The first 12V power supply is not available前12V电源不可用

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 front 12V power supply harness is damaged or broken.检查前12V电源线束是否存在损坏、断裂等现象。 3. Check whether the front 12V power supply harness connector is empty or damaged.检查前12V电源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 → Go to step 2.是>>去步骤2。 No → Repair or replace the faulty wiring harness or connector.否>>维修或更换故障线束或接插件。
②Check fuse检查保险丝
	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 fuse IF01 in the electrical box on the instrument panel is normal.检查仪表板电器盒中保险丝IF01是否正常。 IF01：15A Are the test results normal?检查结果是否正常？ Yes → Go to step 3.是>>去步骤3。 No → Replace the fuse with the same specification.否>>更换相同规格保险丝。
③Check the front 12V power supply wiring harness检查前12V电源供电线束
	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. Disconnect the front 12V power harness connector IP44.断开前12V电源线束接插件IP44。 3. Connect the negative terminal of the 12V battery and the power status is "ON".连接蓄电池负极，电源状态“ON”。 4. Use a digital multimeter to measure the voltage between pin 2 of the IP44 and ground.用数字万用表测量IP44的2号针脚与接地之间的电压。 Standard voltage value: about 14V标准电压值：约14V Are the test results normal?检查结果是否正常？ Yes → Go to step 4.是>>去步骤4。 No → Repair or replace the front 12V power supply wiring harness.否>>维修或更换前12V电源供电线束。
④Check the front 12V power supply ground harness检查前12V电源接地线束
	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. Disconnect the front 12V power harness connector IP44.断开前12V电源线束接插件IP44。 3. Use a digital multimeter to measure the resistance between pin 1 of the IP44 and ground.用数字万用表测量IP44的1号针脚与接地之间的电阻。 Standard resistance value: <1标准电阻值：＜1 Ω Are the test results normal?检查结果是否正常？ Yes → Go to step 5.是>>去步骤5。 No → Repair or replace the front 12V power supply ground harness.否>>维修或更换前12V电源接地线束。
⑤Replace the front 12V power supply更换前12V电源
1. Replace the front 12V power supply and check whether the fault is eliminated.更换前12V电源，检查故障是否排除。 Are the test results normal?检查结果是否正常？ Yes → Fault resolved.是>>故障排除。 No → Find the cause from other fault symptoms.否>>从其他故障现象查找原因。