See if this helps. On 72 cuda with new harness from year one, my left side front parking and side lights were dim.After 6 hours ,I found that there are two ground wires in one ring terminal that bolted to body by the radiator. The ring terminal was not crimped properly. The wire for the right side was making good connection ,However the wire literally touching it had poor connecton. I recrimped and the problem is gone. I even had the ring connection apart the day before to clean it and didnt see it, untill i tugged on the wire and lights got bright.