This paper presents a novel test generation technique for defective power TSV induced path delay faults in 3D IC. This paper provides a simple close-form analysis to show that, in a regular 3D power grid model, open defects in power TSV do not induce serious IR drop. However, leakage defects in power TSV should be tested, even though the number of power TSV is large. This paper proposes a test generation flow to detect path delay faults induced by defective power TSV. The proposed technique is demonstrated on an 18-tier, 7 x 7 multi-core 3D IC model. In the experiment of b18 and b19 benchmark circuits, all detectable path delay faults induced by power TSV can be tested by around hundred test patterns. This technique requires no extra DfT hardware overhead.