Rav5 has arrived .

Got a new question for those in the know.

The auto wipers on the this rav4 are not functioning , at least I don't think they are.

When I turn them on, there is the initial 1 x wipe, then nothing.

If I rotate the stalk to increase the sensitivety, I again get the 1 x wipe, but them nothing again,

regardless of how heavy it is raining.

Is there anything obvious I'm missing , or is it time to phone the garage ?

If you've turned the sensitivity right up and still no wiping, apart from the initial on sensitivity adjustment, then yep probably a sensor problem.

Previous Toyota wiper system (and possibly this one), would revert to a fixed intermittent wipe, if the rain sensor was not connected (What Kev is getting at).

My own hypothesis (nothing done on my part to confirm it) is that some of the rain sensors get de-sensitised by the infra-red content in sunlight. I feel the systems work more consistently with rain at night. (Maybe try it).

Actually, a quick look @ a simple typical IR detector datasheet e.g:

www.farnell.com/datasheets/2049183.pdf

page 3, figure 6, shows an increase (non-linear) in detection threshold with ambient light, which would go along a little with how I feel the system behaves.

The rain sensor works on the principal of internal reflection on the boundary between the glass and a water droplet. infra red is fired @ the windscreen. A rain drop on the screen means less of the IR gets reflected back to the IR detector in the rain sensor.

I don't know exactly the details, but normally with systems you need some way of "subtracting" or removing the effects of any "background" (in this case light) levels/noise. I wouldn't be surprised if the IR transmission from the sensor is modulated with a pattern to help with this, but it's maybe not totally impossible if the thing reaches a point where the ambient light completely saturates the detector preventing any drop detection.

Yeah, OK, it tends not to be bright sunlight when it's raining, but........

Other systems use the lane departure warning (LDW)/traffic sign camera to do image recognition on the spots. It's technology overkill in a way, but cheaper than an additional sensor for the vehicle manufacturer, if the camera is already fitted anyway. Toyota on this model still have a separate LDW camera and rain sensor.