Red LED on Dash

[Fisher99]

I've searched my manual but can't find a description of the little red LED in the middle of the dash. Sits on the same plane as the HVAC fan controls. To the right of the fan controls and to the left of the passenger vent control.

 

[GoldiE46]

this one, right?

I am also wondering the same

 

[Fisher99]

Yes, that's the one. I've looked in my paper manual and also the online manual, and while the LED shows in the pics of the dash, there's no explanation of what it's for.

 

[EvanstonI3]

Ask it to Open the Pod Bay Doors and see if you get a response.

 

[Pahaska]

It is not a LED. It is the cabin temperature sensor.

 

[GoldiE46]

It is not a LED. It is the cabin temperature sensor.

interesting. it seems that you are correct. thanks pahaska

 

[jadnashuanh]

It could be a light intensity (photo sensor). During the day, place your finger over it and see if the display brightness changes. If they get dimmer, it's not a temperature sensor.

 

[eNate]

It could be a light intensity (photo sensor). During the day, place your finger over it and see if the display brightness changes. If they get dimmer, it's not a temperature sensor.

The photosensor for the insturment & screen dimming is on the bottom center of the speedometer display, in line with the lower row of illuminated warning icons.

This one in question looks more like an IR receiver. Vehicle cabin temp sensors usually have a grated opening ; I've never seen one with a lens.

 

[Fisher99]

I just checked and it's not the sensor for diming the dash lights. As Nate says, that sensor is on the main instrument cluster screen. The more I look at this the more it looks like just a little plastic cap that BMW decided to put on the dash just to make people wonder what it is. And if so, it is certainly working!

Seriously though, it must have a function. If I had a BMW dealer close by I'd stop and ask them. If It is indeed an IR receiver (and it does look like it could be), I can't imagine what for.

 

[Anonymous]

I asked my Dealer about this some time ago. According to their Service Manager, (as several people already posted) it is the cabin temperature sensor - he said it is an IR (Infrared) sensor by design so that the cabin temp. readings cannot be thrown off by heat from the sun shining on the dash/sensor.

 

[Fisher99]

Interesting! Don't think I've ever seen an IR temp sensor in a car before. My wife's 535i xDrive doesn't have it. Thanks to PAHASKA and MKH for providing that clarification!

 

[Anonymous]

My wife's 535i xDrive doesn't have it.

The IR sensor is there. Looks like a small button below the left AC knob.

 

[Fisher99]

Not on my wife's 535i. In that location there is a small "grille" with holes to allow air temp sensing. The IR is probably something they started on a later year model than hers.

 

[eNate]

Don't think I've ever seen an IR temp sensor in a car before.

Same! But it looks like this is pretty common implementation with many of BMW's other models, and the sensor is called out in some of those cars' service manuals. Although I found reference to a back seat remote control (not for the i3)... anyone know about that?

If this is indeed a temp sensor that affects warm/cold air flow, it ought to be easy to test.

 

[Anonymous]

If this is indeed a temp sensor that affects warm/cold air flow, it ought to be easy to test.

Would be interesting. Since IR Temp guns don't measure air temp, they measure 'reflected' heat of the object they are pointed at - how do these IR sensors work exactly? Focused on a spot or wider area in the car?

For cars with the back seat 'entertainment' system and remote control for it - remember reading somewhere that the IR receiver for that was usually in the overhead console.

 

[Fisher99]

If this is indeed a temp sensor that affects warm/cold air flow, it ought to be easy to test.

Would be interesting. Since IR Temp guns don't measure air temp, they measure 'reflected' heat of the object they are pointed at - how do these IR sensors work exactly? Focused on a spot or wider area in the car?

For cars with the back seat 'entertainment' system and remote control for it - remember reading somewhere that the IR receiver for that was usually in the overhead console.

Now I know what that red dot on my forehead is when I'm driving my i3....

 

[websterize]

"Temperature sensor, center vent" or, to a 10-year-old passenger, a part of the front ejection seat/moonroof/Assist option, available on select I01 models. (Yes, she sits in the back seat.)

 

[Anonymous]

"Temperature sensor, center vent"

Yes. The goal of the system is to get the IR cabin temp reading and the center vent temp reading to match per the temp dialed in on the console thermostat knob. If cabin temp from the IR sensor is 50F and the center vent is pumping out 70F+ air, the heater will keep running until the cabin and vent readings equalize at the temp you have set - say 70F. If the vent sensor was the only one, and you set your control to 70F, minutes after you turned on the heat, the vent sensor would reach 70F, shut of the heat, and you'd still be sitting in a 50F+ car.

 

[eNate]

I played with this sensor some.

I don't think it's infrared.

It takes direct contact for a few minutes to effect a temperature change in the air coming out of the vents.

Plus, if you shine a flashlight at it, the sensor appears opaque. IR sensors, while often dark, require enough transparency for light to pass through.

I'm thinking the sensor is just a thermocouple in a heat-conductive covering, and we're just seeing the tip poking through the dash.

 

[Anonymous]

I'm thinking the sensor is just a thermocouple in a heat-conductive covering, and we're just seeing the tip poking through the dash.

That actually makes sense - an IR sensor has to be focused on a surface to read temp, and has a lens to focus the IR beam. neither of which seem to fit what we are seeing on the dash.