SL/R129: 1991 300SL Soft Top Problem
Thread Starter
Newbie
Joined: Sep 2002
Posts: 2
Likes: 0
From: Dublin, Ohio
1991 300SL
1991 300SL Soft Top Problem
I am searching for a shop manual that will allow me to trouble-shoot my soft top control problem. When I move the switch to lower the top, all I get is the blinking light in the switch. The SL has very low mileage and is in excellent condition. I am an experienced MB do it yourself fixer upper as well as an electrical engineer.
If I can locate a schematic, sequence of operation, and limit switch location chart I am confident I can isolate the problem. I do not want to just replace the $1,100.00 control unit until I have eliminated all other devices.
Are rebuilt or used soft top control units available?
I am also interested in any and all technical tips and known problems associated with the 1991 300SL since I plan to keep the car in operation for many more years.
I have read about the front shock tower mounts and inspected my and they are in good shape.
The head gasket was replaced 5K miles ago along with the front engine cover gasket and injectors.
If I can locate a schematic, sequence of operation, and limit switch location chart I am confident I can isolate the problem. I do not want to just replace the $1,100.00 control unit until I have eliminated all other devices.
Are rebuilt or used soft top control units available?
I am also interested in any and all technical tips and known problems associated with the 1991 300SL since I plan to keep the car in operation for many more years.
I have read about the front shock tower mounts and inspected my and they are in good shape.
The head gasket was replaced 5K miles ago along with the front engine cover gasket and injectors.
Senior Member
Joined: Feb 2002
Posts: 330
Likes: 1
From: Kingdom of Bahrain
R129 500
soft top..
hello there,
I did had the same problem ( blinking light in the switch)...
it was from the car battery, it was week,
and when i change it, it worked fine..
check how old is the battery and try it..
Regards..
I did had the same problem ( blinking light in the switch)...
it was from the car battery, it was week,
and when i change it, it worked fine..
check how old is the battery and try it..
Regards..
MBWorld Fanatic!
Joined: Jul 2002
Posts: 2,447
Likes: 14
From: UK
SL55 AMG
The voltage suggestion is a good one. The roof uses a number of solenoid operated valves and locks to operate and these need proper power to run. Try operating it with the engine running.
The main roof is operated by the hydraulic pump in the spare wheel well in the trunk. Make sure this is in good condition and all fuses etc are intact. Check the connector is OK and all the cables are properly seated in it. You can clearly hear the pump running. Remember the 129 has multiple fuses boxes, you need to check the one in the trunk by the right hand trunk lid hinge/strut
If the light flashes it means that one or other condition for the roof to lower is not being satisfied, most likely a sensor.
It beggars belief that Mercedes charge $1100 for this unit. It must contain all of $20 of components.
The main roof is operated by the hydraulic pump in the spare wheel well in the trunk. Make sure this is in good condition and all fuses etc are intact. Check the connector is OK and all the cables are properly seated in it. You can clearly hear the pump running. Remember the 129 has multiple fuses boxes, you need to check the one in the trunk by the right hand trunk lid hinge/strut
If the light flashes it means that one or other condition for the roof to lower is not being satisfied, most likely a sensor.
It beggars belief that Mercedes charge $1100 for this unit. It must contain all of $20 of components.
Thread Starter
Newbie
Joined: Sep 2002
Posts: 2
Likes: 0
From: Dublin, Ohio
1991 300SL
Thanks to Blue SL.
I have acquired a schematic and will check out the items you suggested.
I have also replaced the battery.
I have hope that I will find and fix the problem.
I will post a report.
Thanks to all
Dan
I have acquired a schematic and will check out the items you suggested.
I have also replaced the battery.
I have hope that I will find and fix the problem.
I will post a report.
Thanks to all
Dan
Newbie
Joined: Oct 2005
Posts: 4
Likes: 0
top problem - solution
Check this out http://www.benzworld.org/forums/r129...ghlight=SLOVER
Had the same problem and solved it by myself and posted it on the forum
good luck
Had the same problem and solved it by myself and posted it on the forum
good luck
Banned
Joined: Jan 2006
Posts: 1,982
Likes: 393
From: Atlanta, unfortunately
'09 S600, (2) R129 300SLs, '03 SL500, '03 SL55
If you check diagnostic codes on the top controller you will likely know precisely what your problem is. You need no tools at all to do this...Just a wire or paper clip to make an electrical connection.
The code retrieval method for the top controller as described here works for cars produced through 12/93. A similar procedure can be used for cars produced from 1/94 through 8/95.
The diagnostics are wired to sockets of the car's main "diagnostic connector", X11/4. These are numbered from 1 to 16. The top control system diagnostic is socket #10. The connector is located on the left side of the car just behind the strut mount. It should have a plastic cover over it (picture).
Codes must be read one at a time. That is, you ask the system to issue a code, you read the code, you ask for another code, and so on. You ask a particular system for a code by electrically shorting the diagnostic socket to ground for 2 to 4 seconds. A second or two after the short is removed, a series of electrical pulses will appear at the socket. The number of pulses corresponds to the number of a code. The ignition must be switched-on for this process.
There are many ways to view the pulses for counting and reading codes. The simplest method is to watch the lamp inside the top switch flash. This is possible because one side of the lamp is wired to the diagnostic socket for the top control system.
Once you have read all of the codes, you may wish to go back and erase them. They are erased individually one at a time. To do this, read a code, wait a few seconds, and then short the diagnostic socket to ground for 6 to 8 seconds.
The code retrieval method for the top controller as described here works for cars produced through 12/93. A similar procedure can be used for cars produced from 1/94 through 8/95.
The diagnostics are wired to sockets of the car's main "diagnostic connector", X11/4. These are numbered from 1 to 16. The top control system diagnostic is socket #10. The connector is located on the left side of the car just behind the strut mount. It should have a plastic cover over it (picture).
Codes must be read one at a time. That is, you ask the system to issue a code, you read the code, you ask for another code, and so on. You ask a particular system for a code by electrically shorting the diagnostic socket to ground for 2 to 4 seconds. A second or two after the short is removed, a series of electrical pulses will appear at the socket. The number of pulses corresponds to the number of a code. The ignition must be switched-on for this process.
There are many ways to view the pulses for counting and reading codes. The simplest method is to watch the lamp inside the top switch flash. This is possible because one side of the lamp is wired to the diagnostic socket for the top control system.
Once you have read all of the codes, you may wish to go back and erase them. They are erased individually one at a time. To do this, read a code, wait a few seconds, and then short the diagnostic socket to ground for 6 to 8 seconds.
Last edited by bobterry99; May 11, 2006 at 02:42 AM.
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