Originally Posted by masol
Tail and brake lights share the ground so it is working, verify if 12 vdc is present, use the multimeter
Stock they all share the same ground. The bulb bases ground through the tail light housing, through the bolts, then the body.
There are 3 wires coming from the stock harness, reverse, parking lights (low intensity), and stop/turn signal (high intensity).
There are two bulbs in the housing. 1 is the reverse and the other is a dual filament/dual contact bulb that can output the two intensities.
If stop is working but not turn, it's a problem further up in the wiring and you can rule out a ground problem, since they are the same bulb.
OP, what EXACTLY isn't working. Stop lights, turn signal, or parking lights?