BYD ATTO 3 / Yuan Plus P1A4100 P1A3400 Power Battery Pre-Charge & Contactor Fault OEM Diagnostic Guide

Product: Instant Digital Download (PDF)

Diagnose BYD ATTO 3 / Yuan Plus power battery pre-charge, contactor sintering, contactor feedback and dual-circuit power-supply faults using the applicable OEM diagnostic procedures, VDS checks and guided decision paths.

Years Covered:

2022, 2023, 2024, 2025

Vehicle Specification:

SC2E, e-Platform 3.0 400V, FWD, RHD

Excludes:

2026+ BYD ATTO 3 Evo, 800V RWD/AWD architecture, 74.8 kWh Cell-to-Body battery pack, and Left-Hand Drive (LHD) variants.

DTCs Covered

• P1A4100 — Main Contactor Sintering Fault
• P1A4200 — Negative Contactor Sintering Fault
• P1A3E00 — Main Contactor Feedback Fault
• P1A3F00 — Pre-Charging Contactor Feedback Fault
• P1A3D00 — Negative Terminal Contactor Recheck Fault
• P1A3400 — Pre-Charging Failure Fault
• P1A5B00 — Contactor Disconnection Due to Dual-Circuit Power Supply Fault

Diagnostic Coverage

• OEM high-voltage safety and electrical precautions
• Diagnostic prerequisites and test conditions
• DTC confirmation, clearing and fault-code recheck
• Intermittent-fault diagnosis
• Main contactor sintering diagnosis
• Negative terminal contactor sintering diagnosis
• VDS active-control contactor testing
• Power battery pack terminal-voltage measurement
• Main contactor feedback diagnosis
• Negative terminal contactor feedback/recheck diagnosis
• Pre-charging contactor feedback diagnosis
• Integrated intelligent front-wheel drive controller software check and update
• P1A3400 pre-charge failure diagnosis
• Pre-charging time > 1200 ms fault condition
• Pre-charge current and bus-voltage checks
• Battery-pack fuse inspection
• High-voltage wiring harness and connector checks
• Electronic-control capacitor/wiring diagnosis
• P1A5B00 power-domain-controller fault-code diagnosis
• Right body domain controller network check
• Right Body Domain Controller CAN Off - Energy Network diagnostic handoff
• OEM diagnostic decision sequences
• OEM-directed component repair or replacement actions for failed branches

Included Links to OEM Source Material

Reference links are provided within the guide for:

• Complete OEM Diagnostic Manual
• Electronic Wiring Diagram
• Repair Manual

The linked OEM source documents are separate reference resources and are not included with this Diagnostic Guide.