09/30/2026
The image shows a comprehensive master diagram of a car's complete body control harness, mapping out the central Body Control Module (BCM) and how it connects to power sources and peripheral components.
Core Components
• Central Brain: The Body Control Module (BCM) processes inputs and controls vehicle body electronics.
• Power Supply: The Fuse & Relay Box distributes power from the 12V battery system.
• Cabin & Dash: The Instrument Cluster, combination switch, and interior dome lights.
Peripheral Subsystems
• Doors & Windows: Front and rear door modules handle door locks, window motors, and side mirror controls.
• Exterior & Visibility: Connects headlights, tail lights, wipers, washer pumps, and the horn.
• Auxiliaries: Supports components like the license plate light, trunk release, and fuel tank door actuator.
Wire Color & Function Guide
• Red: 12V Battery (B+)
• Orange: Ignition (IG)
• Yellow: CAN High (Controller Area Network data)
• Green: CAN Low
• Blue: Signal (Switches and sensors)
• Purple: Motor Power
• Black: Ground (GND)
If you'd like help, let me know:
• Which specific circuit or component you are working on
• What symptom or issue the vehicle is experiencing
I can help trace the connections or explain how to test the system.
