What are the issues with abnormal noise in car wiring harnesses

During the road test evaluation of a certain vehicle model on twisted roads, concave manhole covers, convex manhole covers, cobblestone roads, and gravel roads, it was found that there was a slight knocking sound on the left side of the back door (near the driver's side), while the noise disappeared on non bumpy roads. As shown in Figure 3.

1）The cause of the problem. Firstly, the fault is reproduced through real vehicle simulation, that is, when the back door is open, use your hand to tap the sheet metal at the rear end, and the range of abnormal sound is initially locked near the left tail light (Figure 4). Secondly, the elimination method was used to remove interference components such as the interior panel and tail lights in sequence, and the abnormal noise was ultimately caused by knocking on the main part of the tailgate wiring harness wrapped in the base and the sheet metal.

2） Solution measures. Based on the contact between the trunk of the back door harness and the internal reinforcement plate of the back door sheet metal on bumpy road sections, the contact area of the trunk of the back door harness is optimized to be wrapped with external sponge tape. Through multiple verifications on bumpy road sections, the issue of abnormal knocking noise has been resolved.