When test ACM module, in accordance with the instructions required to make the group D 1000V. As a result, to make the 20V about pressure could not beat up, preliminary judgement is the connection box, replace the connection box or not, check the line there is no any problem, later examination revealed a GDU is not good, the door polar put in the problem of position A21 GDU pressure hit but, gate line change to other GDU pressure test can be played, production of replacement position A21 GDU again after pressure test, pressure normal.