So I installed a Ford DRL module on a 2005 Excursion today. It has HID headlights so my options were to wire it in to turn on the fog lights or park lights.
With the fog lights on in DRL mode there is a buzzing noise coming from the fuse pannel. Pull the switch to turn on the fog lights and the noise goes away.
When wired to the park lights there is no noise.

It seems as though with the reduced voltage in the DRL mode somthing is buzzing.

Any ideas as to what it might be.
The park lights are protected by a 10 amp fuse.

 

You call this a "Ford DRL module". Does this mean it was made for your vehicle, and is plug and play with instructions? How do they say how to install it?

 

Ford DRL module is a universal module from Ford that you could use to install DRL on any vehicle.

This module turns on the DRL lights after a 15 second delay at about 75% power. They will turn off as soon as any of the normal lights are turned on.




Red-Constant
Red/GN-ignition
Black-ground
Purple-brake switch
Brown-Park lights
Red/BK-low beams (fog lights in my case due to HID leadlights)

 

See if you have a foglamp relay. See if it's what is buzzing.

 

Found out the fog lamp relay is non serviceable inside the central junction box.
I'm going to have to find out a way to rewire it.