Where is the auto light sensor?

[azibux1]

Hi all,

As above, NOT HBA ... Simple auto lights with day / night time

Past few days I've been noticing my lights on during broad daylight. Thought it was possibly my dashcam blocking the sensor (the one on the mirror itself), it is very close but not blocking it exactly I'd say... But I removed the dashcam, drove a further 5 minutes (roughly) and the lights were still on instead of DRLs

Switch on dash is in the auto position

There is one sensor on the mirror itself and one at the bottom of the mirror 'base' if that makes sense, I have HBA so not sure which is which

Even when I find the sensor I'm not sure why it isn't working haha

Any advice please?

Thanks!

 

[Rob2k68]

The large square at the front of your interior rear view mirror is the camera for HBA, the smaller squares less than 1cm are at the front and back and this is to control the dimming function of the mirror itself - if the rear facing sensor has a higher light input compared to the front it will dim.

To the best of my knowledge the auto lights sensor is built into the rain sensor on the windshield which is why they are often offered together (auto lights and wipers) as an option. Happy to be corrected on this.

Edit : BTW lights coming on during bright conditions isn't uncommon and shouldn't give cause for concern.

 

[gamegenie]

 

[Gordo77]

To the best of my knowledge the auto lights sensor is built into the rain sensor on the windshield which is why they are often offered together (auto lights and wipers) as an option. Happy to be corrected on this.

Edit : BTW lights coming on during bright conditions isn't uncommon and shouldn't give cause for concern.

Yes, my standing too about the light sensor. I think it "looks" at the brightness of the sky, which is why they sometimes come on in what we would consider bright conditions.

 

[azibux1]

Ahhh right cool then! That should be fine then

Yeah the one I was referring to being close to blocking with the dashcam is the one @gamegenie has photographed

I didn't even spot one on the front of the mirror haha. Clever how that works though

 

[DJAlix]

• Rain, Light and Humidity Sensor (RLFS / RLHS) = Controls Auto Lights, Auto Wipers and Aircon only.
• High Beam Assist Sensor = Controls HBA only.
• Dimming Mirror Sensor = Controls the mirror dimming function only and does not communicate with the car in any way. Cars previous to the MQB platform used to use this sensor as a Light Sensor for Auto Lights in addition to mirror dimming.

There is also a Sunlight sensor, if you have automatic climate control, center of the dash and works with Aircon only. Coming Home / Leaving Home Lights are triggered via the RLFS / RLHS.

If your lights are coming on earlier than normal then the reason is ambient / weather based and not blockage, unless you have something stuck to the outside of your windscreen or it's very dirty. The only other reason as to why your lights might switch on would be if you have configured your RLFS / RLHS to activate "Rain Lights" which would switch your lights on during any rain thats more than just a light shower. BMW's have this by default which is why you see them all driving around with their lights on during the rain.

Audi Auto Lights are good at coming on during what we would consider to be conditions which are not dark enough. The RLFS / RLHS is configurable but only to make it more sensitive and thus make the lights come on even sooner

 

[azibux1]

Thanks for the very detailed response @DJAlix!!!

Just what I was looking for and very informative

Simply out of interest, do you know in what way the RLFS/RLHS affects the air con??

 

[DJAlix]

Thanks for the very detailed response @DJAlix!!!

Just what I was looking for and very informative

Simply out of interest, do you know in what way the RLFS/RLHS affects the air con??

It monitors the ambient humidity / dew point and sends the data to the climate control unit in order to try and prevent condensation I believe.

 

[azibux1]

Clever stuff!