98sl500

I have a minor problem with my top on a '98 sl500.

In the process of replacing the windshield header, one of the wires broke off of the Magnetic Proximity Sensor PN 129 821 14 51 that's mounted just over the rear view mirror. My top functions properly with the exception that it doesn't lock closed hydraulically.

I've ordered the new part but, in the meantime, is there a way to "fool" the Proximity Sensor so that I can hydraulically close & lock the top?

Top Hydraulics

98sl500,

The magnetic sensor A129 800 14 51 reacts to a magnet in the front of the soft top. It is used in model years '94-'02. The sensor is located in the windshield header panel, which normally gets removed only for inspection or replacement of the front top lock cylinders A129 800 16 72. When removing the windshield header panel, it is important to disconnect the sensor from the wiring harness before lifting off the panel completely, or a wire could break off the tiny glass tube in the sensor, as has happened to you. This is described on page 3 of Top Hydraulics' DIY cylinder removal instructions http://www.tophydraulicsinc.com/R129...%20Removal.pdf.

Normally, when a wire is broken on the sensor, the top will not UNlock. Is the wiring okay on the front locks A129 800 07 74 and A129 800 08 74? The firmware in the soft top controllers has been changed over the years, and the soft top controller may also react differently when it has already accumulated some other error codes, which could explain the unusual symptoms.

I assume that shorting out the sensor's connector will produce more error codes, because the controller will find it illogical to get a soft top proximity signal from the front when the top is actually retracted. Thus, you are probably best off manually latching the front until the replacement sensor is installed.

Please let us know if only replacing the sensor resolved your problem.

Klaus

www.tophydraulicsinc.com



R129 SL-Class convertible top hydraulic cylinder and pump location diagram

98sl500

Klaus:

I haven't tried to "manually lock" the front of the roof yet. Before I try just a couple of questions:

1. Must the windshield header panel be in place?
2. If "1" is YES, does the old sensor have to be installed in the header?
3. Assuming I can manually lock the front of the roof, will the rear window automatically lock after the front has been manually locked?

Thank you,

bob

98sl500

KLAUS:

Replaced the Magnetic Proximity Sensor today but now have a new problem. Which, I think, is a synchronization problem.

The top will go down and store successfully. All locks are engaged, rollbar automatically raises, and Windows work fine.

When I attempt to close the top, the rear storage lid opens, the Windows and rollbar go down, the top raises fine and the front locks lock. However, when the rear storage lid attempts to close, it closes part way and stops, then closes a little further and stops, then finally closes and locks. The rear window then attempts to close but "toggles" back and forth and never does close. The only way to lock the rear pins is doing it manually from the trunk. I did notice that the rear locks were closed so I had to first open them manually, hold the rear locking pins down and engage the locks.

To try and solve my problem I've removed the negative battery and resync the Windows. I also noticed that the soft top light now stays on. Windows work fine (go up and down, partially open when the door opens and close tight when the door is closed). The rollbar also goes up and down fine.

I have not had a chance to drive the car yet to see if the controller resync's itself. I also have not tried to disconnect the negative battery cable overnight.

Any suggestions will be greatly appreciated.

Bob

98sl500

Klaus:

This is an update to the problem after I changed the MPS.

Top was closed, windows up, rollbar down, and rear locks had been manually locked. With the key in POS 2, soft top light stayed illuminated.

Removed the negative cable and put jumper between positive of battery and negative cable. Left the cable off, with jumper, for 18 hours.

Reconnected negative cable (w/o jumper wire). With key in POS 2, soft top light was illuminated. I resynced the windows. Verified they dropped about 1/2" when door opened, closed tight when door was closed. Lowered the soft top. Everything worked fine, i.e., front locks unlocked, rear cover raised, roof dropped into storage area, rear cover closed and windows closed. At this point, the soft top light was out (not illuminated).

I then tried to raise the top. Windows went down, rear cover opened, top came up and front locks locked, rear cover closed fine. However, rear half of roof (rear window) again oscillated back and forth but would never drop. Turned the key to POS 0. When putting key back to POS 2, soft top light was illuminated. Rear locks, again, had to be manually operated.

I sorta at my witts end. Prior to changing the Magnetic Proximity Sensor, the top functioned perfectly.

As before, any help will be greatly appreciated.

thanks

bob

Top Hydraulics

Bob,

Almost certainly, the problem lies in the micro switch(es) on one or both front lock cylinders needing adjustment. This happens if folks replaced their front lock cylinders 1298001672 and accidentally bumped the lever on the front lock that triggers the micro switch.

Here is how to check whether it is one of those micro switches needing adjustment, and which one:

After the top has locked in the front, put the soft top tool (6-mm Allen wrench) into the front lock on one side, through the hole in front of the visor. Turn the wrench such that it locks even farther, taking the play out of the lock. That direction is different on the opposite sides, by the way. Holding the wrench in the far locking position, push the soft top button forward and check whether the top now fully closes in the rear with the windows going up afterwards.

Try the same on the other side.

If you find that holding the wrench on one side does the trick, then that switch needs adjustment. I will explain the procedure below and include some pics that should illustrate what I'm talking about. Once you know how to do it, it's quite simple!

(You might get away with only adjusting the prongs on your soft top, following the instructions in http://www.benzworld.org/forums/r129...djustment.html, but that would likely be only a temporary fix and eventually result in the chime going off every time you drive over a bump.)

Note that you need to re-install the windshield header panel before the top will operate on model years '95+.

The micro switch on the front lock(s) gets pushed DOWN by a lever when the lock is OPEN. There is some reverse logic involved here, so take it slow and read very carefully.

As the lock receives the soft top in it and locks, the small lever that is pushing on the switch releases just enough for the switch to click open once the lock itself is in closed position. If the lever has been bumped or bent when the front locks were installed, or if the locks have developed play over the years, then oftentimes the lever is not pushing down far enough by the time the lock is in the final (resting) locked position. This resting position can be different from the locked position without the top being latched down by the lock.

In your case, you probably have to bend that lever up just a tiny bit (1 mm or 1/32 inch). This adjustment can be made without removing the lock. Remove the windshield header panel and adjust the lever above the micro switch until it barely touches the switch when the lock is closed. Note the play in the lock - you need to recreate the position the lock would be in if the soft top was closed and pulling up on the lock. This is shown in the third photo with the caption "Front lock in real life with the top pulling". Ideally, the boot of the switch will just start bulging when the lock is in the "real life closed position".



Left front lock A129 800 07 74 or right front lock A129 800 08 74 in open position, with lever pushing down on micro switch.





Front lock manually closed all the way, keeping tension on the Allen wrench.




Front lock closed with top pulling up on it and the lever in ideal position


Klaus

www.tophydraulicsinc.com

98sl500

Klaus:

You were correct about the front lock micro switch.

I unlocked the top manually and removed the windshield header. In the process of doing this, I noticed that the passenger side lock guide (black plastic on the header) was loose and out of alignment. Once I checked everything I very carefully put it all back together and VIOLA the top works as it did before. Windows, rollbar, and top all function normally.

I want to thank you for your help. I read a good number of the threads that you provided information for and, over the last two days, learned more about the sl500 top mechanism than I care to admit. It was a great experience.

Thanks again,

bob