Hi everyone, newbie here. What about a voltage drop test on the ground side of any circuit needing testing. Connect one lead of the VM to the ground side (point of ground) of the circuit being tested and the other lead to the post of the negative side of the battery. Select your lowest voltage scale on the VM. 0vdc is a perfect reading and ground is not your problem. Any reading higher then that indicates issues. Keep in mind this does not cover a vehicle moving (twisting & bending) down the road. You would need to leave the VM hookup for a road test.
Now on the lights, jeeps are not the softest in rides, but on-off, off-on, on-off, heats and cools the bulbs many times. This is hard on them. Thermo shock can ruin any light bulb (filament).
I like electron flow (- to +).