Today I worked on simplifying ways to attach lights or switch them easily. I added these bulk strips to make adding and moving what lights go to which switch easier. I'm not always satisfied what lights I'm combining to which switch. My truck only has 4 switches as the idiot that ordered it...
I can tell you the cel is not limited to power train. There's a ton of other things that trigger cel. Including but not limited to electrical issues un related to power train. Such as a window control module that applies voltage to window control when the vehicle is off.
This was my task to do took a bit. Light bar from Amazon lights too. I put red led square lights facing rear tied to the brake light and the center light is tied to the backup lights.