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1994 Cougar XR7 DOHC/5-Speed
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I may have found a solution!

I am reading Ford headlight switch diagrams, and apparently there is a circuit 484 (O/BK) which is hot when the ignition is on but off when the switch is turned to Parking or Headlights On.

This circuit is used to illuminate the radio LCD during the daytime.

Could I use this circuit to power my DRLs?
What year is your wiring diagram/EVTM for? The radio display isn’t a backlit LCD but a VFD display, it uses the illumination circuit(LG) as a signal to dim the brightness of the display internally when the lights come on. I don’t believe this 484 O/BK exists, but if your using a Ford EVTM tell me the numerical section to look in and I’ll check again.

I think you’ll need a relay one way or another, find a wire that’s on with ignition and run that to 30, with the light end coming off 87a(normally closed) and then for the coil energize use the parking light circuit to power that so when the switch is turned to park/headlight the relay will open the circuit and shut off the DRLs

You don’t need a DRL module. The only purpose of those is when you are using the actual headlight bulbs as a DRL and the module runs the high beams with a pulsed signal to make it less intense. With LEDs in the park position of the housing you definitely don’t need that
 

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1994 Cougar XR7 DOHC/5-Speed
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Honestly it would be cleaner to use a relay(preferably 2), there are numerous and way easier to access hot-in-run wires you can tap into to power the lights, and the parking lights obviously as a depowering trigger for the switching relay. You could avoid running any wires through the cabin and the hot in run circuits you can find under the hood are mostly beefier wires than most of the small gauge wires you’d be grabbing from inside the dash(of which I feel adding a relay and a separate fuse is necessary insurance)
 

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1994 Cougar XR7 DOHC/5-Speed
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For example?

I just figured interior would be good so the relay isn't exposed to the elements.

Speaking of which, could you show me a good example of a relay (link)?
Autozone today was less than helpful. I told the lady I was looking for a relay for such and such purpose. She asked the usual year, make and model. And I said no, it's not like that... We didn't get anywhere.
Off the top of my head the red ignition power circuit that powers up the fuel injectors, coils, and active sensors like the MAF, that’s hot in run. There are a bunch of other ones that are switched through the CCRM.

Relays are generic, no need to ask at the counter, you can find them in the aisles of a parts store along with weatherproof connectors for them, they’d look like this



The main thing to look for is one with 5 pins, with fifth being the normally closed 87a, 4 pin types won’t work for this purpose.

Most relays conveniently have the diagram molded into the sides like this, the way you’d wire it would be to run the hot-in-run wire you tapped into to 30, the wire(s) to the light sockets to 87a, the parking light wire to 85, 86 to ground, and leave 87 open
 

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1994 Cougar XR7 DOHC/5-Speed
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@XR7-4.6 , ok, I'm liking this idea more and more...

One thing I don't understand: why would a 4-pin relay not work, yet I'm leaving 87 open (so I'm only using 4 out of 5 pins)?
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

Also, would there be any harm in using the low-beam lead as a trigger instead of the parking lead?
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.

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.)
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.

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.
 

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1994 Cougar XR7 DOHC/5-Speed
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@XR7-4.6 , thank you so much for all your help. Before you chimed in, I was actually ready to just settle for making these lights supplemental turn signals - better than nothing.

But now I'm definitely liking the idea of using a relay. The only thing that I haven't figured out yet is where to pull the ignition power from. I really don't want to touch any powertrain or emissions components. I was thinking of doing a fuse tap; for example, the fuse for the rear defroster should be hot with ignition ON only. Unfortunately the fuse box is extremely tight.
The red wire for engine accessories wouldn’t necessarily be my first choice but there are others, the origin of that is from the CCRM which gets switched ignition power from the underhood power distribution box, I can’t exactly remember the color off the top of my head(it’s either yellow or red/green), which I’ll look up later but that one would be ideal. It’s fused, it’s under the hood and the wire is larger gauge.
 

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1994 Cougar XR7 DOHC/5-Speed
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Am I correct in believing that if you have leds in the brake lights your cruise control wont work? Because there is not enough of a current draw to detect through the brake on/off switch? Also, if that is correct, wouldn't it also affect the torque converter unlocking when you tap the brake?
I may be wrong.
It only affects cruise, the brake on/off switch sends 12v to the PCM the brakes are applied and that’s all it cares about, it isn’t impedance monitoring like cruise for some reason does
 
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