U120088 - TroubleshootingU120088-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
U120088	CAN bus failureCAN总线故障	1. BUSOFF occurs on the first CAN channel. Possible reasons include short circuit between CAN_H and CAN_L, short circuit between CAN_H and ground, short circuit between CAN_L and power supply, or excessive bus disturbance.1.第一路CAN发生BUSOFF，可能原因有CAN_H与 CAN_L短路、CAN_H与地短路、CAN_L与电源短路或总线扰动过大等

Troubleshooting steps故障诊断步骤

①Power 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 2.去步骤2。

②Check your surroundings检查周围环境

1. Check the surrounding environment for the presence of magnetic fields.检查周围环境是否存在磁场。 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 Drive away from the current situation.驶离当前所处环境。

③Check wiring harness and connectors检查线束及接插件

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 PCAN communication harness is damaged or broken.检查PCAN通讯线束是否存在损坏、断裂等现象。 3. Check the PCAN communication harness connector for loose connections or damage.检查PCAN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 4.去步骤4。 No否 Repair or replace faulty wiring harness or connector.维修或更换故障线束或接插件。

④Check PCAN communication waveform检查PCAN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 PCAN-H and PCAN-L.用示波器测量PCAN-H和PCAN-L的波形。 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 Check the PCAN communication harness; if normal, go to step 5.检查PCAN通讯线束；若正常，去步骤5。

⑤Check other related systems on the PCAN communication bus检查PCAN通讯总线上其他相关系统

1. Check whether other related systems on the PCAN bus are normal.检查PCAN总线上其他相关系统是否正常。 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 Repair related faulty systems.维修相关故障系统。

⑥Replacing 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。