yoderrm

Thanks again for your help! I think we're on the right track. Let me digest your diagram while I wait for the relay to arrive. I'll need to convert it to "mechanical speak" before I go any further, lol. If all goes well, I'll post a how-to with pics. If it doesn't go well... I'll be glad I have the Lamby 100% BCM replacement guarantee! Hahahaha

Yeah, I tested in drive... although the first time I didn't and thought I'd blown something, lol. When the truck is in drive, here's what happens with the 10/22 diode on place: In daylight, the DRLs come on. Fog lights do NOT come on automatically. At night, auto headlights come on. Fog lights come on automatically, and cannot be turned off unless all lights are turned off by the knob. Day or night, if I turn knob to parking lights or headlights, the fog lights come on automatically. They remain on if I turn on the highbeams, and cannot be turned off unless all lights are turned off.

Thanks, Lamby! One potential problem: on the 16-18 silverados, even though the DRLs and parking lights are the same lights, they appear to have different signals. I have the 10/22 jumper currently, and the fogs do not come on with the DRLs during the day. Once the DRLs dim and become "parking lights" (either by auto headlights coming on, or turning knob) the fog lights come on. That's why I was thinking I would need another diode from x4-7. Does that make sense? Hopefully I'm understanding correctly.

I noticed the wire for the low beams was heavier guage. I never got further than finding the bcm diagram and identifying the wires before it got dark outside. For some reason, I couldn't trick the ambient light sensor with a flash light, so I was never able to test the daytime running light signal. My soldering and wiring skills are fine, I'm just incredibly ignorant at electronic circuits, haha. I really appreciate your help! Just so I'm clear on what you're saying: Upon startup, foglights will automatically come on, no matter what. At any time, pressing the fog light switch turns them off. Pressing again turns them back on. Turning the truck off, then back on, will reset the circuit and turn the lights back on. Correct?

Yeah, I understand I'm probably in the minority (as usual) for wanting them on in the day. For me, it's half for safety and half aesthetics. Not a deal breaker, but my preference. I appreciate you looking into a circuit. If I get off work at a decent time tomorrow I might try the diodes and see what it does.

No, I don't have the auto dimming/brights. If you do a reverse ignition feed, are you able to turn off the fogs? I would want to turn them off at the boat ramp in the mornings, but leave the parking lights on.

Sorry to dig up an old thread... I currently have the 10/22 diode jump on my 2018 Silverado, as posted by @Spurshot. It'll work for now, but isn't exactly what I'm looking for long-term. Ideally, I want the fogs to "auto" on, regardless of day or night, low beam or high beam (10/22 diode only turns them on at night). However, I want to be able to turn on my parking lights at the boat ramp without turning on my fogs (10/22 diode doesn't allow this). This seems similar to what the OP was hoping for. The original @Lamby66 circuit gets close, but wouldn't come on during the day with DRLs, if I'm understanding it right. Only thing I can think to do is to use three diodes: one from high beams to fogs (X5-18 to X5-10), one from low beams to fogs (X4-1 to X5-10), and one from DRLs to fogs (X4-7 to X5-10). This should keep the fogs on during daytime with DRLs, and at night with both low beams or high beams. Then, at the boat ramp, I can turn my knob from auto to parking lights, which shouldn't trigger the fogs unless I press the fog switch. Sorry if this was covered in the foglights to high beams thread... I tried to go through all of it. Has anyone tried this on the 16-18 Silverados? Not sure if it will work since DRLs and parking lights are technically the same light, albeit different signals. Or does anyone have any other ideas? I've got a few more diodes laying around, and hope to try it this week if I get some time.