Auto Headlights

[iceman121314]

Hi guys,

Can anyone of you tell me were I can find the lightsensor of the automatic headlight system on a Avensis T25?

An electricwiring diagram would be very nice ;)

[Phoenix999]

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[jamesholden]

Not sure if this is what you really want to know, but it's one of the black blobs at the top of the dash just behind the windscreen, you can find out which one by having them set to auto and covering it up, it'll think it's dark and the lights will come on.

[downtime]

Not sure if this is what you really want to know, but it's one of the black blobs at the top of the dash just behind the windscreen, you can find out which one by having them set to auto and covering it up, it'll think it's dark and the lights will come on.

Nope. It's integrated to the rain sensor. It's both the rain and light sensor. You can see the sensor on the top part of the windscreen looked from outside.

The one on the dash is the sunlight sensor for AUTO A/C.

[jamesholden]

Not sure if this is what you really want to know, but it's one of the black blobs at the top of the dash just behind the windscreen, you can find out which one by having them set to auto and covering it up, it'll think it's dark and the lights will come on.

Nope. It's integrated to the rain sensor. It's both the rain and light sensor. You can see the sensor on the top part of the windscreen looked from outside.

The one on the dash is the sunlight sensor for AUTO A/C.

Sorry! Must be different on my Camry then, i've got two on the dash, one for the lights, and one for the climate, and the rain sensor is independent.

[iceman121314]

Not sure if this is what you really want to know, but it's one of the black blobs at the top of the dash just behind the windscreen, you can find out which one by having them set to auto and covering it up, it'll think it's dark and the lights will come on.

Nope. It's integrated to the rain sensor. It's both the rain and light sensor. You can see the sensor on the top part of the windscreen looked from outside.

The one on the dash is the sunlight sensor for AUTO A/C.

Thanks downtime, that's all I needed to know:)

My rainsensor is broken.

Explains why my auto wipers are not working too.

[downtime]

Not sure if this is what you really want to know, but it's one of the black blobs at the top of the dash just behind the windscreen, you can find out which one by having them set to auto and covering it up, it'll think it's dark and the lights will come on.

Nope. It's integrated to the rain sensor. It's both the rain and light sensor. You can see the sensor on the top part of the windscreen looked from outside.

The one on the dash is the sunlight sensor for AUTO A/C.

Sorry! Must be different on my Camry then, i've got two on the dash, one for the lights, and one for the climate, and the rain sensor is independent.

Ok, it's different then. Avensis only has one on the dash and thats for the A/C.

The rain sensor is basically just a light sensor so that's why all the car manufacturers use that also for the auto lights. Cheaper that to implement another light sensor just for auto lights :)

Thanks downtime, that's all I needed to know:)

My rainsensor is broken.

Explains why my auto wipers are not working too.

You're welcome.

Have you checked that the fuse is ok? If I remember correctly there should be a fuse for the rain sensor or it was combined with something. Anyway, the rain sensor usually doesn't break very easily. And if it does, not very cheap to replace as you need to replace the whole windscreen. It's integrated to that.

[Jamesbelfast]

If the rain sensor was just a light sensor how come it can operate both day and night???:)

[downtime]

If the rain sensor was just a light sensor how come it can operate both day and night???:)

The rain sensor just deciphers the how the light is reflected back to the sensor. There are small leds on the sensor that emit light to the windscreen and a few photoresistors which "read" the light reflected back to them. The rain drops or any drops on the windscreen obstruct this reflection and based on that it deciphers if the windscreen needs wiping or not. You can adjust the sensivity of the sensor with the wiper stalk usually.

So they actually use the light sensor part of the rain sensor...<--- hmmm lot of sensors there :). It's cheaper and more efficient to do than a separate light sensor. And in these modern CAN -bus cars it's really easy to do.

That's how it is done in VAG cars and I'm pretty sure it's the same in any modern car.

[t-spiritpete]

If the rain sensor was just a light sensor how come it can operate both day and night??? :)

The rain sensor just deciphers the how the light is reflected back to the sensor. There are small leds on the sensor that emit light to the windscreen and a few photoresistors which "read" the light reflected back to them. The rain drops or any drops on the windscreen obstruct this reflection and based on that it deciphers if the windscreen needs wiping or not. You can adjust the sensivity of the sensor with the wiper stalk usually.

So they actually use the light sensor part of the rain sensor...<--- hmmm lot of sensors there :) . It's cheaper and more efficient to do than a separate light sensor. And in these modern CAN -bus cars it's really easy to do.

That's how it is done in VAG cars and I'm pretty sure it's the same in any modern car.

Makes sense to me, sorry about the pun oops!

What is the sensor for that is stuck to the windscreen behind the rear view mirror for then?

Pete.

[jamesholden]

If the rain sensor was just a light sensor how come it can operate both day and night??? :)

The rain sensor just deciphers the how the light is reflected back to the sensor. There are small leds on the sensor that emit light to the windscreen and a few photoresistors which "read" the light reflected back to them. The rain drops or any drops on the windscreen obstruct this reflection and based on that it deciphers if the windscreen needs wiping or not. You can adjust the sensivity of the sensor with the wiper stalk usually.

So they actually use the light sensor part of the rain sensor...<--- hmmm lot of sensors there :) . It's cheaper and more efficient to do than a separate light sensor. And in these modern CAN -bus cars it's really easy to do.

That's how it is done in VAG cars and I'm pretty sure it's the same in any modern car.

Makes sense to me, sorry about the pun oops!

What is the sensor for that is stuck to the windscreen behind the rear view mirror for then?

Pete.

That is the rain sensor module in question.

[t-spiritpete]

If the rain sensor was just a light sensor how come it can operate both day and night??? :)

The rain sensor just deciphers the how the light is reflected back to the sensor. There are small leds on the sensor that emit light to the windscreen and a few photoresistors which "read" the light reflected back to them. The rain drops or any drops on the windscreen obstruct this reflection and based on that it deciphers if the windscreen needs wiping or not. You can adjust the sensivity of the sensor with the wiper stalk usually.

So they actually use the light sensor part of the rain sensor...<--- hmmm lot of sensors there :) . It's cheaper and more efficient to do than a separate light sensor. And in these modern CAN -bus cars it's really easy to do.

That's how it is done in VAG cars and I'm pretty sure it's the same in any modern car.

Makes sense to me, sorry about the pun oops!

What is the sensor for that is stuck to the windscreen behind the rear view mirror for then?

Pete.

That is the rain sensor module in question.

Hi James, so the one stuck to the top of the screen behind the rear view mirror is the rain sensor and the small black dome at the bottom right of the screen/dashboard is the light sensor, that's the way I think anyway, I don't think there is anything built into the windscreen glass.

Pete.

[Jamesbelfast]

If the rain sensor was just a light sensor how come it can operate both day and night???:)

The rain sensor just deciphers the how the light is reflected back to the sensor. There are small leds on the sensor that emit light to the windscreen and a few photoresistors which "read" the light reflected back to them. The rain drops or any drops on the windscreen obstruct this reflection and based on that it deciphers if the windscreen needs wiping or not. You can adjust the sensivity of the sensor with the wiper stalk usually.

So they actually use the light sensor part of the rain sensor...<--- hmmm lot of sensors there :). It's cheaper and more efficient to do than a separate light sensor. And in these modern CAN -bus cars it's really easy to do.

That's how it is done in VAG cars and I'm pretty sure it's the same in any modern car.

A very good explanation apart from one aspect - the sensor measures the refractive index of the of the glass and when water hits the screen the index changes.

[downtime]

If the rain sensor was just a light sensor how come it can operate both day and night??? :)

The rain sensor just deciphers the how the light is reflected back to the sensor. There are small leds on the sensor that emit light to the windscreen and a few photoresistors which "read" the light reflected back to them. The rain drops or any drops on the windscreen obstruct this reflection and based on that it deciphers if the windscreen needs wiping or not. You can adjust the sensivity of the sensor with the wiper stalk usually.

So they actually use the light sensor part of the rain sensor...<--- hmmm lot of sensors there :) . It's cheaper and more efficient to do than a separate light sensor. And in these modern CAN -bus cars it's really easy to do.

That's how it is done in VAG cars and I'm pretty sure it's the same in any modern car.

Makes sense to me, sorry about the pun oops!

What is the sensor for that is stuck to the windscreen behind the rear view mirror for then?

Pete.

That is the rain sensor module in question.

Hi James, so the one stuck to the top of the screen behind the rear view mirror is the rain sensor and the small black dome at the bottom right of the screen/dashboard is the light sensor, that's the way I think anyway, I don't think there is anything built into the windscreen glass.

Pete.

It's NOT built into the glass, IT'S BONDED to the glass. You cannot change the rain sensor without changing the complete windscreen.

And the light sensor is still part of the rain sensor. On Camry it's different but Avensis, Verso etc. they all have the light sensor as part of the rain sensor. The small dome on the dash is a sunlight sensor for the A/C. I think this is explained in the user manual.

the sensor measures the refractive index of the of the glass and when water hits the screen the index changes.

True. Sorry, English not my native language so I didn't explain it good enough. Thanks for pointing this out.