Volunteer

14WhiteZ71: This reply assumes you have a 2014 GMC Sierra SLE with the projector style lams and no LED DRL's as factory options. {If the SLT model you seem to own is in any way different than the SLE then I cannot vouch for this info. Early on in this thread is a post describing the differences in headlight equipment between Chevy and GMC and amongst the various trim options. There are a lot of variations.} I think your best bet is to jiggle or unplug and then replug the relay box which is more or less at the convergence of the four wires which go to the battery and then to the headlamps. The center of the "H" so to speak. If it is loose or is vibrating upon feeling it you have a bad connection which may improve upon re-seating it. It can only plug in one way so no worries about plugging it back in incorrectly. It does not look like a removable part upon casual inspection but it actually is. I don't know if you can buy the relay individually without the wires but the cost is small enough that replacing the whole wiring relay is no big deal even if you now have two sets of wires and only one relay plug is not too wastefull. Beyond that, it appears you have already actually replaced the whole system. Also I would go ahead and use both capacitors even though only one is possibly not necessary. If it is not needed but is in use, you always have a ready replacement available if the passenger "necessary" side fails. You just swap them left to right and away you go from your roadside repair. Volunteer

This may sound stupid but this is what happened to me (several weeks ago). Is bought two complete sets of bulbs, ballasts and relays from DDM. One was in 55 watt and the other in 35 watt. BTW these two rigs are identical except for the capacitors. I installed a 35 watt set of capacitors and the other necessary parts and I could find no light output. I was certain I had done the whole thing correctly even though I was the first one on the forum to have noted a change in the relay harness from DDM as compared to Moto's original description. I pulled the whole outfit off, re-installed, same thing no lights. I kept changing things and worked at this for hours until the sun went down at which point I realized what a moron I had been. I later came to believe the whole thing had been working from the get go but I didn't realize this until sundown when I could actually see the lights were working even when set up as I had originally done. I had been ducking my head down in bright daylight looking for light output and seeing none because I did not duck low enough to be in direct line of sight to the center of the projector lenses. When seen from a slight angle from above in bright light, the output is not apparent. You have to actually place your head low enough in front of the light assembles to properly appreciate whether they are working. I reaffirmed my suspicion by changing out parts and bulbs and ballasts and every time they worked when set up as I originally had done no matter what combination of parts I used. I have seen a number of frustrated posts by those with "no light output" problems and I hesitated to write this post as I don't want to insult anyone's intelligence especially when they are at the point of throwing the whole idea of installing HID's out the window. Take my experience for what it is worth. YMMV of course but at least be sure you are finding you have no lights when you expect to see them (in a dark environment) and not just in broad daylight.