P1AFC00 - P1AFC00 On-board Charger High Voltage Interlock Fault

Detailed Fault Definition

DTC P1AFC00 (On-Board Charger High Voltage Interlock Fault) plays a critical safety monitoring role in the vehicle's entire high-voltage electrical architecture. This fault code is directly associated with the status of the high-voltage interlock loop between the On-Board Charger (OBC) and the Integrated Intelligent Drive Controller. In electrical safety logic, the high-voltage interlock system provides real-time feedback on the connection integrity of the motor and charging system through the closed and open states of physical connectors, ensuring high voltage current flows only along safe paths. When the onboard charger acts as an energy conversion core, if the voltage signal at its input end cannot be maintained within normal logic thresholds, or if the Integrated Intelligent Drive Controller fails to correctly interpret that voltage pulse signal, the system will determine the interlock loop to have failed, triggering the P1AFC00 fault code record. This definition clarifies the dependency relationship between the control unit, feedback loop, and physical connection point.

Common Fault Symptoms

When the system detects a high-voltage interlock abnormality and writes DTC P1AFC00, the vehicle's Human-Machine Interface (HMI) will provide clear warning information to the driver. Specific perceptible driving experience and instrument feedback include:

• Instrument Warning: The central screen or indicator light area of the vehicle dashboard may display "Please check connector" text prompt, informing the driver that the charging interface may have physical looseness.
• Limited Charging Function: The On-Board Charger may interrupt the charging process, unable to establish a normal energy transmission path, causing the external AC power source to fail in replenishing energy for the battery pack.
• System Status Light On: High-voltage system fault indicator light or battery management related warning lights may turn on, indicating that the vehicle's entire high-voltage interlock network has integrity risks.

Core Fault Cause Analysis

According to existing raw data analysis, the trigger causes for this fault code can be classified into potential problems in three dimensions: hardware connection status, wiring physical properties, and controller logic calculation:

• Connectors and Hardware Components: The AC charging port connector of the Integrated Intelligent Drive Controller is not fully engaged. This is the most common external factor, causing the high-voltage interlock loop to disconnect physically, so that the onboard charger cannot detect a closed signal.
• Controller Hardware Itself: Internal hardware damage or sensor failure occurs in the Integrated Intelligent Drive Controller, causing it to be unable to correctly collect the voltage status of the on-board charger, thus generating false fault reports.
• Wiring Connection Integrity: Although the main cause is connectors not being connected properly, the harness of the high-voltage interlock loop itself may exist open or loose contact phenomena, causing the control unit received signals not to meet preset logic conditions.

Technical Monitoring and Trigger Logic

The onboard charger's high-voltage interlock function is based on real-time voltage signal sampling for dynamic determination, with specific operating conditions for fault determination as follows:

• System Operating Condition Premise: The fault only takes effect when the vehicle is powered on (Power On) and is in a specific discharge process flow (Discharge Process Flow). In this state, if the onboard charger voltage is less than the prescribed threshold value, the system will immediately generate a fault code.
• Monitoring Target Parameters: Primarily monitor the real-time input/output voltage level of the on-board charger and its change rate. The control unit will compare current sampled voltage with preset normal ranges.
• Trigger Threshold Logic: When the collected onboard charger voltage signal is long below the prescribed threshold (Voltage < Prescribed Threshold), and the duration exceeds the system set determination window, the Integrated Intelligent Drive Controller will output fault code P1AFC00. This process does not rely on specific absolute voltage values but on comparison results of relative logic thresholds.