I like having my daytime running lamps on during the day, but in the morning/evening hours, I like to run with my fogs on. First I did the fog light mod so the fogs are on when the running lights are on. But the DRL’s would be on with the fogs. So I started digging through the wiring diagrams and found a solution: the DRL module has an input for automatics when they are in Park. When this input is grounded, the DRL’s turn off. This input is connected to a trigger wire for the running lights (or any other ground trigger).

Note: This will probably won’t work with an automatic transmission.

Car: 2002-2003 WRX. 2004 should be the same as well.

Tools required:
Philips screwdriver
10mm socket and extension
Razor blade
Electrical tape
Soldering iron

Materials:
About 2 feet of insulated wire (18ga is fine)
1 small female spade crimp connector

If you want your fog lights to come on with the parklights, then do this mod first: http://www.scoobymods.com/forums/showthread.php?s=&threadid=1022

Next, remove the glove box to expose the DRL module. Once its out of the way, the DRL module is on the right side, behind the black and blue relays. The screw for the module is behind the black relay.

Once the DRL module is unscrewed, unplug it. Looking at the back of the connector, pass the insulated wire through the hole shown.

Now crimp the female spade connector on the portion of the wire sticking out the front of the plug. You should remove the plastic portion from the spade connector before crimping it to the wire.

Plug the spade connector into the corresponding pin on the DRL module. This pin is used for "park" on automatics, but is unused on manuals.

Carefully slide the connector over the spade and make sure it latches. If the spade connector doesn't want to fit, then crimp it at different points to make it smaller so it will fit into the connector.

Now put the DRL module back where it came from and reinstall the screw.

Next, you need to find a wire that is ground triggered when the park lights are on. Fortunately, the ECU has a wire that does just that. You can use any other ground triggered wire, but this one was the closest.

Pull back the carpet and remove the ECU kick plate. There are 4 bolts holding it on, 3 that you can see, and 1 is up top behind the blower motor. Unplug the uppermost ECU plug. In my pics, the plugs all run into the UTEC first, but the plugs are in the same order on the factory ECU.

Take off the tape and pull back the black covering. You’ll need to tap into wire 17 on the plug, which is black with a white stripe (see the pic). Take the razor blade and strip back some of the insulation. Wrap your wire around this spot, solder, and tape. Button everything back up in reverse order and you're done! The DRL’s will now turn off when you turn the running lights on!