Hallo everybody,
I am from the Netherlands and I have a problem with the closing of the left doorwindow. My car is a Fiat Ducato 244 from dec 2002 (camper)
It doesn't close, when I switch the poles of the electrical circuit of the closing motor then it works properly.
So I think it is Module M135 witch causes the problem ?
Does anyone know where the Module precisley is mounted ?
Sorry for my poor english.
I hope you can help me !

Cor

On my 244 it is right behind the glove compartment. You have to remove it to reach the brown M135 box.

However I had once problems with the central locking and thought too it was the M135, but it turns out it wasn't ...

The M135 process a number of signals, so if the other still work (such as central locking, other doorwindow, etc.) it is quite unlikely, that the M135 is buggy, more likely the fault lies somewhere else...

In your case I would start checking for ground and short circuit on the cables which are connected to the motor. My guess is the isolation went off somewhere on the cables.
For instance if the fault only happens sometimes (e.g. after wet conditions) thats also a good sign for this.