U041781 - TroubleshootingU041781-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
U041781	Received invalid message from EPB接收到EPB的无效报文	1. Communication failure1.通讯故障

Troubleshooting steps故障诊断步骤

①General 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 CAN communication harness is damaged or broken.检查CAN通讯线束是否存在损坏、断裂等现象。 3. Check the CAN communication harness connector for loose connections or damage.检查CAN通讯线束接插件是否存在虚接、损坏等现象。 Are the test results normal?检查结果是否正常？ Yes是 Go to step 2.去步骤2。 No否 Repair or replace the CAN communication harness or connector.维修或更换CAN通讯线束或接插件。

②Check CAN communication waveform检查CAN通讯波形

1. Power status "OFF".电源状态“OFF”。 2. Connect the oscilloscope.连接示波器。 3. Power status "ON".电源状态“ON”。 4. Use an oscilloscope to measure the waveforms of CAN-H and CAN-L.用示波器测量CAN-H和CAN-L的波形。 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 Check the CAN communication harness; if normal, go to step 3.检查CAN通讯线束；若正常，去步骤3。

③Check the electronic parking control unit检查电子驻车控制单元

1. Check whether the electronic parking control unit is normal.检查电子驻车控制单元是否正常。 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 Repair electronic parking control unit.维修电子驻车控制单元。

④Replace vehicle controller更换整车控制器

1. Replace the vehicle controller with a new one and check whether the fault code and symptoms are eliminated.更换新的整车控制器，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 vehicle controller, you need to use a diagnostic tool to recalibrate the vehicle controller.更换整车控制器后，需用诊断仪对整车控制器重新标定。