Where is the auto rain sensor

[Avgasandy]

Hi can anyone tell me where to look,
I recently changed my front wiper blades to the new style wiper blades and what a difference these have made, the only downside is my auto rain sensor does not seem to operate correctly anymore. When you select first position on wiper stalk the wiper sweeps the windscreen twice and then thats it it stops no matter how hard it rains, i might get 1 more sweep after a while but by that time i have usually changed to 2nd position on the stalk to regain visability.
The car is the mk 2 hdi
Anyone any sugestions, looked at my old wiper blades and they look like standard old blades.
Thanks for looking

[DaiRees]

Morning ,

The rain sensor is at the top of the windcreen in the middle, housed in the bit that your rear veiw mirror is attached to. I very much doubt that your wiper blades are causing this fault though, I've fitted aero blades to mine about a month or so back and the auto function is still working fine. Put the old ones back on and go for a spin in the rain just to see if it's the blades causing it. You haven't had your windcsreen changed recently have you?

[mjb]

You'll see a little rectangle at the top of the screen where the rearview mirror's mounted. That's the rain sensor. Changing blades won't affect its operation in the slightest. You've probably just got a lump of mud/tar/etc stuck over it or something... Have you had a new 'screen recently?

[Welly]

At the bottom of my screen, in the blacked out glass bit there is a row of 000000's right under each wiper blade. I don't know what they do but they must be there for some reason, changing the blade arms might have changed this bit?

Also I wonder if the new blades aren't sweeping the sensor i.e. they are not long enough. The passenger one sweeps the sensor clear each time.

[DaiRees]

Also I wonder if the new blades aren't sweeping the sensor i.e. they are not long enough. The passenger one sweeps the sensor clear each time.

If that was the case wouldn't they be constantly on rather than not working?...... Unless.... there's some feedback jiggerypokery whereby the sensor needs to tell the ECU that it's been swiped, and if it doesn't get the signal that it's been swiped it shut's the system down.

[Welly]

The sensor would have to count the 'sweeps' IMO. In other words "how much water has passed over the sensor since the last wipe" i.e. rainfall intensity?????

[DaiRees]

My guess is that it emits a light source and measures the intensity of the reflection. More water on the screen = more scatter of the light so less reflection, so turn on the wipers. If that's the case it wouldn't necessarily need to count wiper sweeps.

[Welly]

Wikipedia says..........

The most common rain sensor implementation is based on the prinicple of total internal reflection: an infrared light is beamed at a 45-degree angle into the windshield from the inside near the lower edge — if the glass is wet, less light makes it back to the sensor, and the wipers turn on.

Bejesus! I've turned into 'V6exec'

[DaiRees]

Bejesus, I got something right!!!!

[Welly]

This would also explain why it looks like one of the orange lights is out on the sensor when you look at it.

It only shines from one side at 45 degrees.

[bargainbro]

I've fitted aero blades to mine

Say what? Are those available for 406, too? I gave up the search some time ago...




.

[steve_earwig]

I'll just settle for finding anything that fits...

The other day, while I was waiting for my girlfriend (a common occurance) I was dripping water on the sensor from the wet roof to get them to wipe. Drip, wipe. Drip, wipe...

I was thinking maybe they weren't long enough but I think someone covered that one. It's unlikely to be a coincidence though.

[mjb]

I've fitted aero blades to mine

Say what? Are those available for 406, too? I gave up the search some time ago...

Not the 'proper' ones I don't think, but I've done over 40k on some knock-offs I got off ebay which are still working much better than normal blades!

[DaiRees]

I've fitted aero blades to mine

Say what? Are those available for 406, too? I gave up the search some time ago...




.

Indeed, had to go for the Valeo retrofit ones in the end, I must say they are very good. Yes I know they're stupidly expensive and just a gimmick but they really do work better that my previous set of "normal" Bosch blades did, even when they were new. Very smooth and quiet. They really are unobtrusive too, although I keep meaning to... errrrmm.... modify the arms to allow them to sit lower too.

Got them off this bloke on ebay.

I really wanted the Bosch Aerotwin Retrofit ones but they still don't do them for the 406.

[Avgasandy]

Hi I put my old wiper blades back on today went for a spin still same problem get the initial 2 sweeps of the screen then nothing.
Both passenger side wiper blades normal and aero sweep the sensor, I have not had a new windscreen fitted both sensors light up orange so dont know what the problem could be.
Its just annoying having to have the wipers on all the time in drizzel.
Any other suggestions for me to try?