Top switches/top stuck

My 99 SLK 230 top has stuck in up position. Trunk opens, motors hum but won''t budge. Dealer DX says top switches bad$900 to replace. I know there is a access in the headliner where a hex wrench goes but I have not been able to get the top unlocked with it. Tugged and pushed but backed off for fear of breaking something. I know there must be a way to unlock the roof to allow me access to the switches which I am sure  can replace myself but can''t get to the switches without unlocking the roof  and roof won''t budge with bad switches...catch 22? Anyone have any ideas? Manual tells how to raise the roof manually but says nothing reversing the procedure. Stumped.

Did you loosen the screw on the top pump to relieve pressure first?

Hey, thanks so much for replying. I am sorry; I have no idea what you are talking about. can you humor me/help me with a bit more info? Thanks!

The hydraulic pump for the top is in the trunk on the right side. Remove the spare tire & there is a panel that can be removed from the larger side panel. You will then be able to access the pump. You will see a screw there that releases pressure from the hydraulic circuit allowing you to move the top manually.

Blueteam: thanks  for the coaching. So, after I turn the screw to release the pressure, then I should be able to turn the hex wrench to unlatch the top, right? Do I then need to retighten the screw before i try to activate the top button, or just keep cranking the wrench until the top comes all the way down? If the latter, what about the rear windows, will they come down or stay up?

If the pump is running it eliminates a number of possibilities.
Fluid loss?

1. Is the fluid level in the pump reservoir to the correct level?

2. Does the "note" of the motor change as it runs suggesting that something is preventing the hydraulic rams from moving freely?

Stuart

Stuart:  My mechanic said he checked the fluid level and is apparently Ok. There has been no spotting on the garage floor or signs of leakage either. It seems that the motor does make a slight shift in pitch but then as best I remember it seems that it always sorta ""shifted gears when it transitioned from trunk open to top retract phase. What do you think of the comment by "blueteam" that loosening the screw on the pump will release pressure on the latches thus allowing the opening and hence access to the switches, which may simply be stuck in the closed mode due to the plastic ballast holding moisture, dust, etc., as  MB enthusiast "bazzle" suggests?

Stuart: OOPS.... That was supposed to be "silicon bellows" NOT "plastic ballasts" in my reply to your posting. Looking forward to your thoughts and comments. littleb.

A few more comments.

1. You would not notice oil on the garage floor. All points of leakage would be within the vehicle itself.

2. Yep. The motor does change note as it goes thru the different functions.
So exactly what does it do since this may point to the function that has not completed corrected.

a. Windows down including rear quarter lights
b. Trunk starts to opens from rear before windows are fully down.
c. At the point where the trunk is fully open (front open) the catches for the roof to header are unlocked by means of a bowden cable.
Not sure exactly how these are actuated but if its at this point in the sequence that the roof fails to open and the cycle stops I suspect one (or both) have become detached / broken. The bowden cable (like used for bicycle brakes ) travels above the headlining, across the rear screen to steel roof hinge and down to the mechanism in the top corners of the trunk. Can be seen with trunk open normally.
I GUESS that some safety device must sense that these latches have not opened however without specific knowledge I''m out of my depth.
If the motor appears to "stall" at this point the sensing will be electronic. i.e. Motor current has exceeded a preset level since the latches are preventing the hydraulic rams from moving the roof. The load on the motor causes the current to be cut. However sensing may be mechanical or involve a switch of some sort acting as a signal. Not sure without looking things up on WIS.

Note. To check the oil level simply park the car on level ground and remove the "hatch" in the RH side of the trunck panelling just above the boot floor. You will see the oil resevoir attached to the motor and there is a simple Max / Min level mark on the translucent casing.

I didn''t see Bazzle''s post but he has a lot of SLK knowledge.

Stuart

Stuart: Fluid level is right on the money. Windows come all the way down, including rear quarter windows. Trunk opens all the way and then the operation stops except the pump continues to hum as long as I hold the button down. My mechanic/friend says he thinks the lighted button should then begin to flash to signal a malfunction but it does not. ( he can''t figure it out either). I sure appreciate you bearing with me and offering any suggestions. Oh, by the way, I noticed when I opened the panel that there was a  cable wiith an insulated loop just hanging in that compartment. It looks like an "auxilary pull" to release something (?) It travels forward out of sight and I have no idea what it is for or if it is in any way related or not to my problem. Thanks for helping me troubleshoot this, littleb.

"Loop" behind panel is emergency fuel flap opener.

I suspect but have no specific expertise on this issue that the header rail catches are not releasing.
I''m reasonably confident that the bowden cable(s) have become detached or broken but that is as far as I can go.
I''ll take a look during the course of the day to see if I can add anything further. Unfortunately I don''t have access to WIS at present.

BlueTeam has made a suggestion. Why not follow up on that?

Stuart

Stuart: FYI, the  book says that the cable(s) with loop are the auxiliary pulls to release the front hinge locks on the trunk. Thought you might want this info. There is a cable inside the panel on each side of the trunk. I just happened to come across this bit of trivia.
littleb

I stand corrected.

So I now know where the "bowden cables" terminate!

Stuart.