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	EPB signal is invalidEPB信号无效	1.EPB signal is invalid1.EPB信号无效

Troubleshooting steps故障诊断步骤

①General inspection一般检查

1. Check whether the ACANFD communication harness and PCAN communication harness are damaged or broken.检查ACANFD通讯线束和PCAN通讯线束是否存在损坏、断裂等现象。 2. Check whether the ACANFD communication harness and PCAN communication harness connectors are damaged or disconnected.检查ACANFD通讯线束和PCAN通讯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 2.去步骤2。 No否 Repair or replace the faulty communication harness.维修或更换故障通讯线束。

②Power on check上电检查

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 3.去步骤3。

③Check for electromagnetic interference检查电磁干扰

1. Check for sources of magnetic fields around the vehicle.检查车辆周围是否存在磁场源。 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 its current environment.使车辆驶离当前环境。

④Check electronic parking control unit fault code检查电子驻车控制单元故障码

1. Use a diagnostic tool to read the fault code of the electronic parking control unit and check whether there is a fault in the electronic parking control unit.使用诊断仪读取电子驻车控制单元故障码，检查电子驻车控制单元是否存在故障。 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 the electronic parking control unit according to the fault code.根据故障码排除电子驻车控制单元故障。

⑤Replacing the integrated brake control unit更换集成式制动控制单元

1. Replace with a new integrated brake control unit and check whether the fault code and symptoms are eliminated.更换新的集成式制动控制单元，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 integrated brake control unit, you need to use a diagnostic tool to recalibrate the integrated brake control unit.更换集成式制动控制单元后，需用诊断仪对集成式制动控制单元重新标定。 ♦  After replacing the integrated brake control unit, the brake line bleeding operation is required.更换集成式制动控制单元后，需进行制动管路排气操作。