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Sl 320 1995 silver
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105 Posts
Discussion Starter #1
i have a not working bow extension micro switch, i can hear it clicking raising the rear bow but checking it by a multimeter the circuit is always electrically open, i "manually" closed the circuit for the soft top controller putting a piece of wire to joint the connectors: the microswitch looks always electrically closed this way, no matter what is the position of the rear bow,
and the soft top works, i can open and close it normally...
could it be dangerous any way???
 

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'03 SL Kleemann, 1997 SL320 Pano Top, Tesla Model X
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Stefano,

Lee Wireless is right, of course, in suggesting to get this fixed. The switch signals the top to move at different speeds, depending on the position of the top. (The controller puts hydraulic pressure on both sides of the main lift cylinders to slow them down.) Let's call it crash avoidance.

The switch is electrically closed when the cylinder is retracted.

If you hear something clicking, then either the sound comes from something else but the actual switch inside the micro switch assembly, or you have a loose wire going to the wiring harness connector, or the contacts are broken inside the switch. I have never encountered the latter.

For those readers who have a crushed or bent switch, I have posted the following on repairing bent bow extension switch assemblies before: http://www.benzworld.org/forums/r129-sl-class/1547193-1996-bow-extension-micro-switch-p.html#post4363007

On the photos you have sent me, the switch does not look bent. Thus, let's first hunt for some wire that has come loose. Hope you find it, because this cylinder is the most labor intense to remove, and you need to take out the cylinder to remove the switch. If you decide to take out the cylinder, follow these instructions: http://tophydraulicsinc.com/R129 Bow Extension Cylinder Removal.pdf Make sure to use the 'match trick' described to avoid any damage to the switch assembly when you put it back together.

Hope this helps,

-Klaus
 

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'03 SL Kleemann, 1997 SL320 Pano Top, Tesla Model X
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switch repair

Stefano,

the thread I referenced before, http://www.benzworld.org/forums/r129-sl-class/1547193-1996-bow-extension-micro-switch-p.html#post4363007, gives some info on bending these switches straight again. So far, I have been lucky in that I was able to bend those switches back to be functional.

However, it does not look like yours is bent at all. (You sent me a photo with a top view, and that looked like a switch that had not been bent.)

More likely, you have an electrical problem in your switch assembly, and I'm hoping it is only a wire. You cannot access the tiny switch itself with a multimeter when it is installed on the cylinder. The switch should be electrically closed when the cylinder is retracted. Maybe you could put your multimeter on the two pins at the connector (at the end of the wire coming from the switch; it connects roughly behind the door striker plate) when the cylinder is retracted, and wiggle/massage the wires to see if you suddenly get a switch closed/low Ohms signal from the multimeter.

If you don't find a broken wire or connector away from the switch assembly, you will be stuck taking out the switch, anyway...
 

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Sl 320 1995 silver
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105 Posts
Discussion Starter #8
Klaus i connected the multimeter to the switch connector and the multimeter found the switch is always electrically open even rised or dropped.
 

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'03 SL Kleemann, 1997 SL320 Pano Top, Tesla Model X
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photos of an unbent switch

For everyone who wants to try and bend their accidentally crushed switch back to operational condition - below are some photos of an unbent switch for reference...

-Klaus
 

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'03 SL Kleemann, 1997 SL320 Pano Top, Tesla Model X
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surgery required

Klaus i connected the multimeter to the switch connector and the multimeter found the switch is always electrically open even rised or dropped.
Stefano,

it looks like you're stuck taking it out now, if you were not able to find problems with one of the wires or with the connector...
 

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'03 SL Kleemann, 1997 SL320 Pano Top, Tesla Model X
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temporary fix

You have shorted the connector on the wiring harness already, and that at least made your top operational. Problem is, the top now moves really fast before closing. To keep you operating more or less safely before you get around to working on the switch, you could lessen the impact by letting go of the red switch before the top has reached its target...
 
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