So as the title suggests, My CLK55's top isn't working. I get the slow blink from the switch when trying to lower the top. The windows do go down but after that, nothing.

With the help of an SDS and a friend, I was able to determine that the car knows when the bow is locked and unlocked, when the cover is open, locked, but strangely not closed.

This is tracked down to switch group A25 s1 (closed) & s2 (locked).

The test info using the tester block / cables (which I don't have) that plug into the controller harness / controller N52 call for a 0-1 V reading for closed and 11-14 V when open. If both values aren't met then the possible cause is the N52 controller being bad. If only one, then it says to check the resistance. In most cases it points to either a bad switch (s1), wiring, or a controller.

Question 1:
Does any one know how to test for these voltages without the testing block etc.

Question 2:
Does anyone know what part number A25s1 is to replace? I can't seem to find it despite all of the googling in the world.

TIA

 

WDBLK74G72T115718

 

Hello fixedhalo....it seems that you're well on your way to repairing your power roof. I hope that you'll find the following comments helpful.

Beginning in MY 2001, MB made a raft of upgrades to the W208 (e.g. Bosch ME 2.8 engine management and revamped engine electronics, spill resistant shift module, led directional blinkers in the side mirrors, higher flowing injectors, larger throttle body on the 430s etc.). With respect to the A208 cabriolets, from VIN 070018, there were significant upgrades to the power roof system, which included a different controller, pump valve body, soft top compartment cover lock switch group etc..

As a result, there are two important cautions. The first is that many of the power roof components, between early and late production, have different part numbers and are not interchangeable. For example, the earlier valve body had 7 solenoids (w/ 9 electrical connections to the controller), while the updated one has only 5 solenoids (w/ only 7 connections), which is my other caution. There is a lot of documentation floating around on the web, that is outdated. For example, I've seen a copy of a 1999 soft top diagnostic manual, that in part could be helpful in repairing a later model A208, but can not be relied upon for diagnosis/troubleshooting procedures and/or details. BTW, the 1st year of production for the CLK55 cabriolet was MY2002.

From your description, when connected to SDS, the DTC stored was B1650 07, indicating that the maximum permissible time, for the soft top cover closed switch (A25s1) to actuate, had been exceeded. Your current troubleshooting involved 2 questions.

Question 1: Does any one know how to test for these voltages without the testing block etc.

As you mentioned, testing the voltage values, with the soft top compartment cover closed and then open, is basically an initial verification that the controller has voltage supply and correct signal levels. However, the ignition needs to be on and the controller connector in place. However, the multi-meter must have access to the conductor inside the wire, which requires the special test block. BTW, the MSRP of the test block is around $2,600! FWIW, voltage supply to the controller is via 3 fused circuits.

Performing the resistance test you mentioned, will verify that the A25s1 micro-switch properly actuates when the cover is closed. The test block is not needed and can be done by just disconnecting the controller connector plug and checking it's ohms resistance, at the with the cover opened and closed, at the 'top cover closed' pin on the plug. As of May 2000, that would be pin #47.


Question 2: Does anyone know what part number A25s1 is to replace? I can't seem to find it despite all of the googling in the world.

You need to google either PN 1247500684 (pre MY 2001 production) or PN 2087500984 (later MY production).

You won't find a part number for the A25s1 micro-switch, unless you have access to the 'bill of materials' or 'engineering change order' for the case cover lock, because it's an internal component.

The diagram at https://www.tophydraulicsinc.com/en/...benz-a208-info shows the soft top compartment cover cylinder assembly, with the lock separated from the cylinder.


Those case case cover locks are pretty expensive.

Additionally, the DTC you found, only meant that the controller's watch dog timer, detected that soft top cover's 'closed' limit switch did not actuate, within a specified time.

Most limit switches are 'normally open', but some of them are 'normally closed'.

Enclosed is a thumbnail that explains the purpose, design and functional of the A25 soft top compartment switch group. Warning: It's valid for the early production A208 MY's.

Note that the 2 internal micro-switches toggle (e.g. when one is closed, the other is open).

When there is a problem with a switch not giving the proper signal to the controller, it's not usually a defective switch, but much more frequently, because the switch is not being actuated or a wiring issue.

In your troubleshooting, have you considered how the micro-switches are mechanically activated?

Specifically, all of the hydraulic cylinders are differential acting, which provide directional movement (e.g. moves the cylinder rod in or out), depending on whether the hydraulic pressure is applied to the rod or piston side of the cylinder (e.g. by specific valve block solenoids). Additionally, the soft top compartment cover and/or rear bow cylinders are know to commonly develop seal deterioration and leakage, after 10 years of service. Note: in additional to the port seals there are also internal seals that fail.

 

Thanks guys, very detailed info however:

This is proving somewhat harder than I anticipated as when attempting to check the voltage from the N52 connector itself I can't get any reading on any pin test.

I've tried using the vehicle ground, and pins indicated to be grounds here:

http://manual.startekinfo.com/manual...3/11_5/m22.jsp

I've even tried seeing if there voltage at the relay (pin 2 & 4) with no luck... There is 12 volts at my battery so I know my multi-meter is good...

@Plutoe, what did you use to find the p/n's?

 

fixedhalo.......I'm sure your multi-meter is fine.

Despite my previous post, for some reason, you're remained focused on the MB DTS code, which is solely based on a watch dog timer, that only suggest the that A25 s1 did not activate in a pre-described time, but more importantly, as aforementioned, while there are there numerous other possibilities. Instead of wondering where Plutoe got the part numbers, FYI they were from the MB EPC (electronic parts catalog), which possibility would be helpful to those capable of rebuilding MB modules . The PNs, I provided are for the soft top A25 cover switch group, that attaches to the corresponding hydraulic cylinder, that properly activates it, indicating closed and/or locked status to the controller. .

Unfortunately, your still attempting to read voltages at the N52 connector, which are not possible, w/o the special connector. My very educated guess is that you removed the N52 harness connector and took measurements at the N52 connector on the controller. Guess what, removing the harness from the controller, you also removed the 3 fused supply voltages that supply the controller, which would explain why you have not be able measure any voltages.

Unfortunately, while numerous power roof issues have been resolved DIY and inexpensively, given your openness to help (e.g. stubbornness and/or troubleshooting skills), I have already expended considerable effort to help, which has been disregarded, so I would have to agree with Pluto's above assessment.

 

Excellent work, Plutoe and Serndipity!

Indeed, fixedhalo's CLK55 does not have the "cover closed" switch on the case cover lock (tonneau cover lock), because that was omitted starting with model year 2001. The case cover lock p/n 2087500984 used in late production models has only the "cover locked" switch.

fixedhalo, thanks for posting all the detail. The micro switches inside the locks rarely ever fail, and I doubt very much that they are the cause of your top malfunction. What the computer cannot read, is whether the wire from the controller to the latches is okay. The wiring harness from the controller to the case cover lock can go bad, with wires breaking or shorting. You could simply unwrap the cloth tape on the wiring harness and see if there are obvious problems with the wires.

Normally, it is the wiring harness to the rear bow lock 1247700426 that goes bad in places where it flexes when the case cover opens and closes. However, a bad wiring harness to the rear bow lock would normally lead to a warning chime when the top is closed and the car is put into gear, or it would make the pump keep trying to unlock the rear bow lock when it is already open while you are pulling that soft top switch.

Out of curiosity, does the pump still move the roll over bars?

Klaus

 

Ok so first off, I do really appreciate the information you all have provided.

1. I misunderstood and didn't connect that Serndipity's initial comment re: 3 fused voltage supply meant that even if I pulled the connector there would be no power to physically check the signal from the switch to the controller.
2. I didn't go any further with checking resistance which I'll do in the morning.
3. What I didn't add but in hindsight should have in my initial post was that with the SDS connected, I could watch the limit switches, luggage cover switch, etc. open and close as I manually actuated them, but the case cover open/closed wouldn't change no matter what position I put it in. So its not a matter of the switch operating timing out, but more so that its just not responsive at all, leading me to trying to figure out if there is an issue with the Controller, the wiring, the switch, or some combination thereof.
3. @ Klaus, thank you for the information on the running change re: case cover lock as most resources I have access to point to the case cover lock having both switches. I haven't tried since the top stopped working. When I was diagnosing the top initially about a month ago, I did try the roll bar switch and got no movement.

 

This me be a valuable clue. If the roll bar did not move at all with the top either up or down, then your target for examination is the pump. You can do a simple experiment: bridge pins 30 and 87 in the pump relay socket and see if the pump runs. If it doesn't run, then you either have a bad wire at the fuse panel in the rear, or a bad pump motor blowing fuses.

Klaus

 

Bridging 30 and 87 brings the motor to life.

The resistance test in 13.1 indicates its either wiring or 1298211151.

Checking the diagram for the part and its location, I'm not sure if I know exactly where it is.



So the A25 s1 & s2 switches are item 20 in the diagram. Which in itself is helpful to know that its on the drivers side, behind the back seat bulkhead...ish, however before I go tearing apart any more of my trunk area, does anyone have an actual photo of the switch location?

 

fixedhalo,

thanks for your reply about bridging pins 30 and 87 on the relay socket. That is good news, as it eliminates the need for one of the most expensive repairs in the top system.

As for locating the switch, you are really close already. Are you sure that you have read thoroughly through all responses to your thread? Three of has have spent a lot of effort on helping you...

Hint: check how many switches there are supposed to be in your case cover lock, and check the location diagram I posted earlier.

 

Solved!

A few things of importance with relation to Serndipity's initial reply re: MY 2001 post VIN 070018 on A208's

1. The case cover locking mechanism/cylinder has only A25/s2 the soft top cover locked switch.
2. There is no A25/s1 switch. Despite the EPC drawing I posted, there is no switch in this system to indicate the soft top cover is closed. (I took apart the trunk, rear seat, and drivers side rear trim panel below the window to verify this.
3. HHTwin, the interface the SDS Tool (the one I used anyway) utilizes to communicate with the N52 controller lisn't accurate as it shows the component in the actuations menu, but it isn't apart of the system for post 070018 vins....

What were my steps.
1. I re-borrowed the SDS from a friend.
2. I manually reset the top to the retracted into the trunk compartment position.
3. I checked post # 16s documents in this thread https://mbworld.org/forums/clk-class...-failures.html for the correct state of the limit switches and locks and reset them all per the guide.
4. While having the SDS connected I attempted to actuate the top. This did not work, so I re-cycled the key and tried again. Lo and behold, the top began to move into the closed position.
5. I disconnected SDS and it closed and opened again with out an issue.

I surmise that having SDS/HHTwin interfacing with the controller was creating an issue for the normal operation of the top. By initially recycling the key, it broke the communication and allowed the top controller to function normally.

So long story short, I was chasing a fault that for all accounts was accurate based on SDS/HHTwin actuation states of the various switches, and the PRIOR switch sequences that the controller logic uses. However with the change noted, this particular switch no longer seems to exist and isn't needed in the logic of the controller.

 

fixedhalo,

congratulations, and thanks for the detailed summary. Serndipity's detailed responses are really awesome - he puts a lot of effort into being accurate, detailed, and informative. We are lucky to have him on this forum.

There is still the lingering question why the top didn't work in the first place. Did you initially have any codes that were not related to A25S1/A25S2?

Klaus

 

fixedhalo.......Glad to hear that, at this time, your power is again operational. Seems that all it took was to perform in steps 2 and 3. By the way, the informationals', within post #16, that I previously posted in that thread, were accurate for early A208s, but with caution, useful for later production models.

The difference being that beginning in MY 2001, MB made significant upgrades to the power roof components (e.g. including the controller, hydraulic pump assembly, compartment cover closed switching etc.), where not only were the succeeding components not compatible (e.g. controller logic/firmware, due to fewer pump solenoids and electrical connections, the A25/s1 switch is not longer a part of the soft top cover closed and/or locked A25 assembly etc.), using earlier tools (e.g. documentation, SDS etc.) will result in hoping to find a pot of gold, at the end of a rainbow, unfilled.

Long story short, to prevent false flags, all MB replacement parts, diagnostic troubleshooting documentation, EPC and SDS, must be specific, to a vehicle version.

In your initial post you said.........

[[[[[[So as the title suggests, My CLK55's top isn't working. I get the slow blink from the switch when trying to lower the top. The windows do go down but after that, nothing.

With the help of an SDS and a friend, I was able to determine that the car knows when the bow is locked and unlocked, when the cover is open, locked, but strangely not closed.

This is tracked down to switch group A25 s1 (closed) & s2 (locked).]]]]]]

The N52 controller has an important built in test/diagnostic capability, which not only detects malfunctioning power roof and/or roll bar functionally, but provides basic diagnosis as well as possible causes, to further troubleshoot. . Note: The detailed interpretations were also included in Post 16 at https://mbworld.org/forums/clk-class...-failures.html .

Seems to me, that the very first sentence alone, should have been your focus.

Specifically, the slow blinking lamp on your power roof switch, indicated that either your rear bow bow or compartment cover did not close and/or lock properly. Go figure!!!!

So.....now you're wondering a couple of things.

Why?......

Even after manually finding/resetting the limit switches, to a to a prescribed status (e.g. per post #16 at https://mbworld.org/forums/clk-class...-failures.html , occasionally required when replacing a switch, but faulty limit switch switches failing, electrically, have been rare .

Instead, at this point, the slow blinking, indicates that either the soft top cover or rear bow has not been properly closed and/or locked.

I know you find this confusing, at this time (e.g. because the soft top closed signal from S24/s1, does not apply in late W208s), even though your version of the the troubleshooting procedures, indicates otherwise.

I'm really pleased that Top Hydraulics (i.e. Klaus) has since joined the discussion, as he is the most knowledgeable, person regarding MB power roof repairs, on this planet.

His first question, was whether or not when attempting to open your roof, did the pump run (or not).

If not, as you since stated,, it's because the controller built in test facility told you that a slow blinking lamp, was because either the rear bow or soft top compartment cover was either not closed or locked preferably.

In further detail, the controller evaluates every prescribed input,and if OK, turns on the pump, that actuates pump solenoids. If the succeeding watch dog timer, that monitors the a solenoid time to activate,is exceeded, you'll get a DTC. body code fault.

When the pump fails to run at this point, the slow blinking lamp, indicates a fault due to either the rear bow of compartment cover not properly closing or locking.

So your next question would be, if my later model does not have a A25/s1, compartment cover closed signal, how does the controller know that cover is closed?

Easy......on A208s, there has always been another compartment cover closed switch. It's depicted as S84/5 in your documentation. BTW, you did not need to tear your car apart to find it, as it's simply attached to the compartment cover hinge (e.g. item #5 in your post #12 compared to enclosed picture of S84/5).

Additionally,rather than re-setting all the limit switches manually, which is a PITA, you can reset them all, specific to your version, by simply lowering and then raising the roof manually.

Upon further questioning by Klaus, he also asked if your pump was operational. Great question, because the outcome would suggest different courage of troubleshooting.

The power roof is fused in 3 places. The test Klaus suggested, only checks a specific and separately fused section of the power roof. It basically checks that that the fuse, wiring and most importantly, as intended, verifies that the pump motor is operational. However, it bypasses the relay's make/break contacts with a jumper. This circuit is fused by a 40 ampere fuse, draws at least 30 amperes of current to turn the pump motor on /off. When switching this amount of current, upon the make/break relay contacts, a significant spark is generated, which causes pitting of the contacts and resistance to the necessary current flow, to operate the motor. In some cases, the contacts even weld together, resulting in motor burn-out. It's a commonly available part (e.g. same as used to run the fuel pump) and as either a MB OE or OEM part, costs less than $10. While you have access to the pump...REPLACE IT!!!

Lastly, back to your initial post, where the controller cyclically checks that rear bow is closed and locked, and that soft top compartment is closed and locked (e.g. except on later models, where the cover closed switch, S84/5, is normally open and then closes to ground, when cover is closed). While it's failure has been infrequent, it's usually due to a wiring failure, at the moving hinge.


My last suggestion would be, that while you're car remains so much apart, check the level in your hydraulic reservoir. If low, the fluid did not go to heaven. You likely have one or more cylinder leaks, which have been very common, after 10 years of service. By far, the most common culprits are either the soft top cover, or rear bow cylinders. Note: These cylinders actuate the limit switches, notifying the controller to turn on the pump and they can be easily inspected, by removing the carpeted panels, inside the compartment cover..