New to the 4th Gen

[WayneC]

I'm a previous 2nd Gen TDR member who let his membership lapse because most of the most talked about information had passed me by. Now, about three weeks ago, I bought a 2015 Ram 2500 SLT Mega Cab 4wd. Fantastic truck. I 'm replacing my 1998 Dodge 2500 24 Valve Cummins Automatic with 276,000 miles on it that I've owned for 17 years because it doesn't have the cojones to pull our 10k on travel trailer through any kind of mountains. On my 98, I cut the clutch safety switch wire and added a kill switch to that wire. Reading several posts on the TDR, I find that I can install a kill switch on my 2015 at the starter relay. Logic tells me to find and clip the ground wire, add a leg to both pieces on up to a hidden button that I would have to press in order to complete the ground and start my truck, similar to my '98. My question is, which one is the ground wire going under the power distribution center to the starter relay (what color)?