CapitalB666

Hi

New to the forum and Mercedes.
I am the proud owner of a 2002 CLK430 a true barn find. The car had been sat for 2.5 years in a barn with the top down so a lot of cleaning has been required.
I now have it running perfectly with everything working with one exception.......The dreaded roof.
I have read all the posts i can find and done all the tests i have managed to read up on BUT....
The Roof opens perfectly to the book and everything does as it should but on closing everything works up until the bow locks, at which point i believe i should get the same chime i get when i open the roof. Unfortunately i don't ...Although this is not a major problem it is annoying as the boot can not be opened without using the key.
From what i have read and i hope i am reading correctly this would point to a problem with the bow lock or switch but both seem to work fine i have metered the switch at the switch at the connector and at the ecu and it seems to do what it is supposed to do....

I have checked all rams and switches and all seem to be doing what they should.

What am i missing ???? Any help would be appreciated.

Rob

Mercnotworking

OK, The good news is that it doesn't seem to be hydraulic or electrical as your hood opens well. It seems like one of your switches isn't working. I had a very similar challenge to overcome and after 18 months I got it sorted. Hopefully you won't take this long to fix this.

See https://mbworld.org/forums/clk-class...p-problem.html

Serndipity's diagrams are invaluable for trouble shooting.

Continue enjoying your CLK, Good Luck and have fun.

David

CapitalB666

Thanks Mercnotworking

I won't give up i will keep testing and trying....

Serndipity

Hi Rob,

Great to see that you did a forum search, found lots of documentation regarding how the the power roof operates, but still find yourself stumped at this time.

That's because during MY 2001, MB did much more than a typical cosmetic refresh.

The positives are that your throttle-body was upgraded to the same as used on the AMG 55 models, the ECU was upgraded from Bosh Motronic 2.0 to 2.8, the turn signals are now LED lamps on the outside mirrors etc..

However, there were also significant changes to how the power roof functions on later model A208s.

Specifically; the hydraulic pump motor being better protected from repeated attempts of operation (e.g. vs. just the prior watch dog timer), but more importantly other changes, such as the pump assembly now having a valve block of 5 solenoids (e.g. formally 7), the A25 switch group now only using a single circuit (e.g. formally 2 circuits to indicate both closed and locked).

That said, the following diagram included above, hows it's inputs (left side), outputs (right side) and requisite CANBus conditions.

Specifically the soft-top operation control module (N52) cyclically supplies the information "SOFT TOP CLOSED", "SOFT TOP UNLOCKED" or "SOFT TOP OPEN" to the CAN databus.

As soon as the message "SOFT TOP UNLOCKED" is received, the pneumatic system equipment (PSE), combi-functions (A37) no longer performs any remote trunk release operations.

At the same time,when the trunk lid is open (unlocked), the soft top cannot be operated because the possibility of a collision between the trunk lid and the lid of the soft-top compartment. Additionally, even though the roof is closed and locked, if the A37 controller trunk controller thinks the trunk is unlocked, the trunk will not open (except with the mechanical key).

Although using the MB WIS schematic electrical diagrams, I may be able to update the stages of roof operation to suggest next steps, have you noticed other malfunctions indicated by the N52 controller's built in diagnostics ?

CapitalB666

Hi Serndipity.

I Realized part way through testing something was odd as one of the switches goes to pin 47 i believe and there was no pin at 47 on my unit may be a different number but all the same i picked up something was odd. I then went through all of your posts on this subject and found the correct info.

I then retested everything and still no luck all signals seem to be correct, As you point out above no trunk operation when it thinks roof is open or moving this function is fine and if trunk is open no top movement also working correctly.

With roof fully open trunk opens via dash button or key fob with roof fully closed trunk can only be opened with key.. When i open the roof everything is correct i get the "I'm done chime" windows and roll bar go up all good. When i close the roof it all goes good until the step where i should get the "I'm done chime".

This led me to believe it sort of had to be the bow lock switch as its pretty much the only difference. ??

Please enlighten me on the built in n52 diagnostics this is something i have obviously missed and i apologize accordingly.

Thanks for helping.

Rob

Serndipity

At the end of each soft-top opening or closing operation, a chime signal is sounded for 1 s from the overhead control panel control module (N70), which confirms the correct implementation. On closing the roof, the chime will sound as soon the power roof operation ends (e.g. does not require the manually locking of the front bow).

Also, with an incorrectly locked soft top, in driving mode, the chime will provide a 10 second warning signal. Note: further output of the warning signal, will reset (e.g. Ignition "ON" and "OFF" again or a change in the state of a limit switch).

I'm curious regarding the status of the lamp in the trunk's remote release switch located on the center console. Specifically when ever the truck is unlocked, whether using the console release switch, fob or mechanical key. the lamp will illuminate until the trunk is closed and locked. When you close your roof, is the center console trunk release lamp lit?



As noted in the hashed box, as of May 2001, the A25 switch was updated.

The A25 switch in earlier A208 models included a pair of switches, that told the N52 controller if the soft top cover was closed or open as well as when the soft top cover was locked or unlocked. The part number was 1247500684, which was formally used in the 1990's W124 E class cabriolets.

The updated A25 switch in later A208 models only has one switch and is part number 2087500984.

The reason may have been that there was already another position/limit switch, as shown below, that indicated the open/closed status of the soft top compartment cover.




Whenever you turn the key to position 2, or start the vehicle, the lamp in the power roof operating switch will illuminate briefly, while the N52 controller checks the power roof status.

CapitalB666

Hi
Just popped out and checked i have continuous illumination of switch when stationary and 1hz flashing once moving which if I am reading correctly means "Soft Top Not Properly Locked"

I will go through all the switches again tomorrow if i get time, I left my iPhone in the trunk videoing today to prove to myself the bow lock was doing what it should and it all appears fine Locks and unlocks without fault.

Im not going to give up but it is frustrating lol.......

Serndipity

Hi Rob,

I believe we're making some progress.

The additional information you supplied; regarding the diagnostic status / information being supplied from your main soft top operating switch, as well as having full remote operation of the trunk, after the roof is opened and verified by the short chime, but only having to use the mechanical key, after closing the roof and not hearing the verification chime, was very helpful.

Specifically as mentioned in post #4, the soft-top control module cyclically supplies the information "SOFT TOP CLOSED", "SOFT TOP UNLOCKED" or "SOFT TOP OPEN" to the CAN databus and as soon as the message "SOFT TOP UNLOCKED" is received, the pneumatic system equipment (PSE) module (A37) no longer performs any remote trunk release operations (e.g. using the center console trunk release switch or fob) . This is done to eliminate the possibility of a collision between the trunk lid and the lid of the soft-top compartment. However, when this occurs, you will only be able to unlock and open the trunk using the mechanical key.

At this time, it appears that you have an issue when closing the power roof and not with the central locking system.

Assuming that you have the previously posted information, from other threads, that shows the stages of roof operation (e.g. when either opening or closing the power roof), that are required actualization's of the corresponding position limit switches (e.g. occurring at a specific stage of operation). Not only does this provide additional diagnostic information (e.g. pointing to a basic point of failure), but also will greatly assist in the troubleshooting and repair.

Because you're frustrated, but not willing to give up and almost always the power roof can be repaired inexpensively, my suggestion would be as follows.

With your roof is open, verify the status of the position/limit switches, as shown below. I know after opening the roof you got the short chime, but this will eliminate that an anomaly did not occur that affects the lack of chime when closing the roof.

Then close the roof and verify the status of the position/limit switches.

Here are the resistance reading, taken at the disconnected N52 controller connector, that verify the switch status vs. stage of operation ( e.g. that should reflect the power roof's upgraded system components, made during MY 2001).

A25/s2 Soft top cover locked/unlocked




S84/5 Soft top cover open/closed



S84/16 Rear Bow locked/unlocked



S84/15 Rear bow opened/closed





Also check the S83/5 Roll bar retracted

CapitalB666

Hi Serndipity.

Thank you for your patience with me I have all the info printed out from previous posts and i have tested every switch at N52 numerous times BUT this weekend with the additional info you have supplied i will go at it again.

I will not give up it will not beat me lol, but it does seem like 40 year as a field service tech on all sorts of electro mechanical equipment is wasted when it comes to a Mercedes convertible top......

Thanks again for your help and patience I will get back to you with the results.

Rob

CapitalB666

Another day of getting nowhere lol, I noticed you asked for the status of the trunk / boot release light, it only illuminates when the trunk is activated or open it does NOT illuminate during operation of the roof.

The result for the above tests are as follows.

Roof fully open
Pin No 10 2.2 ohms
Pin No 50 infinity
Pin No 29 infinity
Pin No 11 2.2 ohms
Pin No 16 2.1 ohms

Roof fully closed
Pin No 10 2.2 ohms
Pin No 50 infinity
Pin No 29 2.2 ohms
Pin No 11 2.3 ohms
Pin No 16 2.1 ohms

Roof in a halfway stage bow and cover vertical
Pin No 10 infinity
Pin No 50 2.3 ohms
Pin No 29 infinity
Pin No 11 infinity
Pin No 16 2.2 ohms

I hope this tells you something its not telling me.

Thanks again for all your help.

Rob

Serndipity

Hi Rob,

Great job......I believe your thoroughness in making and reporting the suggested position/limit switch measurements, this time, found the problem.

Specifically, when you open your roof, the your rear bow is not locking.

This is indicated by the ohm reading, for the S84/16 rear bow locked switch, being infinity ( e.g. greater than 20K ohms), at pin 29 at the N52 harness connector, (e.g. it should be 0 - 5 ohms when locked).

Also, as aforementioned:

-Whenever the power roof is being opened or closed and/or if the procedure is not fully completed (including being locked), neither the key fob or the center console release switch, will open the trunk.
-Additionally, the diagnostic provided by the 1 Hz flashing lamp, in your power roof's operating switch, was also indicating that the soft top or the soft top compartment cover was not properly locked .

Typically, when this occurs, the power roof will not operate, which begs the question, of why were you able to open and close your roof (except having to use the mechanical key to open the trunk, whenever your roof was open)?

That's because when you went to close your roof, the controller evaluated and found that your rear bow was unlocked and proceeded to normally close the roof.

I'm glad that you also reported the switch measurements, both with the roof fully open and closed, because the upon closing the roof, the rear bow locked, as it should.

At this time, my troubleshooting/repair suggestion would focus on the rear bow lock cylinder.

The seals that MB used, have a service life of +/ - 15 years (less in vehicles operated in warm climates) and the cylinders that frequently fail are for the compartment cover and/or rear bow locks.

Also the cylinders are differential (e.g. the shaft moves in 2 directions and the direction of motion depends on if the hydraulic pressure is applied to the piston or rod side. See below for more information.


Even if the the cylinder's port seals are not leaking, the condition of the internal seals, that provide the direction of motion, may have deteriorated, which would explain why the bow locks at the end of closing the roof, but not when opening the roof.

Top Hydraulics has put together a .

Hint: In the 'practical hints section' section of the owner's manual, there are detailed instructions on how to raise the roof manually. Step 15, shows you can unlock (or conversely lock) the rear bow, using the hex allen key supplied in the vehicle tool kit. With your top open, you can then manually lock the bow, by turning it in the right direction, then close the trunk and then see if the fob or console switch will operate the trunk. If you try this, make sure your mechanical key is not inside the trunk, when you close it.

CapitalB666

Now this is why i get confused by the problem because trunk opens when roof is open but not when roof is shut lol
I will work more on the bow switch and piston and get back to you .

Thanks Again

CapitalB666

Hi Serndipity

I have not given up i am still fighting with my roof i have re gone through all switches etc over the last few weeks still no headway.

Roof down trunk works Roof up no trunk opening

it does not matter what i do i even locked myself in trunk while SWMBO moved roof up and down still no joy i just can't find what's doing it.

Could the control box be the problem ??

Rob

Mercnotworking

If SWMBO locked me in the boot, she might not let me out.

CapitalB666

i have to admit i was scared she would leave me there LOL

Serndipity

Hi Rob,

Why the heck did you lock yourself in the truck?

For diagnosis, troubleshooting and repairing of the power roof, it not a required or recommended method.

BTW, while you were locked in the trunk, you probably noticed a green light on the driver's side of the trunk lid. However, should you ever find yourself in that situation again, push it because it's actually an emergency trunk unlock switch.

I believe I know why your power roof operates normally, to open and close roof, but when the roof is open, you center console truck release switch or your fob will not open the trunk.

Recall, that the control module (N52) cyclically communicates with the pneumatic system equipment (PSE) combination pump-controller (A37), via the CANBus, with a digital message that that indicates, SOFT TOP CLOSED, SOFT TOP UNLOCKED or SOFT TOP OPEN.

By design, to eliminate the possibility of a collision between the trunk lid and the the soft-top compartment cover, whenever one of these messages is amiss, either the soft top cannot be operated or central locking will no longer perform any remote trunk release operations.

As you know, the power roof operating switch can be released during roof operation and then pressed again, to resume operation, in either direction.

Your power roof operates normally, because the controller sees your roof as being closed, as well as the rear bow has locked OK (e.g. which is only relevant upon closing the roof), but does not yet know that your roof has completed opening (e.g. missing the SOFT TOP OPEN message).

The state of the roof being closed or open is provided by the S84/13 switch group position/limit switch.

As shown in the diagram below, it consists of 2 separate switches (both with normally open contacts) where :

- When the roof is closed the contact in S84/13s1 will close (e.g. switched to ground).
- When the roof is open the contact in S84/13s2 will close (e.g. switched to ground).



With the roof completely open, measure pin 33 to ground, which should be between 0 - 5 ohms. If not, you have finally solved the puzzle.

Note: Neither of the switch contacts will be closed when the soft top is in an intermediate position (over a certain range).

CapitalB666

Hi Serndipity

So my problem is not when roof is open it is when roof is closed !!

Laying in the trunk was so i could test the signals as they happened rather than in a test environment just to see if i was getting different results LOL I did find the big green button but fortunately swmbo did let me out.

Pins 31 and 33 are showing correct figures at the right times i honestly can not find any wrong signals at N52 but i will go through it all again today.

Thanks for your Patience

Rob

Serndipity

As explained in post #16, in order for the central locking system to open your truck when the top is open, the 'soft top open' CanBus digital message needs to be communicated (e.g. between the N52 controller and the A37 PSE controller). Therefore as the top lowers, the contacts between the 2 separate switches in the S84/13 switch group should properly trigger and provide the status that the roof is fully open, which is a necessary condition for the central locking system to open the trunk, which is what I thought might have been the culprit.

As mentioned in post #6, at the end of each soft-top opening or closing operation, a chime is sounded for 1 s from the overhead control panel control module (N70), which confirms the correct implementation.

When you operate the power roof, do you hear the chime when both closing and opening the roof?

When you turn the key to position 2 or start the car, the power roof operating switch will light up briefly, while the controller does a self test, checking the status and function of the power top operation. and then turn off.

As described in another document in post #6, if the self test detected a fault, the indicator lamp will remain lit when not being pressed and/or flash.

At this time, does your roof's console operating switch indicate any malfunction?

When the roof has been opened, there is another position/limit switch actuation that the N52 controller expects to see is. Specifically the S84/15 position/limit switch tells the controller if the rear bow has is up or down.

Here's how to verify that the S84/15 rear bow up/down switch is working properly.

CapitalB666

Hi Serndipity

I am sorry if i am frustrating you

When i open the roof windows go down roof opens and i get the chime if i activate switch again roll bar and windows go up. no light on switch and no alarm when i drive. Trunk opens with remote and switch in car.

When i put roof up windows and roll bar go down roof comes up and cover and bow shut and lock but no chime. light on on switch alarm dings if i drive trunk does not open via remote or switch.

All signals are correct as per #16 and #8.

I will have another go tomorrow.

Would you know if part number A 208 820 30 26 is the correct ECU just to put my mind at rest lol.

I really appreciate your help

Rob

Serndipity

Let me know if you have questions regarding the above.

CapitalB666

Hi Serdipity

Please refer to posts #1, 5, 12 and 17 i clearly say problem is with roof closed.

I have today rechecked every function of switches and rams and all are working without exception. At all stages the outputs are correct.

I am begining to think that the ECU has failed, Thanks for the tip on using EPC it has confirmed it is the correct unit.

i will get back to you once i have tried a replacement ECU

Thanks for all your help.... Rob

CapitalB666

I got a replacement ECU on eBay for $100 fitted it and all is good now

thanks for all the help

Serndipity

Hi Rob.....Fantastic!!!!

The $100 was a very good price and more importantly, the last I looked, the folks selling roof controllers on eBay all indicated that it would work for any 1998 - 2003 CLKs, which is incorrect.

After verifying that all of your position/limit switches were actuating correctly, your power roof was opening/closing OK, except for the chime not being present to verify correct implementation when the roof closed, as well as the central locking system being able to open your trunk when the roof was open, had to do with the controller roof's control module (N52) not properly communicating with the pneumatic system equipment (PSE) combination pump-controller (A37), via the CANBus.

It would have only been possible to further diagnose and troubleshoot the controller, by checking the supply and signal voltages on the controller's outputs and CANBus with voltage measurements.

However, this would require access to the harness wiring when it was connected to the controller, which requires that a breakout box be inserted between the harness and connector. The breakout box is available as a MB part, but it cost nearly $3,000.

Then you could have checked that the CANBus high line was 1.8 volts and oscillating, the low line was 3.2 volts and oscillating and that the voltage upon the end roof operation between CAN low and high was 1.4 volts and that after approximately 30 seconds, increased to 4.8 volts (sleep mode).

Dollars to doughnuts, that is what was not working properly in you controller.

While you still have access to the hydraulic pump, I would strongly suggest that you replace the relay the powers the pump motor, as it has been a common point of power roof failures and if required top-off the hydraulic fluid.

It fails not so much because of high inrush current upon motor startup, which can potentially weld the contacts together (upon which the motor will run continuously until you pull the 40 ampere fuse in the truck or the motor burns out). The primary problem is that it's switching a highly inductive load (from the motor winding) and when the motor is switched off, the stored back emf causes a high voltage arc across the open contacts, which in time damages the contact surfaces, where the resultant resistance will no longer supply the necessary current to operate the motor.

It's not an expensive part. I ordered the Hella OEM part, just to have on hand as a spare if ever needed. It's also the same multipurpose relay used in other vehicle systems (e.g. the fuel pump).

Here are the AutohausAZ links for the Febi fluid and relay.


https://www.autohausaz.com/catalog/c...uid?s=d&page=1

https://www.autohausaz.com/catalog/c...lay?s=d&page=1

CapitalB666

HI

Thanks to your information i checked the listings until i found one with the exact same part number which i had confirmed on MB EPC as you advised.

It was listed for $169 or make offer i offered $100 and he accepted it

All good now

Thanks again for all your help.....