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2003 G500, 2000 SL500, 1995 E320 Cabriolet, 1980 TR8
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Discussion Starter #1 (Edited)
Does anyone know whether the contacts for the cabriolet windshield header top latched microswitches are open or closed when the header latches are locked? I have a top fault which may be related to the header latches.

Thanks!
 

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W124 Moderator
86 190E 2.3L 16V, 2 95 320TE's, 02 S500
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Does anyone know whether the contacts for the cabriolet windshield header top latched microswitches are open or closed when the header latches are locked? I have a top fault which may be related to the header latches.

Thanks!
Shoot a PM to LeftCoastGeek.. he'll have the answer.

Jayare

Sent from my XT1710-02 using Tapatalk
 

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Premium Member
1993 300CE Cabriolet (mine) ; 1994 E320 Wagon (wife's) ; 1990 Benz 300E 2.6 (son's)
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ya know, I probably could pull my back seat, and the top controller, and ohm the wires to the switches at the connector into the top CU... but not tonight, its pouring out there, and probably not tomorrow as the rain continues.
 

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2003 G500, 2000 SL500, 1995 E320 Cabriolet, 1980 TR8
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Discussion Starter #5
Left Coast - thank you for the schematic and for your offer to ring out the switches, but I'm going to just have to put my back seat and do it. It's not raining here, but the temperature is a balmy 35 degrees so I have been trying to avoid it. Thanks again for everything!
 

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2003 G500, 2000 SL500, 1995 E320 Cabriolet, 1980 TR8
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Discussion Starter #6
Well, it warmed to to 40 here today so I went out and rang out the header switches. The contacts are closed (which means the control lines are grounded) when the top latches are locked. Unfortunately for me, mine are working perfectly so that means I have a top controller failure as the cause of my top light being illuminated at startup. I'm going to try and clean things with some PCB cleaner (which about the limit of what I can do with a module which is mostly SMD) and see if that helps, but I guess the search will be on for a new controller. Bummer.
 

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1993 300CE Cabriolet (mine) ; 1994 E320 Wagon (wife's) ; 1990 Benz 300E 2.6 (son's)
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do your windows go down when you tell it to put the top up or down ? I believe the top controller needs a signal back from the CF module to do this, and that CF module is a special convertible-only version.

there's also a whole pile of limit switches on the tonneau cover and its latch, the bow frame and its latch, the main lift, that all have to read correctly for it to step through its cycles...
 

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2003 G500, 2000 SL500, 1995 E320 Cabriolet, 1980 TR8
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Discussion Starter #8
When the top was working, the windows rolled down/up as they should with the top. Yes, there are two control lines between the soft top controller and the CF module that allow them to "speak" to coordinate the window movements. They use two of the contacts that are normally used for the sunroof control on other cars, thus making the cabrio CF module a dead special unit.

It has been my experience with the W124 and the R129 that if the other various microswitches are in an erroneous state, you will get a flashing top button light, not a steady one like I have. Since for the time being, the cabrio must be outside, I have not been able to "cycle" the roof at this point as I am afraid it may not be able to close again. I will be able to do more diagnostics once I can get it into the (under construction) garage.
 

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1993 300CE Cabriolet (mine) ; 1994 E320 Wagon (wife's) ; 1990 Benz 300E 2.6 (son's)
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btw, you ever look inside that Cabrio top controller box?











I looked up what all those parts are.... the 5 pin 'transistor' looking things standing up in that last pic are the power drivers for all the actuators. The Toshiba TA7900S on the far left of the last pic is a "5V voltage regulator with watchdog timer".

the big Siemens square chip on the other board is an 80C51 family CPU. the Signetics 27C256 next to it is a 256kbit EPROM, probably the firmware. that bunch of motorola 14512B's, those are 8 bit 'data selectors', each one can select from 1 of 8 input lines, probably used to read all the limit switches. the 74HC259's are 8 bit addressable latches, probably used to send control bits to the other power board.

I poured over this thing with a magnifier and bright lights, and saw no sign of overheating, fried anything, cooked/leaky caps, bad solder joints, nada. but it didn't work, and the replacement did.
 

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2003 G500, 2000 SL500, 1995 E320 Cabriolet, 1980 TR8
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Discussion Starter #10
Thank you for the detailed info and the pics! I'm going to do a careful inspection of mine to see if I can see anything that has gone awry internally. But like you, I suspect everything will "look" normal. Do you happen to know if error codes/conditions are stored in NV ram or do they get wiped out on loss of power?
 

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1993 300CE Cabriolet (mine) ; 1994 E320 Wagon (wife's) ; 1990 Benz 300E 2.6 (son's)
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sigh, I saw a document somewhere on the diagnostic box for the soft top controller, it had passthrough connectors for the X,Y,Z(?) plugs on the controller, and a breakout box of LEDs and pushbuttons that you could use to simulate the top. I don't remember if it had error codes or not, but for sure they are NOT wired to the main diag block under the hood.

the wiring diagram shows a soft top diagnostic connector X11/12 (4 pin) but the connector locator doesn't show where this is. for some reason, the rollbar fault light IS connected to the main 16 pin diag block X11/4


oh.... here, http://www.w124performance.com/docs/mb/diagnostics/DTC_List_W124_M104.pdf mentions this connector
rollbar blink codes on page 17
X11/12 top controller diag connector and impulse codes shown on page 22... note the red wire that is shown to X11/4 pin 16 is just power, as they suggest you can get that from x4/10 under the dashboard so you don't need to run wires to under the hood. x11/4 pin 1 is ground, so any nearby ground is good.
 

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2003 G500, 2000 SL500, 1995 E320 Cabriolet, 1980 TR8
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Discussion Starter #12
Thanks again for the info.

I have been studying the W124 soft top troubleshooting manual and its seems that the bow switch can also cause this kind of error (news to me). It seems I will have to do some more investigating before condemning the top module.

2612593
 

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1995 W124 E320 Cabrio
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question: does Becker Autosound service the top control modules? Or the alarm module? Or only the stereos & amps?

I noticed the Becker logo is all over on these cars--
 

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1993 300CE Cabriolet (mine) ; 1994 E320 Wagon (wife's) ; 1990 Benz 300E 2.6 (son's)
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Thanks again for the info.

I have been studying the W124 soft top troubleshooting manual and its seems that the bow switch can also cause this kind of error (news to me). It seems I will have to do some more investigating before condemning the top module.
afaik, you can use one of those led+pushbutton blinkers to read these codes. just count the blinks after a 1 second push of the button, same as with the codes off the X11/4 engine etc diag box under the hood....

question: does Becker Autosound service the top control modules? Or the alarm module? Or only the stereos & amps?

I noticed the Becker logo is all over on these cars--
pretty sure they only fix the audio stuff but you could ask them. I'm not even sure they are affiliated with the actual Becker (if that even still exists?). Ah, in 1995, the US company Harman International (Harman-Kardan, JBL, Infinity, and many other brands) acquired Becker of Germany, and in 2017, Samsung acquired Harman. :-/
 

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2003 G500, 2000 SL500, 1995 E320 Cabriolet, 1980 TR8
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Discussion Starter #15 (Edited)
According to the troubleshooting manual, DTC codes are only stored when the soft top light is flashing, a point that I have not reached yet with mine. I am really hoping that I can get soft top controller to at least open the rear bow latch so that I can inspect/test the rear bow lock microswitch. It's an unbelievable PITA to get things opened up if that latch won't release hydraulically. I have attached the procedure that I worked out for doing this in case someone needs to do it someday.
 

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Premium Member
1993 300CE Cabriolet (mine) ; 1994 E320 Wagon (wife's) ; 1990 Benz 300E 2.6 (son's)
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you might note, those connectors on the top controller are in fact labeled X, Y, Z, corresponding to your 1,2,3
 

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2003 G500, 2000 SL500, 1995 E320 Cabriolet, 1980 TR8
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Discussion Starter #17
you might note, those connectors on the top controller are in fact labeled X, Y, Z, corresponding to your 1,2,3
If I can find the Word file for that PDF I will relabel them so that they are correct.
 

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'92 300TE 4matic 280,000miles, '92 300TE 4Matic 'Ice Blue Metalic' 101,000miles
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Whoa....that controller box....what could possibly go wrong in there....:whistle:

Kevin
 

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2003 G500, 2000 SL500, 1995 E320 Cabriolet, 1980 TR8
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Discussion Starter #19
2612729


Hmmm, it could be a while before I can complete the diagnosis . . .
 
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