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1990 500SL
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86 Posts
Discussion Starter #1
Hi Guys,

Hopefully I can get some help with this.

I bought this 90' 500SL a few months ago, and finally Im going to insure it and enjoy it for a bit. While the weather is still good.

I bought the car from my boss last year, and the convertible roof was working fine. He actually got the hydraulic pump sent out to be rebuilt apparently. I saw it working flawlessly before.

Today I took the hard top off, put it on the stand, and tried to make sure that the soft top operation was still good.

The soft top opens up and moves fine. Until it gets to around the 1/3 or 1/2 open mark, then it acts like its stuck. It tried to go further, than back, open/close.

I can't spot anything "stuck". I searched for a bit and some said it could be low voltage (i dont think so), re-syncing windows/locks (they all work). I did take the battery out last week to put it on the trickle charger. Otherwise everything seems okay.

Any advice? i hope its not something terrible expensive or complex (hydraulic wise, or the top module).

Thanks in advance.

-Rod
 

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Registered
1990 500SL
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86 Posts
Discussion Starter #3
Try it with the engine running
tried with engine running to begin with, then engine off position 2, then engine running again. tried both sets of keys. Unlocked, locked car, roll bar up, roll bar down. Fuses are brand new and good. The windows and doors work fine, but I disconnected the battery from it a bunch of times while it sat. Is there anything to re-sync?

Thanks for your input.
 

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Departed 1998 SL500 (and the Pano is in Bogota)
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11,112 Posts
If things are out of sync, the roof will not start to move at all, so something else was wrong.
May do a diagnostic scan
 

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Registered
1990 500SL
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86 Posts
Discussion Starter #5
I have also tried to run it at a higher rpm. 1500/2000 RPM. Holy hell does the top actually function a lot quicker! but still no fix. It's definitely feels like it stuck somewhere.

Sorry for a noob question, but how may i start a DTC scan? is this something I can do myself at home?
 

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Registered
1993 600SL, 1973 450 SL,1982 380SL,1998 SLK 230, 1968 Firebird, 2001 Dodge Ram 4x4,2005 Ford Escape
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5,247 Posts
Does the pump continue to run when the top stops ? the control system diverts fluid to both sides of the main lift cylinders to slow the decent of the top. Due to the space the rod takes up, that side is over powered by the side that has no rod. If that cylinder has bad seals, perhaps the fluid is bypassing and the top stalls. If the pump stops, perhaps its a micro switch issue. You need to check with Klaus @ Top Hydraulics. He's the top guru. He runs perhaps the most helpful value priced operation you will ever find in BenzVille. There are no free lunches but he is honest and beyond helpful to anyone who needs his expertise. Search that name and you'll be glad you did !
 

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Departed 1998 SL500 (and the Pano is in Bogota)
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11,112 Posts
I agree with Tdoroit, sound like a sensor (switch) problem not sending the correct signal to the controller. I am not familiar with doing diagnostic on the early R129 (as I just hook up a scanner to the 38-pin port in my '98), should check with Klaus.
 

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Registered
1990 500SL
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86 Posts
Discussion Starter #9
i haven't checked to see if the pump still runs when the top stops.

today with the help the help of my father and a friend, the soft top is able to come up and attach with some force.

my friend noted that its was probably a bad idea to store the car with the soft top down and the hard top on.

When the car is moving the convertible roof switch is flashing, but when it stops and the brakes are held, the switch light just stays on.
 

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1990 500SL
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86 Posts
Discussion Starter #10
so the top can go up and down with assitance (basically manual).

i have located a problem (or part of it).

The back part of the soft top (rear windows, etc) doesnt seem to lift up, but it will lift down. Everything else works properly, and latches properly.

Hydraulic fluid is full, I dont believe there is a leak. I saw a sensor on the driver side for section of the rear soft top. What sensor is this? and is it prone to failures?
 

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Registered
1990 500SL
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86 Posts
Discussion Starter #12
just wanted to update this thread and say that the problem i was experiencing was with the convertible roof control module itself (the one underneath a cover behind the passenger seat in the storage space). I bought/tried another module, and it my convertible roof worked like a charm. Hopefully it will continue to do so :)

thanks for the advice given here previously.

and a pic of the beauty...

 
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