So I've been frustrated lately with the Ambient Light Sensor's understanding of how it thinks things should look vs how they actually look, lol.
I believe its function and my frequent North <-> South commute are not getting along well as a few minutes of shadows triggers the dimming of the DIC, MyLink and interior controls and then the remaining light that peaks through the trees, buildings, A-pillar, etc. on the way to work and back is often not steady enough to trigger the system that there is enough light to switch back to full bright. I'm often finding that the A-Pillar is shadowing my sensor and causing me to go or stay dim when it's perfectly bright out.
Some have found that their sensors were bad but I'm pretty confident that mine is working just fine as testing showed that the sensor would switch back and forth in just about 20 seconds when covered or uncovered in direct light.
Here's where I note that I take no responsibility for you screwing up your truck. If you choose to follow this guide you do so at your own responsibility.
I looked in the Electrical Upfitter manual and the Ambient Light Sensor (B10B) is shown to have 2 circuits that seem to control the brightness and how frequently it should be switching back and forth:
PIN 4 a yellow/violet wire the "Twilight Sentinel Delay Signal"
PIN 5 a white/blue wire the "Ambient Light Sensor Signal"
I thought that adding a switch to PIN 4 the, Twilight Sentinel Delay Signal, would hopefully remove any trigger that would dim the interior brightness...unfortunately this seems to have no effect on the brightness level but somehow must act as a averaging when you cross frequently between bright and shaded areas to know if there is more bright or shade and whether it should switch or not. - Not enjoying its current programming logic, obviously, lol
So I tried PIN 5 the Ambient Light Sensor Signal wire itself. Good news is that if there is no signal on this circuit the dash stays at full bright always. So I wired a switch into this circuit and viola I can now override the dim on demand. With the switch (circuit) closed it operates normally, dims when dark or shaded and if you want to override the dim just open the switch and in about 1-2 seconds youre back to full bright.
I tested with the headlights on and off and there is no change nor are there any errors or alerts from manually opening the circuit.
Here's where you learn from me ripping my entire dash apart today. You don't need to fumble around trying to monkey the sensor out of the dash like I did. The sensor wires are available right behind the radio face plate so you can splice in there as long as you have enough room to work.
This is a pic of the sensor itself and it harness. You can see the PIN 5 white/blue wire I removed from the harness in testing.
This pic unfortunately turned out worse than I was expecting
but this is the section of the Ambient Light Sensor wiring harness that is right behind the radio faceplate. You cant tell from the crappy pic but it's the small left most section in that splits off the bunch and routes back into the dash toward the front of the truck to the sensor.
Since I had the dash apart I pulled the entire harness out as it was easier to work. Here is the wiring with the sheathing pealed back for access. You can see the while/blue wire. I cut this and wired in a PIAA light switch I had laying around. I plan to add a better switch once I decide on where I want to permanently place it.
And that's pretty much it. Button up your dash and you can now override your brightness when the auto dimming isn't "mathing" right, lol
Here's a video in operation (you will need to click it to watch).
The video starts out on full bright with the sensor in the light and the circuit closed (everything working OEM) you can see the MyLink is full bright, DIC behavior is the same as the MyLink, I just couldn't get it in the shot.
At about 5 seconds into the video I cover the sensor, it takes about 20 seconds to switch to dim to night brightness (ignore the flickering it's just the camera nothing in the truck is flickering). Once on dim I open the switch and in about 1-2 seconds I go back to full bright with the sensor still covered. Click the switch again and 1-2 seconds back to dim and then one last open.
Hope y'all enjoy this as much as I'm gonna