P1ADF00 Fault Technical Specification Document

Detailed Definition of Fault

P1ADF00 is a specific vehicle diagnostic trouble code (DTC), with its core logic describing the strong coupling relationship between the whole vehicle thermal management system and energy management strategy. In the architecture of new energy vehicles, the efficient operation of the power battery pack relies on the dynamic regulation of the cooling system, which is highly integrated into the HVAC system. This fault code indicates that when the vehicle control unit detects an abnormal state in the HVAC subsystem, it triggers a safety protection logic to temporarily prohibit executing "battery internal circulation" or related battery thermal management operations. This belongs to an active safety mechanism, aimed at preventing charging or high-power discharging of high energy density batteries under operating conditions with insufficient cooling capacity or instability, thereby ensuring overall vehicle operation safety and control stability.

Common Fault Symptoms

When the system determines and records the P1ADF00 fault code, drivers and the In-Vehicle Information System (IVI) usually experience the following feedback phenomena:

• Vehicle Function Restriction: The instrument panel displays battery-related warning information, indicating that the battery internal circulation mode cannot be entered due to thermal management faults.
• HVAC Operating Condition Anomaly: Failure of in-vehicle temperature regulation, blower motor stoppage or inability to start the compressor, accompanied by lighting up of the corresponding HVAC system fault lamp.
• Driving Experience Impact: If the vehicle is in a driving mode relying on the HVAC system for temperature control (such as certain extended-range or pure electric mode transition periods), power output restriction may occur or emergency operation mode may be entered.
• System Record Storage: The vehicle OBD system stores the fault status in memory, and requires clearing operations after maintenance to restore normal system logic judgment.

Core Fault Cause Analysis

According to the technical direction of original diagnostic data, the occurrence mechanism of this fault can be summarized as hardware or logic abnormalities in the following three dimensions:

1. Hardware Components (HVAC and Power Battery Pack)

   • HVAC System Failure: Refers to physical damage to components such as compressors, evaporators, condensers, or temperature sensors, resulting in heat exchange efficiency that does not meet the minimum requirements of the battery management system.
   • Power Battery Pack Failure: Involves abnormality of BMS communication within the battery module or unstable High Voltage Interlock Loop (HVIL) status. Although the main cause is triggered by an HVAC fault, fluctuations in the power battery state itself may also link to this logic judgment.

2. Wiring/Connectors (Physical Connection)

   • Harness or Connector Failure: Includes signal transmission line open circuit, short circuit between the controller and various actuators, as well as connector pin withdrawal, oxidation, or excessive contact resistance. This can cause control instructions to fail to reach HVAC components accurately, or feedback signals to interrupt.

3. Controller (Logic Operation)

   • Right Domain Controller Failure: When the vehicle adopts a distributed domain control architecture, the right domain controller is responsible for managing control unit functions for specific areas (such as right-side body and HVAC parts). If internal logic calculation errors occur or communication modules fail within it, it will incorrectly report HVAC system abnormal signals upwards, thereby triggering the generation of P1ADF00 fault code.

4. Power Supply (Protection Mechanism)

   • Fuse Failure: Refers to the main power supply path on which fuses for the HVAC system or related thermal management circuits burn out or degrade in performance, causing downstream equipment to fail to respond normally to control instructions due to lack of supply voltage.

Technical Monitoring and Trigger Logic

The system's determination process is based on high-precision real-time data stream monitoring and safety state machines, following the following technical trigger logic:

• Monitoring Targets

  • System focuses on monitoring HVAC actuator work status feedback signals (such as compressor speed, fan speed), battery temperature sensor data, and communication status frames between domain controllers.
  • Simultaneously monitors high-voltage loop power supply integrity and fuse continuity status to ensure thermal management components obtain stable electric power supply.

• Numerical Thresholds and Logic Conditions

  • Voltage Continuity Verification: The system checks whether the voltage drop on the power supply line meets the preset range (if $0V$ abnormality exists, open circuit is determined), ensuring no power protection circuit misoperation.
  • Communication Status Interpretation: CAN/LIN bus signals between right domain controller and HVAC controller must maintain real-time interaction; once communication timeout or parity error occurs, it is deemed "HVAC System Fault".
  • Operating Condition Dependency Monitoring: This fault is activated only when the vehicle needs battery internal circulation or deep thermal management control (usually high load conditions). If the vehicle is stationary or in a state requiring no cooling, part of the logic may be suspended.

• Trigger Conditions

  • When signal feedback anomalies at any of the above hierarchical levels persist beyond a preset time window (usually related to system sampling frequency), and it is confirmed not to be caused by instantaneous interference, the controller will solidify this fault code.
  • Once fuse blowout or key hardware communication interruption is detected, the system will immediately generate P1ADF00 and execute "Unable to Perform Battery Internal Circulation" strategy protection to block potential thermal runaway risk paths.