P157400 Power Supply Equipment Failure: Technical Definition and System Logic Analysis

Deep Fault Definition

P157400 (Power Supply Equipment Failure) is a critical diagnostic fault code used in the vehicle electrical system to identify when the AC Charging Power Management Unit enters an abnormal state. The system monitors the connection status and input quality of external power supply equipment in real-time through highly integrated control units. When the vehicle enters AC charging mode, and the system expects to receive valid signals at specified interaction interfaces, if physical power input loss or logical determination not meeting preset safety thresholds is detected, the control unit will record this fault code to identify the risk of interruption in the power supply chain. This definition covers the complete voltage monitoring loop from high-voltage interlock to the charging power port, ensuring that the vehicle does not execute incorrect energy management instructions under abnormal power supply conditions.

Common Fault Symptoms

When the system stores P157400 fault code, car owners and drivers may observe the following specific driving experience feedback or dashboard indications:

• The vehicle cannot normally enter AC charging state;
• Charging indicator light on the instrument panel is extinguished or not illuminated;
• Vehicle Power Management System (BMS) refuses to accept external AC power input commands;
• Vehicle range display shows no abnormality, but energy replenishment function is completely unavailable.

Core Fault Cause Analysis

Regarding the fault determination for P157400, technical analysis mainly categorizes potential risk sources into hardware or logic failure in the following three dimensions:

• Charging Power Side Abnormality: Unstable external AC power grid supply, or interruption of external AC power supply caused by charging piles or cables;
• On-Board Charger (OBC) Internal Failure: Physical damage or circuit breakage in the vehicle's internal charging power module, leading to inability to process input voltage;
• Controller Logic Calculation Deviation: Although hardware lines are unblocked, system control unit makes errors in logical matching between processing S2 switch signals and voltage feedback.

Technical Monitoring and Trigger Logic

The generation of this fault code follows strict timing and state logic judgment rules, with specific monitoring mechanisms as follows:

• Monitoring Target: System focuses on monitoring the validity of AC input voltage (AC Voltage Input) and physical closure status of the charging interface.
• Working Condition Requirement: This monitoring is activated only under Vehicle AC Charging State. Judgment is not triggered when static or not connected to charging mode.
• Interaction Condition: Control unit waits for operator or system automatic execution of Closing S2 Switch action.
• Judgment Threshold and Logic:
  • System starts timing immediately after detecting S2 Switch Closed signal;
  • If within Specified Time, monitoring channel always Does Not Detect AC Voltage Input;
  • When above conditions are met simultaneously and timeout confirmed, fault code P157400 is generated.

This logic ensures that the system provides P157400 warning to the driver only after confirming that the power supply equipment indeed exists substantial faults (such as power loss or internal open circuit), preventing false alarms due to transient interference.