For the inspection of automotive wire harness elongation, it should be tested according to the elongation and the relevant national standards. If the customer has special requirements, it must be strictly controlled according to its requirements. The specific step is to open the switch of the elongation tester, and then carefully observe whether the sensor on the left is in the original position and whether the reading displayed on the instrument is zero or not if the sensor clip on the left is not in the original position. If the reading displayed on the instrument does not return to zero, then immediately press the recovery button and the zero button. Then gently open the sensor clip, place one of the copper wires to be inspected in the sensor clip, then press the sensor clip, then straighten the copper wire and place the other end in the other sensor clip. Lower the induction clip, clamp the copper wire, and press the test button. Finally, when the sensor clip pulls the copper wire off and stops moving, observe the reading shown on the instrument. The above reading is the elongation of the copper wire to be tested.