Been having problems with my 99 SLK hardtop. Been to dealer twice, with a total of 9 hours spent by technician trying to figure out cause of hardtop failures and these failure codes, but to no avail. Dealer finally recommended replacing hydaulic unit and 2 hydraulic pistons, but could not even guarantee that this repair would solve problem. This left me very unsatisfied with my service experience at a luxury marquee dealer. Even though my car is 5 years old, it only has 31.5k miles on it, so am very disappointed that the hardtop is already malfunctioning. Going to a second dealer to get a second opinion. Living in northern cali, it sucks driving with the top up with the sunny, but cold, weather we've been having!

My personal guess is something is jamming the linkages causing motors to overload that leads to fuse for hydraulic unit to blow. Told this to service rep at dealer, but think it went in one ear and out the other. I don't plan on being a repeat customer there, that's for sure.

Just venting....

Can you describe what the top is or isn't doing? You say they have fault codes, that should help them somewhat........

By looking at your post, it looks like the dealer is really "in to" throwing parts at a problem. There are pressure gauges they can use to find out if the pump pressure is OK. If the pump pressure is good, and there is a hydraulic problem, and there is no binding or anything, then a hydraulic actuator makes sense (and it may be hard to determine which one it is, left or right). However, just recommending a pump AND actuators at the same time? Nah, no way.

Maybe another dealer is the key, or asking if they can have a shop foreman in the shop you go to now have a look at it, sounds like even after NINE HOURS of "training" (at YOUR expense, BTW) the guy who is looking at it now hasn't a CLUE.
I'd be PO'd, I'd talk to the service manager about the situation for sure.

Hope you have seat heaters for the cold weather driving, it can be a rather exhilerating (sp?) ride, kinda fun if it's a sunny day.
But that's not the POINT is it!?

Gilly

PS My experience has been that usually these tops have problems with the micro-switches and sensors used to operate the system (detect where the top is and what operations have been completed) rather than pumps and actuators and all the stuff that actually DOES the work.

Thanks for your input and prompt response Gilly. I really appreciate it.

Regarding what the top is or isn't doing, here's what happens. While in the process of bringing the top down or up, the process would just stop. The light on the switch would still light up, but there's no more further mechanical operation, except for the quarter windows. Those small windows still would go up and down (thankfully as it has rained here). I would then have to manually close the top by following the instructions in the owner's manual by bleeding the pump, and manually securing the roof and the trunk lid. The quarter windows, however, would still go up and down, but everything else related to the hardtop operation would not work (i.e. the trunk lid opening and the roof coming down).

Also thought I'd write you the technician comments from both my vists just to get your take and any further suggestions you may have. Hope you don't mind.

1st visit - "Manually loosened bleeder screw and secured the roof to the trunk. Roof wil not open and trunk lid is not flush to rt quarter panel. 40 fuse blown and hydraulic unit relay bad. Fluid low and both RAMS for retractable top seeping. Function test top it was inop, install sds and check for codes severa over limit codes cleared codes and activate top only window operate, found fuse 25 blown, installed breaker still inop tested all switches they were ok. Found relay for hydraulic unit bad need to replace fuse and relay before diagnosis, may need hydraulic. Unit low on fluid and both top rams seeping. Tested top several times it worked ok but temp for hydraulic top pump code came up low fliud low? Replaced relay and fuse topped off fluid, temp code no longer comes on, and fuse not blowing. Will need to have leaks fixed and hydraulic unit replaced if acts up again."

2nd visit - "Replaced fuse 40 and hydrolic unit relay. Recommended may need to replace hydrolic and repair leaks if problem persists. Recommend hardtop pump assy and both rams. Function CK retractable top, verified inop, ck for codes, found B1263 hydraulic unit temp above 95 deg C. B1266 Hydraulic unit jammed. B1272 limit switch signal S69/1, s69/2, s69/3, cleared codes, ck roof operation. found trunk switch out of adjustment, adjusted switch, ran hardtop pump, ck pump temp temp was at 110 deg. set code and stop ped working, ck pump fliud level, it was low, topped off pump, rechcked pump still setting codes for pump temp and jammed, cleared and lubed top hinges, still setting codes, hardtop cylinder rams starting to leak."

After re-reading all this, I guess the technician did 9 hours worth of work, but it may have ended up not doing much. Does all this justify a $2.5k repair, in your opinion?

Hi Gilly! I am his Dad and a mechanical engineer but I can not really understand what the service technician was saying. I agree with you, seems unlikely that pump and piston pumps would all breakdown for $2,500 + (after they already billed $1,000 for 9 hours of labor, 3 sets of fuse and a relay) I was certain that they did not know what their doing and using my son to finance their experimentation. They never measured or said anything about the hydraulic pressure measurement which make more sense than the temperature. They keep saying a leakage but then, there is no sign of leakage whatsover. I bought a C class from this dealership and I intend to buy another car next year and certainly will avoid them but youur suggestion would be appreciated.

Thanks again!

I've never run into one acting "just like" this one.
I do have some training materials here and if I get time I can study them a bit.
The top operates in a series of steps. It can't go on to the next step without verification by various micro-switches and sensors that the previous operation has been completed. Simple enough so far, right?
So for example we know that the windows need to go down, including the 1/4 windows, and it is doing that. We know (I believe) that the top unlatches above the windshield and begins to come back, and that the trunk lid is opening (pivoting rearwards). These operations all have switches and sensors to indicate to the control module that "Yes, this is done, proceed with next operation, we're good to go". It seems like what you are saying is it gets about as far as I've described and then just stops. There is this computer the tech uses, what they refer to as "sds" (star diagnosis system) that can monitor all these switches and tell if the control module is getting "the green light" to proceed from all the sensors and switches.
The one I personally would scrutinize the most is the one that tells the control module that the trunk is all the way back. No way in hell the control module will try setting the roof into the trunk if it isn't sure that the trunk lid is out of the way. CRUNCH!!!
What may be happening is the pump may continue to run (in case the trunk lid is just moving slower than it should) while in fact it IS all the way back (poor switch, not sending a signal) and is overheating the hydraulic fluid and possibly even causing the rams to seep. This whole thing with topping up the fluid, boy I sure hope the rams aren't junk now. My first recommendation for the time being is to NOT hold the switch and run the pump, this isn't proving anything. Just making things worse.
They've gotta go back to square one on this thing I guess. Get SDS hooked up, look at the signals they are getting and find out IF they are getting the proper signals and if it's not working right, sure, then maybe suspect the hydraulic unit or control module. I think the whole reason that the control module thinks it has a jammed hydraulic ram is that the switch telling the control unit the decklid is back all the way is bad or misadjusted. The only way the control module knows that a part of the top is where it should be is by the switches, it's not THAT SMART of a unit that it just "knows". They need to clear codes, then watch the switches and look at where everything is when the top stops working, they should be able to figure out RIGHT THERE where the problem is. Unless at that point there is fluid gushing out of a ram, but I bet it's not.

Gonna try another dealer, or print this out and show it to them, or what?

Gilly

Thanks so much for your response. Will definitely be printing this out and showing to another dealer. Hope you don't mind. I've tried to contact the service manager at the initial dealer several times now, but have not received a call back yet. I'm done with that place.