Anotherrustbucket

I hey guys, I'm having this exact problem with my hi 60. i have found that when the car is running with no accessories on it runs great. As soon as I put my headlights on and/or fan that my voltage drops and EDIC motor starts working with the fuel control relay clicking away in the kick panel. Now I figured out that when I disconnect the fuel control relay that I can use all accessories and have no issue with Low voltage or the EDIC motor cutting off the fuel supply. my alternator and battery have just been replaced and voltage is perfect. Thoughts please on how to overcome this issue or test that the fuel control relay is the issue??