Originally I sent a pic that didn't show up the fog lights operate off the same relay etc. You had stated that the one side worked which in the pic both operate off the same relay so it could be a wiring issue like shorting out or partially broken between LH and RH sides. So make sure to check that. The smart box problem I thought was limited to expeditions but not really sure. It is 2003-06 that have that problem and it's normally the fuel pump circuit that screws up, not the lights. So check the wiring in the pic as it may have a problem there it is the same color on both sides. Also check the grounds as they are separate and could be the problem for one light.