Insignia 2014 diesel eco. The wipers often will not start, except by demanding wash, when they always work. After driving for a while the wipers start working, either using the intermittent selection or either of normal or fast settings, but changing a setting can cause the wipers to stop again and they may then start again after a while. The problem exists on all 3 setting positions, except for the wash-pull. Evidently power does arrive at the stalk switch. Rear wiper works OK. It is puzzling how a bad connection could cause this. I have been testing them while stopped - engine off. Is it necessary to be moving? Is the Computer involved with wiper control? When they work, the speeds are as expected, so the motor seems OK
I succeeded in fixing the problem.
The wiper stalk switch is removed by squeezing the plastic strips top and bottom and pulling it out of the housing. Unfortunately the release for the connector is out of sight underneath the switch so a bit difficult. The release for this connector is on the inner side facing the control column. There are two screws holding one side of the switch together, but this gives access only to the sprung plunger that holds the switch in the three positions. Taking it apart is unnecessary unless re-greasing is wanted.
The other side of the switch can be removed by releasing the plastic lugs. This then allows the disconnection of a small connector and removal of the PEC after removing the screw. The main contact slider can then be removed, noting its orientation. In my case 2 of the contact prongs were corroded. The copper strips had pairs of marks where the slider stopped, which was worrying as it looked as though there might be holes. After cleaning and re-assembly the switch works properly. There is another contact slider, presumably for the rear wiper.
I have more pictures of the repair, but they exceed the allowance.