U019987 - TroubleshootingU019987-故障诊断

Fault code description故障码说明

DTC故障码(DTC)	Fault code description故障码描述	Possible cause of failure可能故障原因
U019987	There is a communication failure with FLDCM and messages are lost.与FLDCM通讯存在故障，报文丢失	1. Lost communication with FLDCM1.与FLDCM丢失通信

Troubleshooting steps故障诊断步骤

①Power-on inspection (take the left rear blind spot monitoring main sensor as an example for inspection)上电检查(以左后盲区监测主传感器为例进行检查)

1. Repower the vehicle, use the diagnostic tool to read and clear the fault codes, and check whether the fault codes and symptoms are eliminated.车辆重新上电，使用诊断仪读取并清除故障码，检查故障码及症状是否排除。 Are the test results normal?检查结果是否正常？ Yes是 Fault resolved.故障排除。 No否 Go to step 2.去步骤2。

②General inspection一般检查

1. Power state is "OFF", disconnect the negative terminal of the 12V battery.电源状态“OFF”，断开蓄电池负极。 2. Check whether the BCAN communication harness is damaged or broken.检查BCAN通讯线束是否存在损坏、断裂等现象。 3. Check whether the ACANFD communication harness is damaged or broken.检查ACANFD通讯线束是否存在损坏、断裂等现象。 4. Check the wiring harness connector for damage, loose connection, etc.检查线束接插件是否存在损坏、虚接等现象。 Are the test results normal?检查结果是否正常？ Yes是 Go to step 3.去步骤3。 No否 Repair or replace faulty wiring harness or connector.维修或更换故障线束或接插件。

③Check for electromagnetic interference检查电磁干扰

1. Check for the presence of magnetic fields around the vehicle.检查车辆周围是否存在磁场。 Are the test results normal?检查结果是否正常？ Yes是 Go to step 4.去步骤4。 No否 Move the vehicle away from the current environment.将车辆驶离当前环境。

④Check left front door control module fault code检查左前门控制模块故障码

1. Use a diagnostic tool to read the fault code of the left front door control module and check whether there is a fault in the left front door control module.使用诊断仪读取左前门控制模块故障码，检查左前门控制模块是否存在故障。 Are the test results normal?检查结果是否正常？ Yes是 Go to step 5.去步骤5。 No否 Troubleshoot according to the fault code.根据故障码排除故障。

⑤Check the gateway controller fault code检查网关控制器故障码

1. Use a diagnostic tool to read the fault code of the gateway controller and check whether there is a fault in the gateway controller.使用诊断仪读取网关控制器故障码，检查网关控制器是否存在故障。 Are the test results normal?检查结果是否正常？ Yes是 Go to step 6.去步骤6。 No否 Troubleshoot according to the fault code.根据故障码排除故障。

⑥Replace the left rear blind spot monitoring main sensor更换左后盲区监测主传感器

1. Replace with a new left rear blind spot monitoring main sensor and check whether the fault code and symptoms are eliminated.更换新的左后盲区监测主传感器，检查故障码及症状是否排除。 Are the test results normal?检查结果是否正常？ Yes是 Fault resolved.故障排除。 No否 Look for causes from other symptoms.从其他症状查找原因。   Caution:注意： ♦  After replacing the main sensor for monitoring the left rear blind spot, you need to use a diagnostic instrument to recalibrate the main sensor for monitoring the left rear blind spot.更换左后盲区监测主传感器后，需用诊断仪对左后盲区监测主传感器重新标定。