1994 Cougar XR7 DOHC/5-Speed
Because 87a is normally closed, where 87 is normally open. The way you’ll wire this is the ignition power will pass straight through it to the DRLs without the relay coil being energized at all. Only when you flip on the lights will the coil energize and switch the lead from 87a to 87, which will then shut off the DRLs as desired
No harm, it would work the same, but that would mean the DRLs will not turn off with parking lights and will come back on with high beam.Also, would there be any harm in using the low-beam lead as a trigger instead of the parking lead?
For me it’s far less about the power draw than it is the shorting hazard, when you set up a typical relay circuit you’re taking a “fresh” source of 12v ideally straight from the battery to power whatever it is you want powered, and if it shorts from an accident(which being for lights is at the most vulnerable place) there’s no thing to stop sparks and a potential fire from starting, so adding a fuse is necessary, always placed towards the power source.And finally, you mentioned adding a fuse earlier. Where would I do that? Consider that we're talking about two LEDs with a total output of 3.4 Watts; isn't that minuscule?
(Sorry, I'm a total newbie at this.)
As for weatherproofing relays are pretty weatherproofed as is, the terminals are more exposed than a weathertight connector but once together they don’t really need much protection, just glob on some dielectric grease and you’re good to go really.