This is the diagnosis. The dealer said they cant replace that, they have to replace the entire roll bar for $7K...

 

Following is a copy and paste, from post #29, in your prior thread https://mbworld.org/forums/clk-class...-go-bad-2.html


-------------Start of Enclosed Text-------------

When the indicator lamp in the power soft top switch (S84) is permanently illuminated with the vehicle stationary and S84 is not operated the causes may be:

The soft top controller (N52)
Soft top or soft top compartment cover is not locked properly
Wiring or fuse, terminal 30
Defective or wiring open-circuit at the power soft top switch (S84)
The RB "retracted" switch (S83/5) or RB "extended" switch (S83/6)

Before the controller will unlock the rear bow at stage 3, it first checks that the position of the RB limit switches are correct (indicating that the RB has been lowered).

It's possible that one or both failed to actuate correctly when you operated the system under low hydraulic system pressure.

You may be able to reset the RB limit switches as follows. With the RB switch (S83), on the dashboard, fully extend the RB and hold it for 5 seconds, followed by retracting the RB and hold for 5 seconds.

You can also try the subsequent locking procedure described in the thumbnail.

-------------End of Enclosed Text--------------


If the either of the resets that I suggested prior, do not reset the limits, one of your RB limit switches is probably faulty, but the dealer most likely did not tell you which one. That's because MB does not sell the RB limit switches for the W208 and repair is only by replacement of the entire RB assembly is required for $$$$$.

However, you can determine which switch is faulty, by raising/lowering your RB into the up / down positions and checking for the required resistances, with a multi-meter set to read ohms. Note: After moving the RB into each position, disconnect the N52 controller connector and read the resistance between the appropriate RB limit switch pin, on the connector and ground.

Here's some good news. MB does sell the required limit switches inexpensively, as a R129 part.

However, access to and replacement a RB component, requires the removal of the rear seat (a PITA). See enclosed picture for switch locations.

After determining which switch requires replacement, to obtain the needed part number, search the W208 forum further or call/email Klaus at Top Hydraulics who may be able to provide you with the R129 part number.

 

Thanks! I'll get in this over the weekend. The tech said he hasn't done one, but did say access through the back seats and maybe the quarter panels. He said the switch was not reading any change downward, it was on the up side.

 

There have been several prior instances of RB limit switch failures and DIY replacements within the W208 forum. As I recall, only the rear seats have to be removed for access to the RB assembly.

First try resetting the RB limit switches, using main the dash RB switch and then the subsequent locking procedure, as I suggested in prior posts (see last comments at end of this note).

Also you can verify that the S83/5 operation is "not reading any change downward" as follows.

1. Move the RB to it's down position.

2. With the ignition OFF, disconnect the N52 controller cable.

3. Connect a multi-meter, set to read ohms at it's lowest ohms range, between a vehicle ground and pin 16, on the RB "retracted" switch (S83/5)) on the cable connector.

4. When the S83/5 RB limit switch RB switch has been properly actuated, indicating the the RB is completely retracted, the meter should read 0 ohms (no more than 5 ohms).

I've enclosed diagrams of the N52 connector pin assignments as well as how to connect the multi-meter, to the disconnected N52 cable.

BTW, there's a chance that the switch is not faulty, but is only not being properly actuated by the RB mechanism. This may be a result of operating the power roof with low system pressure (as mentioned in your other thread), or has mechanically become loose due to long term vibration, which in either case, is only out of adjustment/alignment).

 

Thanks so much for all of the help!

 

Here is the faulty switch...