Fault phenomenon: a 2007 year Dongfeng Nissan Ji da car, the back door can not open failure. Inspection analysis: first check the car after the basic inspection, found the accident after the bumper, suspected that the rear part of the car has been extruded and can not open the back door, but continued inspection found that the mechanical switch inside the car can easily open the back door, this is not due to external force, because the car door lock by the car The body control module (BCM) control. Connect the fault detector into BCM to detect, no trouble code storage. After analyzing the data flow, it was found that the BCM did not receive the switch signal when the switch on the back door was pressed, and the rear door switch was checked. When examining the BCM related accessories, it was found that there was a trace of water in the right A column, and there was a pair of end connectors to BCM in the lower panel, and a connector check found that some of the connection terminals had been corroded. After continuing inspection, it was found that the fault was caused by the damage to the front front door sealing strip resulting from rain and caused the corrosion of BCM terminal connector terminal. Exclusive method: replace the right front door sealing strip and clean up the corroded BCM wiring harness connector terminal.