C5 x7 wipers only intermittent in rain and other bizarre issue

[rdodger]

Hi, I hope someone can shed light on this extraordinary problem.
During heavy rain with automatic sensing on the wipers stayed in intermittent (very scary) and stayed so even when changed to manual. Once rain stopped manual worked fine.
1st thing I’ve done is disconnect the sensor behind the rear view mirror yet somehow the wipers respond the same when it rains overriding the manual set. I then found the sensor fuse and removed that and it happens again?.
Is there somehow that the wipers respond to friction on the screen or is there another sensor?. I will take the car to a specialist eventually but I hope someone can point me in the right direction to just have manual wiping working in the meantime.
Cheers!.

[GiveMeABreak]

The sensor is dual function. It is used for the lights as well as the wiping. It would seem that your auto function is not working and that it has fallen back to the standard intermittent wipe.

It may be that the sensor is faulty, but it may be something else like the switch control module under the steering wheel. So before swapping parts, it needs diagnosing with Diagbox to determine where the fault lies as it could be several issues. If you've had the windscreen replaced that can cause the sensor to malfunction or reduce effectiveness if the gel pad has become clouded or opaque.

[rdodger]

Thanks for the information though how the wipers know it’s raining when I’ve disconnected the sensor is quite bemusing. There is a local sparks and sensors company who will look at it once I’ve given up on self diagnosis, they have a 3 week waiting list, looks like a career choice for a young mechanic…..

[GiveMeABreak]

Because it is not using the sensor.

The modes are:
AUTO = Automatic Mode
0 = Park
I = Intermittent (which is proportional to the speed of the vehicle)
1 = Normal
2 = Fast

If there is a fault with the automatic mode, then the default backup mode is to operate in Intermittent Mode (I).

So you may have a fault with the sensor itself or the wiring possibly. Do the lights come on automatically at night when the lighting stalk is in the Auto position?