top opening operation, along with the corresponding states of all the required position/limit switch and solenoid valve actuations. As mentioned in the post, these are what a MB Tech would use to further troubleshoot the electrical signals, at the controller's N52 connector and even a shade tree mechanic could verify that a switch is actuated, or not, at a specific stage, by disconnecting connector and with a multi-meter, measuring the ohms between the appropriate connector pin and vehicle ground.

Also, read the first page in this thread https://mbworld.org/forums/clk-class...-failures.html . In summary, after replacing a leaking rear bow lock cylinder, his power roof was still inoperative. Then paid dealer $330 to diagnose, which resulted in a repair estimate of $1,450. In addition to the There was an additional problem preventing his roof from operating, which was the S84/15 switch on the rear bow up/down cylinders, that he DIY repaired.

BTW, sometimes the S85/15 has been known to not actuate properly, because it's positioning on the cylinder is out of kilter. Also, carefully visually inspect all the hydraulic lines and electrical wiring (e.g. for kinks, being pinched, breakage) in areas where they a subject to movement.

[/QUOTE] I was thinking one of the other cylinders may be leaking internally & bypassing pressure, so I've pulled the hoses of each cylinder, checked which one spurts fluid out during that motion of roof movement & blocked it off by plugging it into one of the old lift cylinders & it hasn't made any difference. [/QUOTE]

I'm thinking more, possible issues within the valve block (e.g. solenoids, check valve, internal seals etc.). Klaus would be the go to person on this.

GatorMB

Well Put Serndipity,
Watch dog circuits are in place to protect machinery and electronics in many industries.
Hence Limp Mode on the Engine management systems.

The only other strange but true phenomena we cannot see is the mechanical condition of the roofs skeleton. If the car is from or lives in a salt air environment there could be frozen or broken mechanical parts in the frame of the top. Where is the car from and now located?
Never read about one degrading this bad but did recently come across a CLK430 cab with 45,000 miles found parked under an oak tree.
A real test would be connection of pressure gauges to the pump and cylinder circuits but the min/max pressure specifications are required as well.
There are not many with this kind of tooling though. A used or borrowed pump might be an alternative.

If the pump is weak the motor will work double duty but eventually go into thermal overload and shut down. The same will happen with a porous or pitted relay as it degrades the motor rpm, increases current demand and overheats. The relay without diode for testing only are around 5- at the local auto parts.

Cheers

cqae

wow, you guys are awesome, thanks so much for taking the time to write such detailed & informative replies. I'm going to get a bit further on this one today, but thought I would reply now while I have the time.

Firstly, I hadn't mentioned it, but the relay has been replaced. When I first started looking at the fault, it was completely inoperative & the pump wouldn't spin at all. I replaced it & thats where we found the current issues.

AS far as the switches, I have a scan tool & have checked them all both with the scan tool & with a multimeter at the controller & they are working too. They are all switching at the times the table tells them to. I am going to recheck those today.

AS far as the watchdog timer-thats exactly what is happening when I manually assist the roof. However I feel that while it triggers this fault, its not making it from one switch to the next switch in the allowed time, and by me manually helping it, it is making it.

According to the table this is stage 8, which is the final part of opening the roof, but it fails at the very start, the roof just moves a tiny bit-really nothing at all then it triggers the code & stops moving until the ignition is cycled. Something of note-when I manually help the roof at no stage does the system really take over, even once the roof is folded up inside the rear compartment, & its like it hasnt squashed it down in there far enough too.

Ive been having a good think about it over the weekend & basically am thinking that at the beginning of stage 8 all the switches must be ok or it wouldn't attempt to start stage 8 but triggers teh fault as the next switch wasnt reached. I'll get back into it today & see what else I can find

Serndipity

Hi GatorMB.....nice to hear from another cabriolet owner and forum veteran.

IMHO, the W208 has been one of the best MB built in the last 25 years. Both the M112/M113 engines and 722.6xxx transmissions have been pretty much bullet proof.

However, as they continue to age, expect more and more electrical, as well as power roof issues.

As you mentioned, when the transmission goes into 2nd gear limp home mode, it's to protect it's self from potential mechanical damage and 99.99% of the time, it's an fault in one of the 3 electrical control units (e.g. shift control, transmission/ECU control, or conductor plate) and 99% of the time, all of which were owner preventable.

Back to the OP.......

I very much doubt that it's a frame issue because:

- it struggles only when opening and otherwise operates normally (e.g. when closing)
- the hydraulic lift cylinders will struggle, after unlocking the roof, if the joint shown in post #7, does not open

Additionally, my MY2001 cabriolet, has spent it's entire life, within 100 feet, of the Atlantic ocean shoreline, w/o a problem.

Note: Unfortunately, most of my brass/chrome plated household fixtures can't make the same claim.

Back in post #15, I touched on, if all the electrical tests proved OK, there are a couple of hydraulic tests, that a qualified MB Tech could do, which is well beyond the capability of DIY.

Specifically, checking the pump's output and system pressure, which should be 150 bars, only requires minimal knowledge and just a pressure gauge. The 2 other test, to test the rear bow and/or case cover closure/locking is much more complex (e.g. involves adapters, plugs, specific set-ups etc.), well beyond DIY.

Because the power roof, otherwise operates normally, to a degree (e.g. excepting the valve block solenoids) rules out the pump.

After the OP replaced the leaking lift cylinders, next up would be either the S84/15 switch or solenoid valve (Y56/2y1).

I've suggested some troubleshooting thoughts to confirm that the S84/15 is performing correctly.......because it's not that difficult to do.

cqae

I forgot to respond to Gator too, i also doubt its a frame issue as it moves freely when manually pushed/operated. While i know the pump must be ok, I was thinking the valve body thats a part of it

I'll get onto rechecking the s84/15 later today but was pretty sure I checked it a few weeks ago, just want to 100% rule it out

Serndipity

cqae......thank you for your last note and the additional information.

Of the 3 possibilities for your roof snuggling to open, I've focused on the S84/15, roll bar 'up/down' switch, because after replacing your leaking lift cylinders, it's the most easy to troubleshoot (e.g. if it's operation is confirmed, next up would be the pump's valve block).

I reviewed the stages of operation vs. the inputs and outputs of the N52 controller. Specifically, during the 1st 4 stages (e.g. from 0 to 3) it's active (e.g. dealing with rear bow/case cover issues), then goes into a indeterminate state during stages 4 - 6, thereafter again turning active in stages 8 through 11. Note: during stages 8 through 10, the switch activates Y56/2y1.

In my prior note, that included the thumbnail of rear bow cylinder purpose/operation, of which the S84/15 is attached......the purpose of the switch, was not discussed, which at the time, baffled me.

Since then, I've looked the the electrical schematic diagram of the power roof controller, from which I believe I figured it out. FYI, see the .pdf diagram enclosed.

The switch is multi-purpose, depending on the open/close signals it presents to pins 11 or 13, at the N52 controller. In one instance, it notifies the controller that the rear bow has lowered, allowing the controller to proceed with the locking the compartment cover and rear bow. In the other, it actuates the Y56/2ya1 valve solenoid, that should supply the necessary pressure to open the roof.

How is this possible?

Physically, at one end, the switch clips onto the piston section of the cylinder body and at the other end, onto a screw like protrusion, at the end of the cylinder rod.

When the cylinder rod retracts, the controller goes about it's business of locking the bow/case cover. When the rod extends, the controller activates the valve block solenoid, that actuates the lift cylinders.

By inspection, of the aforementioned switch attachment mechanisms, will at least provide solid odds that the switch is performing as designed.

Otherwise, for 100% confirmation, you'll need the check the N52 pins with a multi-meter or use a scan tool that is capable of breaking down the broad B1650 code, delineating where the 1st occurrence DTC (e.g. MB STAR SDS).

GatorMB

When working with pressurized hydraulic systems please wear eye protection and never let it penetrate skin.
Some is highly toxic. putting your finger over a high pressure port to test flow could result in an infected and or lost limb.
Just be safe

cqae

ok, so I dived back into this this afternoon & made some further progress. Ive checked switch s84/15 which is in the left hand 1/4 panel on the bow lift cylinder. Its doing as it should, grounding a wire when the bow is in the up or down position. Also in there is another switch that signals if the the front of roof open of closed position. Both of these check ok, so I am happy to rule them out & move on.

I also considered the controller holding on a solenoid incorrectly & have ruled this out by checking for voltage changes on each solenoid. Basically all go to ground & the controller applies voltage to trigger each solenoid as needed. I have just checked that each solenoid changes at some stage as I while I thought it possible that it isn't controlling a solenoid, I dont feel it would trigger one at the wrong time. All solenoids change state at some point. I dont think I mentioned it, but all solenoids were swapped into different positions& feel if there was a fault in one, the symptoms I'm having would of changed

So this leads me to believe I have a fault in the valve body of the pump. I really don't know what else it could be & am thinking this is the next step.....I hope you guys agree