Ambient Light Sensor wiring help needed 2005 Yukon XL

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05YukonXL

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[SOLVED SEE BELOW] I am attempting to disable the ambient light sensor in my 2005 Yukon XL SLT to prevent the highlights automatically activating the circuit when dark outside (to protect aftermarket HID ballasts during ignition). You know, using a 1.5k resistor... Can anyone help identify the wires at the sensor or BCM?

Easy enough to splice resistor under dash or at sensor, if I confidently knew which wires to splice :) I can't seem to find wiring diagrams online for my year/make/model.

Looking at a number of threads and comparing those to my truck, my BMC looks different (or I suck at identifying BCM bits). This BCM has 5 ports on the 'front' and one in the back/bottom. None of the identified wires/ports seem to match up. ('purple' plug in hand plugs into back/bottom position)
image1.JPG


I pulled the dash for a look at the sensor plug and wires. This version of sensor supports both lighting and HVAC (3709-07164055) and has four wires (see photo: black, light green, blue/black strip, off white) Again, easy enough to splice resistor here :)

FullSizeRender.jpg

Sensor type image:
Screen Shot 2019-03-24 at 11.50.28 AM.png Screen Shot 2019-03-24 at 11.50.33 AM.png

Thanks in advance for any insights and help!
 
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Doubeleive

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it's probably less hassle and headache to just wire up a toggle switch to the low beam headlight wires and put it under the dash. I have ran HID's since they have pretty much been around,how long they last is really random some I have had last a decade or more others less never worried about "protecting there use" since there so cheap it doesn't really matter. I have found that voltage is what plays a major factor in HID's I recommend using relays and direct thick gauge wiring to the battery & grounds and just use the headlight positive as a trigger and pretty much completely avoid using the factory wiring.
 

Doubeleive

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also just a side note I believe the ambient light sensor is also known as a "sun-load" sensor and effects the HVAC system as well. but I could be wrong
 
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05YukonXL

05YukonXL

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Yes it is a combo Sunload Sensor + Ambient Light Sensor Signal which is why there are more than just two wires I/O. Power switch toggle would be too easy? I took a gamble that the black wire (ground) and white was the signal back BCM for the light sensor, turns out a good guess on my part.
 
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05YukonXL

05YukonXL

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Never mind all the BCM garbage above, I kind of solved this. Let me explain....

Since I already had the dash off to get a better look at the SENSOR, I went ahead and tapped the black (ground) and white (signal to BCM) wires that lead to it .

I could of just spliced in the resistor in but I added a toggle switch for greater control.

While not as 'easy' as splicing wires UNDER this works - taking the dash off isn't all the difficult anyway. (Plenty of youtube videos to help you.) Plus, I didn't figure out what wires under the dash were the right ones anyway.

Sensor:
IMG_3136.JPG Spliced in a wires (aka tap)IMG_3153.JPG
Not pictured is RESISTOR..
Then here is the toggle switch:
Screen Shot 2019-03-24 at 10.00.51 PM.png Screen Shot 2019-03-24 at 10.00.58 PM.png
Best part, it works. I hope this helps someone else!

Finally, i think this is correct for the leads to/from the sensor:

Blue/BK - Driver Sunload Sensor Signal
Green - Passenger Sunload Sensor Signal
Black - Ground
White - Ambient Light Sensor Signal
 

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