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Discussion Starter #1 (Edited by Moderator)
Soft top problem

Hi, can someone help me.
I have a 1992 sl500, I just finished replacing all the seals in the hydraulic cylinders. Sent them to Dennis Ficken, he did a fantastic job. My problem is that I can't get the top to automatically go down, I push the button, the pumps starts but the locks don't unlatch, and then the pump stops. If I put it down manually it will come up automatically and latch properly. I have tried ever thing I can think of. Please help me.
 

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In my experience the only way to reset an early soft top controller is to remove the electrical connectors at the module. I only ever did this once; it was long ago, and I don't remember the circumstances. I later read a post a MercedesShop - Mercedes Benz Parts and Technical Information by a tech named "Gilly" who had the same experience. Anyhow, if one were to perform such a reset, I will guess that it would be best to have the top in a "home" position, and by that I mean completely lowered or completely raised. All that said, I don't think the OP's top needs a reset because it can perform the raised operation satisfactorily which indicates the program in the controller's CPU is executing code.

The first thing I would do is read and erase diagnostic codes for the soft top controller from socket #10 of X11/4 as explained here: http://www.benzworld.org/forums/r129-sl-class/1266535-diagnostics-sl-pre-94-a.html? Then I would operate the top, read codes once more, and report the ones I found to this thread. If you found no codes, my next step would be to manually unlock the latches for the top bow from within the trunk as explained in your owner's manual. Then I would try to have the top execute the open operation automatically from that point.
 

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Would disconnecting the car's battery for an hour work?
Thinking about this question -- first, my guess is no. And second, I think the reset may have to do with more than just removing power, but I won't speculate any further.

What about the window reset thing?
You don't reset the windows on a 300SL/500SL/600SL. These early cars have limit switches in the bottom of the doors to detect when the windows are lowered. Later cars eliminate these switches and have sensors that count revolutions of the window drive motors. These later cars lose that count when power is lost and require a reset when power is restored.
 

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Discussion Starter #10
Soft Top

I worked on this problem Sunday. After most of the day, manually latching and unlatching the top, I finally got it to operate properly. Monday morning when I tried to lower it, it did the same thing as before. It looks like when I press the down switch, all the latches tighten down, and the then the pump times out. Last night I tried the same process as on Sun, and no improvement. One more thing, as I go thruoght the manual process, unlatch the windshield latches and try the switch, nothing, unlatch the back top, no change, unlatch the bow cover and raise it, now when I try it, the top rises and the bow cover tries to close, hitting the top. It looks like the sequencing is off, is there a way to reset it by checking micro switches or relays, or resetting top module. Thanks for the help.
 

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It looks like when I press the down switch, all the latches tighten down, and the then the pump times out.
I will guess that the controller thinks the hard top is installed on the car because the switch shown in the photo is not closed. This would be confirmed by reading diagnostic codes from the controller.
 

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Discussion Starter #12
Soft Top

After operating the top, manually down and auto up, the code does not change. I get one blink on the red switch. How do I test or over ride that switch to check it ?
 

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You can check all of the switches easily at the soft top controller with a basic electronic multimeter, Greg. The controller is located under a plastic cover in the storage compartment behind the right-side seat. It has three electrical connectors labeled X, Y, and Z. The Y connector is the long one with 35 numbered sockets, and all of the switches are wired to it. With the top, rollbar, and windows all down the following sockets should measure an ohm or less to chassis ground: 10, 20, 21, 22, 25, 26, 27, 29, 31; and the following should be open-circuit: 16, 17, 18, 19, 23, 24, 28, 30. The switch pictured in the earlier post (S84/3) is wired to socket 27.
 

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Discussion Starter #14
Switch, S84/3

Bob,
Thank you for all your info, it turned out to be that switch. The switch was loose in the housing and did not always make contact. The little prongs that mount it to the housing were loose. I cut a plastic rod long enough to force it into the correct position in the housing and hold it there. So fare it has worked every time. Thank you again, you are THE MAN.
Greg
 
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