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	P-CAN bus offlineP-CAN总线离线	1.P-CAN bus load is too high1.P-CAN总线负载过高
		2. There is an error frame on the P-CAN bus2.P-CAN总线上存在错误帧
		3. There is poor contact when connecting external devices, causing the bus to be temporarily closed.3.连接外部设备时有接触不良的情况，造成总线临时关闭

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。

③General 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 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。

⑥Replace gateway controller更换网关控制器

1. Replace with a new gateway controller and check whether the fault code and symptoms are eliminated.更换新的网关控制器，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 gateway controller, you need to use a diagnostic tool to recalibrate the gateway controller.更换网关控制器后，需用诊断仪对网关控制器重新标定。