When you turn the low beam headlamps on and they don't light up... do fuses 3 (lf low beam) and 4 (rf low beam) have power? These being in the under hood fuse block. Use the test light you're gonna purchase (non self powered test light) to check. Put the test light ground to batt negative or other suitable ground and touch the tip of the test light to the back of the fuse blades and see if the test light comes on.
I wouldn't suspect a ground problem cos the lf low and high share a ground and the rf low and high share a ground. If the high beams work, the grounds work.
