Junior Member

Registered: Dec 2001
Location: st pete fl
Posts: 15
500sl soft top problems
hi, 3 days ago i had all 3 plastic rear windows on my 92 500sl replaced, by the way the price was only 175.00 cheap. now the problem started, the top light remains on and it beeps unsafe, i then put the top up and down many times and now it seems to also be out of sequence, end result, car in my garage with top partialy on. the window man told me he had no idea as to why this problem. please help thanks sven.


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sven

But you are going to have to supply more details. Put the top up completely (by hand if you must). Is the red lamp inside the top switch on? If not lower the top and describe in a reply precisely what you see and where the sequence stops. Now repeat for raising the top: lower the top completely, check the red lamp, raise top automatically if possible and describe precisely what you see.

If you feel up to trying the diagnostics, you should read the article in DIY about evaluating engine controls. It describes how to do "Impulse Testing" with common tools (or an LED and some wire).

Apply the technique to pin 10 of the 16pin diagnostic connector (pass side rear of engine compartment). Read the codes. If you get some codes we will examine them. Eventually you will need the step chart that describes the various steps the top takes and checks off on. The code will usually tell you the last step done successfully.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Sven says when lowering the top the compartment cover closes but the bow/rear window does not lower. This implies the controller does not recognize the cover as being locked.

The controller receives inputs from each lock left and right. These are A24s2 and A25s2 in the documentation. One or both of these switches is probably not closing. This would be confirmed by codes of 2 and/or 3 from pin 10 of the diagnostic connector. Also, with the top completely lowered by hand the red lamp in the top button will be on if either A24s2 or A25s2 is open.

Sven, besides getting the codes I would verify that the compartment cover is mechanically locked. Take your tool for working the locks and manually lock the cover down on either side. You will hear a pronounced "click" as each one locks. Then try lowering the bow automatically. If it works, your problem is not the lock switches.

Disconnected a cable from one of the lock switches on my own car to try and duplicate Sven's problem. When all was back together the red lamp would not go out ever...not with the top completely raised or lowered. Found no malfunction codes and all of the latch swithces checked out. At my wits end. Disconnected the battery and reconnected...light still on. With the ignition on but the engine off, I accessed the top control unit and disconnected the cables to it. Light still on. I verified proper inputs from the lock swithes at the control unit. When I reassembled the cables, the lamp went out. Everything is fine...

I suppose cycling power to the control unit did the trick. But why disconnecting the battery did not work but disconnecting the cables did I have no clue.