tmwsccsh
Active Member
- Joined
- Sep 8, 2012
- Messages
- 323
- Location
- Letchworth, Hertfordshire
- Car
- 1998 CL420, 1994 Ford Mustang Convertible
All,
Firstly, apologies that this is going to be a bit of a long one – there’s a fair bit of background to go through alas.
I have put postings up earlier this year with regards to problems with the roof mechanism on my 1995 SL500. I decided to bite the bullet and took it to an MB specialist in the town to get it properly diagnosed and sorted around 3 months ago. The roof had got to a point where all I had was a flashing red light on the roof button inside the car and the red lights on the roll-bar switch were also illuminated.
After a couple of weeks of the car being at the place, the roof control module was believed to be the cause of the problem. Owing to the extortionate cost of new ones of these a 2nd-hand one with a warranty was sourced and promptly fitted to the car. We had movement!
Unfortunately though, there was still a problem in that the mechanism would not lock in to place or return the windows to their natural position. It was also noted at the time that the windows were not dropping upon opening the door as would be expected.
Further investigations and the window motors had to be replaced. One sourced in the UK, one sourced from the USA (as I couldn’t get one at a sensible price over here) and they arrived. Fitted and the windows came back to life and were working fine. However, the whole mechanism was still not functioning as expected.
I know that some work was done to bring the mechanism to life and, after some jiggery-pokery all is good and working. Well, we thought it was. The car is currently at a point where the roof works exactly as it should for 3 cycles and then, at the time the windows are going back up again, they stop around half-way up and won’t move beyond that. Trying to move them with the window switch also does nothing – they are just stuck there. The only way that they will budge again is for the battery to be disconnected for about 30 minutes – after that the system has “reset” and all works again. Until the 3rd cycle and then the windows stop half-way up. And so the pattern repeats…
Interestingly, a fault code is being emitted from the windows:-
“Side windows S21/9 down limit switch L”
“Side windows S21/8 down limit switch R”
But the confusion comes in that the car does not have down limit switches in the door – the limit switch is built into the motor. Which adds another dimension – according to Mercedes, the chassis number gives that the car should have limit switches in the door, but they definitely are not there. And at this point we are at a loss…
They have spoken with a main dealer to see if they had any ideas and, by co-incidence, they actually had a similar fault on the same model a few weeks ago. The issue was resolved on that one by replacing the Window Motors again with genuine Mercedes ones where the 2nd hand sourced ones (as with mine) were not working (overall symptoms were exactly the same and the same steps and replacements had been done as with mine – even to the point of saying it should have the limit switches in the door but didn’t).
I did ask if, when the testing is being done, it is being a down-up-down-up-down-up attempt (so the 3x movements all at the same time) or if there is a gap between them being done to simulate “real life” (so put the roof down, leave it a couple of hours, put it back up, leave it a couple of hours, put it down again, leave it, etc.) but I have been told that has been done already and, again, on the 3rd cycle it failed in the same way.
So, my questions / thoughts are...
- Why does it work fine for 2 passes and fail on the third, every time? Suggests a heating / shorting issue somewhere to me?
- Is replacing the Window Motors again going to solve the problem?
- How do we know it is not the roof control module (as I have been told the windows pass through that)?
- Has anyone else had similar problems in the past and know of any other options to solving?
Thanks in advance for any pointers / guidance.
Regards
Tim Watts
Firstly, apologies that this is going to be a bit of a long one – there’s a fair bit of background to go through alas.
I have put postings up earlier this year with regards to problems with the roof mechanism on my 1995 SL500. I decided to bite the bullet and took it to an MB specialist in the town to get it properly diagnosed and sorted around 3 months ago. The roof had got to a point where all I had was a flashing red light on the roof button inside the car and the red lights on the roll-bar switch were also illuminated.
After a couple of weeks of the car being at the place, the roof control module was believed to be the cause of the problem. Owing to the extortionate cost of new ones of these a 2nd-hand one with a warranty was sourced and promptly fitted to the car. We had movement!
Unfortunately though, there was still a problem in that the mechanism would not lock in to place or return the windows to their natural position. It was also noted at the time that the windows were not dropping upon opening the door as would be expected.
Further investigations and the window motors had to be replaced. One sourced in the UK, one sourced from the USA (as I couldn’t get one at a sensible price over here) and they arrived. Fitted and the windows came back to life and were working fine. However, the whole mechanism was still not functioning as expected.
I know that some work was done to bring the mechanism to life and, after some jiggery-pokery all is good and working. Well, we thought it was. The car is currently at a point where the roof works exactly as it should for 3 cycles and then, at the time the windows are going back up again, they stop around half-way up and won’t move beyond that. Trying to move them with the window switch also does nothing – they are just stuck there. The only way that they will budge again is for the battery to be disconnected for about 30 minutes – after that the system has “reset” and all works again. Until the 3rd cycle and then the windows stop half-way up. And so the pattern repeats…
Interestingly, a fault code is being emitted from the windows:-
“Side windows S21/9 down limit switch L”
“Side windows S21/8 down limit switch R”
But the confusion comes in that the car does not have down limit switches in the door – the limit switch is built into the motor. Which adds another dimension – according to Mercedes, the chassis number gives that the car should have limit switches in the door, but they definitely are not there. And at this point we are at a loss…
They have spoken with a main dealer to see if they had any ideas and, by co-incidence, they actually had a similar fault on the same model a few weeks ago. The issue was resolved on that one by replacing the Window Motors again with genuine Mercedes ones where the 2nd hand sourced ones (as with mine) were not working (overall symptoms were exactly the same and the same steps and replacements had been done as with mine – even to the point of saying it should have the limit switches in the door but didn’t).
I did ask if, when the testing is being done, it is being a down-up-down-up-down-up attempt (so the 3x movements all at the same time) or if there is a gap between them being done to simulate “real life” (so put the roof down, leave it a couple of hours, put it back up, leave it a couple of hours, put it down again, leave it, etc.) but I have been told that has been done already and, again, on the 3rd cycle it failed in the same way.
So, my questions / thoughts are...
- Why does it work fine for 2 passes and fail on the third, every time? Suggests a heating / shorting issue somewhere to me?
- Is replacing the Window Motors again going to solve the problem?
- How do we know it is not the roof control module (as I have been told the windows pass through that)?
- Has anyone else had similar problems in the past and know of any other options to solving?
Thanks in advance for any pointers / guidance.
Regards
Tim Watts
