当线束的内部出现断线故障时，由于外部绝缘皮的包裹，使断线的确切位置不易确定。用数字万用表可以将这一难题轻松搞定。具体方法：

 

1）把有断点的线束（电线电缆）一端接在220V市电的火线上，另一端悬空。

 

2）将数字万用表拔至AC2V挡，从线束（电线电缆）的火线接入端开始，用一只手捏住黑表笔的笔尖，另一只手将红表笔沿导线的绝缘皮慢慢移动，此时显示屏显示的电压值大约为0.445V（DT890D型表所测）左右。

 

3）移动红表笔，当红表笔移动到某处时，显示屏显示的电压突然下降到0.0几伏（大约是原来电压的十分之一）。

 

4）从该位置向前（火线接入端）的大约 15cm处即是线束（电线电缆）断点所在。

When the inner part of the wire harness is broken, the exact position of the broken wire is not easy to be determined because of the wrapping of the outer insulating skin. This problem can be easily solved with a digital multimeter. Specific Methods: 1) have a break point of the wire harness (wire and cable) one end connected to the 220V city fire line, the other end hanging. 2) pull the DMM to the AC2V block, starting from the wire access end of the wire harness (wire cable) , hold the NIB of the black stylus with one hand, and slowly move the red stylus along the insulation of the wire with the other hand. The voltage on the display is about 0.445V (as measured by the DT890D) . 3) move the Red Stylus. When the stylus moves somewhere, the voltage on the display suddenly drops to a little over 0.0 volts (about a tenth of the original voltage) . 4) approximately 15 cm from this point forward (fire access) is the point at which the harness (wire and cable) breaks.