Lighted emblem plugs into headlight assembly harness (instructions for that assembly are, unplug the connector on the headlight assembly, insert the lighted emblem harness in the middle between the plug that used to go to the headlight assembly and the headlight, then plug into the headlight and the emblem).
Would guess this is a safe spot to tap power, but there are multiple wires on that harness (some for the parking lights, some for the running lights, and some for the headlights). The challenge is which of those is the full 12V, and which is dimmed for the dimming DRL's, etc.
If you are working in the fender well, it may be ok to grab power from the side marker...that one is easy to test, should be 2 wires, PWR and GND. Unplug it, put a voltmeter on the two pins, turn on the headlights, should be 12V between those 2.
Depending on how much lighting you are adding, you may be OK there; but without the schematics...and seeing what all is on the circuit, and knowing the power requirements of what you are adding, its hard to know if the existing wiring can accommodate the added load, and if the existing fuse is enough.
I can certainly help you read schematics...if you can get them.
Edit: Just read the OP's OP again...he specifically mentions DRL.
That is probably the one I would be most concerned tapping, since it clearly has a bright and dim function...This could be implemented in a couple different ways.
-It could be a PWM (pulse width modulated) signal from the BCM, where the brightness is controlled by switching the 12V on and off more or less rapidly so that the average power is less than would be if it was constant on (one way to know might be to video the DRL's and watch them back, if they flicker on the camera, we know this is how it is implemented). If you measure it w/ a voltmeter, you will just get the average voltage, you would need an oscilloscope to see the true waveform.
-Or, it could be just a solid ON w/ varying voltages to control the dimming.
-Or the "smarts" for brightness could be designed into the headlight assembly, and a separate signal delivered to the assembly by the BCM to select Bright/Dim/Off is provided.
-Or something else than the above...
This is where having the circuit to look at helps a ton.
GM Upfitter site has the electrical schematics for the headlights...see here -->
https://www.gmupfitter.com/wp-conte...XL_Electrical_Body_Builder_SM_U_2021OCT13.pdf
Looks like there are a bunch of "modules" in the circuit, BCM, Lighting Control Module, and the Headlamp Assembly.
Further, on page 2-15, I see evidence of PWM controls coming out of K219 Module (see the little square wave symbol on the switches indicated as F6UA, F9UA, F30UA..these are likely not actually switches, but circuits/transistors switching the output to deliver the desired brightness/power).
Last, my read is that all of the signals going from the Lighting Control Module to the Headlight Assembly from F6UA, F9UA, and F30UA are control signals, and the headlights/DRL's are powrered from the Battery Voltage input coming in on Pin 2 of the Headlight Assembly.
Those are my quick look thoughts, will have to read the description of how things work a little more, later in the document...but that will have to be a later project..no time today.
