Hello all,

I have having trouble with the convertible top on a 2002 CLK430. I have seen several posts about similar issues, I have not been able to determine a solution from reviewing them. Hoping to get some insight from the forum.

But first, I would like to extend thanks for prompt and professional service at Top Hydraulics. In addition to prompt service on parts, Klaus has been very generous with his time and knowledge in providing troubleshooting support.

Trouble began with a leaking hydraulic cylinder on the rear bow latch. Top was still working properly, just leaking fluid. I ordered a new cylinder and installed it on the existing latch.

After installing, I noticed that the hydraulic pump was whining, so I stopped operating the top until I checked the hydraulic fluid level in the pump reservoir. It was low, so I refilled with Mercedes fluid. No more whining.

Since installing the new cylinder, the top raises and lowers properly, except.......

When raising the top, the top goes through the cycle - top raises, cover closes, top lowers and latches in rear bow latch and then the cycle stops. There is no chime that signals complete, windows do not raise, and light in the switch for the top continues to flash. I get a warning chime when I drive the car - assume it is telling me that the top is not fully raised. Trunk will not open automatically - assume it is because logic is preventing it from opening.

Another point, when first lowering the top, there is a loud pop when the rear bow latch opens. May be normal, I just do not recall it previously.

I have removed the latch assembly - Top Hydraulics has checked it and it is functioning properly.

I have checked the microswitch on the bow latch - it is working properly. Klaus checked adjustment.

I noticed that the light on the headrest adjustment stays lit.

Looking for any additional thoughts. My assumption has been that the rear latch has been in a bind and is not closing completely. I had previously adjusted the prong on the rear bow that goes into the bow latch, and the latch still seemed to bind. My thought is to remove the prong completely, and then raise the convertible top. This would eliminate potential binding that occurs when the bow latch closes and allow the latch to close completely. If the top raising cycle completes (i.e. lights stop flashing and final chime is heard), this would "prove" that there is a mechanical binding issue that is preventing the bow latch from closing completely. If the top raising cycle does not complete, this would point me to look at something else. Is the limit switch on the bow latch the last switch that must be made in the electrical logic? (wiring from the switch on the bow latch limit switch to control module, or possibly next step in closing sequence if there is one, or another switch).

Seems the only reason that this troubleshooting would not work is if the prong MUST be in the bow latch before it will close. Any thoughts on this?

Or any other thoughts on the situation?

Thanks!

 

The enclosed attachments should further help with your diagnosis (e.g. specially at stage 10, what conditions all of the the limit/position switches should be providing the controller).

Forum rules prohibit me re-posting it again, but there is an electrical system diagram of the controller and all of it's inputs/outputs, in post #75 at https://mbworld.org/forums/clk-class...nt-work-3.html

 

Thank you, Serendipity. This is a very good guide. Will be this weekend before I have another chance to troubleshoot, but will see what I can find about status at end of stage 10. I/O table is very useful. Very clear on state of limit switches. Hopefully can get to a point to find out which is not being satisfied. Not real excited about removing the cover to the hydraulic unit - assume that this is best place to check status. Is there a diagnostic tool for this?
Thanks again!

 

The MB STAR DIAGNOSTIC SYSTEM (a.k.a. SDS), used by dealers and many independent shops, should be able to pin point the fault. Dealers will typically charge $100 - $150 for the SDS diagnosis.

Yes, access to most of the power roof components is a PITA, but if you have a multi-meter, using the ohms function can also check the states of the position/limit switches.

Best place to do this would be at controller's connecter. This is because, as mentioned in the link provided above (e.g. post #75), there have been wear and tear faults in the wiring bundle, that interrupted the switch conditions from reaching the controller. I believe the connector's pin out is in the suggested reading thread pointed to in post #75. If not, it's in another thread here or at benzworld.org .

While you have access, it might be a good idea to replace the pump motor relay. I bought this one, just to have on hand, but you can also find one at a local auto parts store.

http://www.autohausaz.com/search/pro...20Pump%20Relay

 

Thanks, again. I also found a control module diagram from another of your posts. Great docs. Hope to get a chance to check this weekend.