I've had two sets of Morimoto on the NNBS that worked flawlessly. My third set I put on my 15 Yukon (I just sold actually), had the same issue. Pulled the kit. In the process, one of the connectors on the black/red cable snapped off and lost the O ring to the HID bulb. TRS is sending a new connector and a new O Ring free of charge. I had troubleshooted the kit to death, testing each bulb and ballast on the "working" side. The only thing I never tested was the dual relay cubes and harness. I ordered a second one for $30, and still same issue. So I Was at a loss as I tested every component and STILL had the issue. By the time I asked them to return the second relay to get my $30 back, I Was out of their 45 day return window so now i'm stuck with two of them. I plan on putting this kit in my new 2010 Tahoe LTZ I just acquired so hopefully I have better luck on this truck..