Auto-Dim tap in spot

I have a 2020 Tundra limited and recently got platinum mirror and have all the wires installed and tapped into there systems.

I am having a hell of a time find where I should tap in the auto dim feature. Can any one shine some light on this one for me?

 

The side view mirror auto darkening is controlled by the rear view mirror. My truck is a bit older and I did this a long time ago. If memory serves, I tapped into an segment of the factory harness that ran down the driver side A-pillar from the rear view mirror for the back-up camera then had to run wires from there to each side view mirror.

 

Yea I am looking into it just can’t find the right pair of wires... the first time I tapped into it, it would just turn the lights on. Which then just autodimmed the mirror ( like it completed the circuit)

 

Try to get the rear view mirror to darken by covering the square sensor on the back side (facing windshield) and shining a light at a similar sensor on the interior facing side (the side facing the driver) to get the rear view mirror to darken. There has to be power to the mirror for this to occur. I think this produces a small voltage on the wire(s) that trigger the the side mirrors. I can't recall how I determined the correct wire, I may have already determined that, or just connected them experimentally and watched the side view mirrors. It should happen within 20 seconds or so.

 

In my signature is a link to the Wiring Diagrams thread for the Tundra. Download the 2018-2021 circuit diagrams and you’ll find the wiring info in the EC Mirror diagram.

Grab the introductory information document as well if you need help understanding how to read the diagrams.

 

So I found it in the diagrams and found the connector in the driver side pillar. It’s grey/black wire pin 13/4. I tapped into it and then did the test. No voltage occurred during the test... I then looked at the back of the mirror and noticed the pin locations were 3/4 were flipped. Do I have to swap those to make this work?

 

The voltage was speculative. It may actually complete the circuit by creating a path to ground. I oftentimes forget that's how Toyota frequently does things. I know that it's not always the best way, but sometimes you need to do a little trial/error; that's how I recall eventually sorting mine out.

 

So I finally took the time to figure this one out… it’s quite funny… basically the tap in spots were correct.. the T-Tap connector I used didn’t strip the wire when I placed them on. Put the right ones on gauge wise and it works! Multimeter for the win!