1996 SL500 electric windows and convertible top
 

When I open either door, the window which was in the full up position automatically lowers itself 1/3 the way...the only remedy is to reset the the windows by depressing the up/down button until you hear a click. This remedy, however, only lasts a short while. The window reset technique also must be done to ensure the complete cycle of lowering and raising the convertible top. What's up (no pun intended)?

Adrian

window drop function and window synchronization
 

Adrian,

welcome to the forum! That's an annoying situation. When the windows get "out of synch", that means the controller needs to relearn their positions. The reason is, the window position in model '95 - '02 is not determined by micro switches (as in model years '90 - '94), but by counting the turns the window motor makes. The motor's turns are counted through a magnetic "Hall-sensor" on the motor shaft, and the controller is relying on it's memory of turns counted back and forth.

If the battery voltage runs low or the battery gets disconnected for an extended period, then the controller looses its memory, and it needs to relearn the window position by going through the synchronization process described in your owner's manual. The controller is made to retain its memory for at least an hour if supply voltage is absent or too low. The soft top will only move automatically when the controller "knows" where the windows are, and they have to be down for the soft top to move.

Has there been any problem with your battery lately?

-Klaus

klaus@tophydraulicsinc.com

Klaus: thank your for your quick reply. Yes, I recently had the battery die for several days before it was replaced; also reset the radio code, and the windows according to the owners manual. However, the windows continually need to be reset; each reset only lasts a short period of time. I wonder if the winodw crank magnet system is the problem, in that, it won't hold its memory! Adrian

controller problem?
 

Adrian,

The soft top controller controls the windows and the top hydraulics. It also controls the roll bar function in models '95+. That means, for example, if you push a window switch, the signal will go to the controller and it supplies the voltage directly to the window motors. It is also the same controller that reads out all the signals from the window motor sensors and all the other micro switches dealing with the convertible top.

If we look at the chain of events here, then it is likely that there is not a wiring or sensor issue (unless your windows or electrical system have been "worked on" lately).

Do the battery poles have good contact (meaning, have you had starting problems after the battery was replaced?), are there any other electrical problems, or has the engine been run without a battery connected?

-Klaus

klaus@tophydraulicsinc.com

Klaus: good battery contact; no other electrical problems...the condition existed before replacing dead battery. The roll bar always functions properly. It's the windows and the soft top coordination: the windows need to be reset after every ignition off or they automatically open 1/3 distance when you open door; however, this will not occur "if" you open door before you turn ignition off - then on restart the windows act normal and do not have to be reset. And, in order to ensure the complete lowering of the soft top you need to reset the windows or it may just stop halfway in the cycle - very embarassing. If you reset the windows before moving the soft top (up or down) then it completes the cycle as it's supposed to!
You're very kind to analize this from me,.
Thanks, Adrian

what caused the controller problem?
 

Adrian,

The roll bar should work independently of window position, but not while the top up or down cycle is unfinished. That part is okay.

What I'm reading here about the consistent need to reset is concerning. Since the problem does not occur if you open the door before turning off the ignition, I don't think there is a problem with the readout. That leads us straight to the controller malfunctioning. I have heard of somewhat similar behavior with the windows when the controller has been exposed to voltage spikes before - that's why I asked earlier whether the car had ever been run with the battery disconnected. The battery acts as a buffer for voltage spikes from the alternator... Also, if batteries get connected or disconnected in the wrong order, there can be problems. (Disconnect: always disconnect only negative, or disconnect negative first. Reconnect: Always reconnect negative last)

One simple experiment you could make, is to disconnect the negative battery pole at least over night; ideally longer. That could erase some fault codes stored in the controller and making it act up. There could also be some previous and possibly even current error codes from the soft top operation interfering, but I don't want to complicate my response here too much. If the reset via battery disconnect doesn't work, next step is to send the controller to BBA for diagnosis and repair estimate. That's cheaper than going to the dealer for a code read, but it takes longer.

The controller is located under the right rear compartment. Always disconnect the negative battery terminal before removing the controller. One 10-mm wrench, and you're ready to take out the controller to send it in, if you have to. Let's hope you won't have to, because rebuilding '95+ controllers is often not possible.

-Klaus

klaus@tophydraulicsinc.com

Klaus: I'll try the negative battery terminal disconnect for as long a period as possible (at least an over-nighter) and get back with you.

Again, thanks.
Adrian

trick to reset the RST controller memory faster
 

I have had the controller still misbehaving on the windows even if the battery was disconnected over night, but working fine after disconnecting for several days.

One trick to speed up the memory reset: AFTER disconnecting the negative terminal, run a wire from the positive terminal to the disconnected, loose negative battery cable - just don't forget to remove that shorting wire (shunt) before reconnecting the negative terminal to the battery...

-Klaus

klaus@tophydraulicsinc.com

Klaus: the overnight (22 hours) with the jumper technique, unfortunelty, did not work. I will try for a longer period (perhaps over this weekend).
Thanks,
Adrian

having a similar issue with a 1997 500SL. I had a new top installed by a local upholstry shop. brought it home to me this evening and no joy.. both the roll bar switch lights and top control button lights steady on when key is turned on. I'm not having the same issues with windows.. but they are stuck down. I suspect he may have been recycling the top with the engine off and ran the battery down.. Any thoughts? Anyone? Anyone? Bueller?

more details, please
 

Mariner,

welcome to the forum! It would be nice to see your location in your profile.

In order to help you out, we need more details.
- Did you receive the car with the windows stuck down?
- What position is your top in now?
- Are you able to move the windows up with the window switches (and if so, have you performed the window synchronization as described in the owner's manual)?

Klaus

klaus@tophydraulicsinc.com
www.tophydraulicsinc.com

the windows are working ok.
I can lower the top completely and close the lid manually.
the rearmost latches seem to be stuck, so that the top cannot be closed "up" all the way.
Right now the top is as up as I can get it.
the lights on the roll bar switch and the light on the top button are steady on
when the car gets turned on.

I wish I had an owners manual ;)
bought it used.. very little documentation came with it.

rear locks stuck closed?
 

Mariner,

here is where you can download an owner's manual: http://www.benzworld.org/forums/r129...ml#post2391320

I don't fully understand the description. Could you repeat it and be very precise about what is working automatically, and what isn't? Small details can give important clues.

For example, if in your model year one of the rear locks should be closed (will not accept the prongs from the rear of the soft top), then we have likely already found the culprit...

Also, please confirm whether your windows drop a fraction of an inch when you open the doors.

Klaus

klaus@tophydraulicsinc.com
www.tophydraulicsinc.com

nothing is working automatically right now except the windows.
the roll bar is non-functional.
the soft top mechanism is non-functional.
the hard top latch down is non-functional.
the red lights on the roll bar and the light in the soft top button on the console are "steady on" when the car is turned on.

>>For example, if in your model year one of the rear locks should be closed (will not accept the prongs from the rear of the soft top), then we have likely already found the culprit...<<

BINGO!!!

I can't get the prongs down into the receiver on either the soft top or the hardtop

the windows do their little drop down trick when the doors open and close

One or two rear locks closed in model year '95+ can freeze the controller
 

Mariner,

that's actually good news about the rear locks not receiving the prongs! I have emailed you a link to instructions I have written for another forum, and will add a similar, updated post to this thread shortly.

In a nut shell, we are dealing with a design flaw on '95+ model years freezing the controller when one or both rear locks accidentally get locked without the rear of the soft top being pulled down. This normally happens only when people take of their hard tops and don't push the red button forward long enough.

Hope that will take care of your problem,

Klaus

klaus@tophydraulicsinc.com
www.tophydraulicsinc.com

Klaus, I took a stab at resetting the locks this evening, but it was getting dark, and I was getting frustrated.. they didn't seem to catch "up".
i took it to my mechanic and dropped it off. When I get it back I'll post what the final fix was.

Thanks for trying.

Apparently the new top was installed just a wee bit too tight, so that when the front of the top tried to lock, the front locks couldn't engage completely which through the whole mechanism out of whack. having to leave the top up for a couple weeks to see if it will stretch out a little.
if not, then it's back to the installer to pound on him to try again.

Hi All, I'm new to this, so I hope I have the right ettiquette! I have recently "inherited" a 1995 SL320. It's a real beaut, but the only thing is, that the soft top and the windows don't seem to work! When you try to lower the soft top, you can hear it trying to work, and it seems to click, but after that, nothing - it doesn't open at all. Also, both windows don't work at all, not even a noise...when it first happened, I disconnected the negative on the battery for 2 mins, then re-connected and it worked fine....but then as soon as I turned off the engine, it didn't work again - and now after doing this a couple of times, it doesn't work at all anymore - and it's bloody hot!
Can anyone help me please?

many thanks
Shaggy

window synchronization and/or rear locks in opposite position??
 

Shaggy,

welcome to the forum! Do you have an owner's manual for your car? It shows you how to synchronize the windows after you had a drained or dead battery. Since your windows don't work at all, you have more problems to solve, and I will address that below.

The top will not work if the windows are not synchronized on model years '95 and younger. You know that your windows are synchronized if the windows drop a fraction of an inch after you open the doors.

Just for completeness, here is the procedure in a nutshell:

With the top fully up and locked in front and rear, or with the top fully down and the tonneau cover locked,
1) doors closed
2) trunk (boot) lid fully closed
3) engine off
4) run the windows down and up again. in the up position, holds both window switches for some 5 seconds. Done.
5) Check that the windows drop a fraction of an inch when you open the doors.

The windows will not move if your top is not fully closed and locked or fully open. You can manually lock the front locks with a 6-mm Allen wrench. On early '95 models, you can manually lock the rear latches with the 10-mm open wrench part of the soft top tool. On later '95s and up, it gets a bit more complicated.

What I am concerned about in your case is whether one of your rear locks isn't accidentally closed with the rear of the soft top resting above it. That would freeze the controller and explain the behavior you are describing.

Please let us know what you find, and we will take it from there...

Klaus

www.tophydraulicsinc.com

Hi There! thanks for the reply!

Yes - I have a manual, and I have seen from lots of other posts how to synchronize the windows, but as you point out, I can't use the windows, so I can't synchronize them...!

So - update - I removed the negative lead from the battery last night for half an hour - and then re-connected it (saw this on another thread on here) and sure enough, when I reconnected to negative lead to the battery, I was able to drop the windows! However - this only worked once, and once the windows were down, they would not go back up (and the roof would not move again). So then I had to do this again (dis-connect, reconnect etc) just to be able to do the windows up again - and again, after this one operation, the windows/roof froze (closed this time luckily!!).

So now I am stuck again! when I open the doors, the windows definitely do not move down at all - and neither the windows or roof work...and i'm missing this lovely sunshine in the UK!!!

The only other thing I can say is that when I try to take the roof down, the red light on the controller flashes/blinks until I stop pressing it back.

Any ideas?! thanks, Chris

How long to disconnect the controller
 

Sorry about your bad luck. One more question before I blame the controller:
- Does the warning chime up by the rear view mirror go off when you first start driving the car? (If that was the case, it would indicate a partially closed top, and this would be the easier problem to fix.)

I am glad that you are disconnecting only the negative terminal on the battery - never disconnect the positive one first!

About disconnecting the battery: If you disconnect the battery, you can erase some volatile memory in the soft top controller (which also controls the windows and the roll bar), and that sometimes helps out. In particular, controllers from model years '95 and up can easily get an overload of error messages and end up freezing the soft top operation. However, the volatile memory can easily stay stored for hours with the battery disconnected, so I would disconnect the battery over night before declaring the controller compromised.

The soft top controller controls the windows, and power for the windows goes directly from the controller to the window motors. If you are desperate to move your windows, you will have to access the junction where power is supplied to the window motors. It's behind the door panel right under the side view mirror.

Please let us know what you find after an extended battery disconnect. If nothing changes and the chime doesn't go off when you first start driving, I would recommend next to have someone with Star Diagnosis read codes from your controller or you send it in for evaluation (which can be cheaper than reading codes...).

Klaus

www.tophydraulicsinc.com

1997 SL280 windows auto drop issue
 

Hi Klaus,
I'm a new member of this forum and learned that you are the expert in SL convertible area. I'm hoping I can pick your brain/advices to resolve some of my little unhappiness.
I'm having same issue as Adrain encountered a year before (Jan 2012).
1) When I open either door.
2) The window was in the full up position, automatically lowers itself 1/2 way instead of normally 1/2 of inch.
3) I then re-sync the window and works normal again.
4) After 3 to 10 days, same issue happens again. Re-synchronization required again to get back to normal.
Some background infos:
- My car have done 55K km in 16 years. NO any major problem/accident before.
- The windows issue has been happening around 3 or 4 months ago.
- The battery has been replaced 3 years ago.
- A major services 6 months ago and my car stayed with my mechanic for 2 weeks.

Klaus, hope you can help to advice to address my issue. Btw, did Adrain's issue has been resolved after disconnected the battery for an extended period?

Thanks,
Victor

Victor,

sorry to hear about your trouble. I am not aware of any cases where windows need to be resynchronized (and where the synchronization fixes the problem) other than after a battery has been low or disconnected. The synchronization means that the controller's memory of the window position gets refreshed. That happens after the battery has been very low or disconnected. My first guess in your case is a loose connection somewhere, or oxidized contacts on the battery.

Have you had any trouble at all starting the car, and do you have to re-enter the radio code from time to time?

Klaus

www.tophydraulicsinc.com

Hi Klaus,

Thanks for your prompt response. I've briefly checked this morning (Sydney time) that there are no obvious sign of loose connection and a clean contacts on the battery. But I also checked that the battery is roughly only 12 volts before the engine starts and roughly 13.5 volts when the engine started. Is the battery too weak? Btw, the window drops 1/2 way this morning which I had re-synchronized the window a day before.

The engine starts ok without any trouble (3 to 5 cranking) and I don't have the original Mercedes radio so no code is required.

What's next I can do?

Thanks,
Victor

Victor.km.lam,

this is a tricky one. If your starter cranks, then certainly the battery voltage is not too low to maintain the memory inside your soft top controller (most likely a p/n 1298203926 in your '97 SL280). A good battery will have about 12.6 Volts at the terminals, btw. The reason I asked about the radio code was to figure out how far the voltage drop was spreading, if a voltage drop is really the issue.

Next question: do you have rodents in the car, by chance? The right storage compartment behind the seat is a favorite hangout and nesting place for mice, if they have made it into your trunk area somehow, and the soft top controller is located under the right storage compartment.

I would advise removing the plastic piece on the bottom of the storage compartment (see instructions in the picture below) and checking the area around the controller for obvious signs of damage or corrosion.

Klaus

www.tophydraulicsinc.com