Adding LED Running Lights

[Markday3]

2020 3500HD LTZ DMAX.  There is a perfect seam along the bottom of the cab for adding LED running lights.  I was told by service writer that I cannot wire into the park light wire in the pigtail or 7 pin outlet or it will cause a problem with the control module that runs the 7 pin trailer outlet.  I want to add 5 LED running lights on each side of the cab.  Does anyone know where I can wire them into to have them work automatically with the park lights?

[Coolade]

Purchase the Putco wiring harness that pigtails a 4pin harness out of your taillights and hard wire into that 4pin connector and you will be golden.

[EJCarter]

I have seen threads on this form and the Duramax Forum where numerous people have installed manufactured LED strip running lights in this location or made their own by purchasing a quality weather-proof roll of LED lights and cut to the desired length. 

Tapping these ultra low draw LED to the location of your choice should not create any issues (under bed rail or inside tool boxes for example). Some have run the wires into the cab through the rubber grommets just on the back side of that body seam and tapped them into the dome light wire (to illuminate the running board with the key fob, door open, and fade off), others have tapped them into the back of the trailer plug (to be used as running lights), or purchase the adapter as stated from Coolade above and tie into your tail lights...it just depends how you want them illuminated. I saw where a guy drilled small 3/4" holes in the running board supporting brackets and installed flush mount round LEDs in each bracket to illuminate the running boards when the doors where open...pretty clean. 

A couple years ago, I installed Rigid Back Up Lights in the bumper steps and tapped into the back up light wire just above behind each tail light. I have never had any issues by adding these. In fact, the dealer where I purchased my truck saw what I did and now will custom install these through their parts dept. I believe your service writer might just not know the big picture...