Red Light by Outside Mirror? Trans?

2000 Xcab, Prerunner V6, 4X2.

What's the red light on the door panel by the mirror for? I had the panel off to install speakers and there's wires running from the light to the mirror.

How do I tell which auto trans I have to buy a replacement filter? It's a 3 speed with OD.

Thanks.

 

If I had to guess all the filters would be the same.

I think its the A340E and F if its 4wd

 

its the A340E as for the light sounds like it might be part of an alarm ?

 

Added pics of lights.

 

Heated mirrors?

 

I doubt it, no switch to turn it on.
Just two wires running from the light to the mirror.

 

some kind of blind spot system?

http://www.tadibrothers.com/Catalog/BlindSpotSystem/Blind-Spot-System

 

Do you know where the axle code is indicated on your truck? There's a transmission code right next to it. It's all on a tag with seemingly meaningless strings of numbers/letters on it on the door jamb.

 

Thanks.