FAW Chassis Electrical Logic Assembly: An Essential Guide to the Complete Electrical System

Welcome to this essential technical analysis of the FAW Chassis Electrical Logic Assembly. This comprehensive system is the complete electrical backbone for the FAW Jiefang CA4251P66K24T1A3E5 6×4 diesel semi-trailer tractor. It functions as the vehicle’s central nervous system, managing everything from power generation and storage to lighting, sensor data, and safety system operation. This document deconstructs the entire assembly into its primary sub-systems and minimum serviceable units.

The term “Logic Assembly” signifies that this is far more than just a box of wires. The FAW Chassis Electrical Logic Assembly is an integrated network of high-amperage power lines, data communication harnesses, and intelligent components. It is responsible for the “logic” that governs the truck’s operation—for example, ensuring that the ABS system receives power and sensor readings, or that the correct signal light illuminates when the driver hits the switch.

For technicians, fleet managers, and parts specialists, understanding this system is critical. A failure is rarely just a single wire; it’s often a component within a larger, interconnected “logic” group. This guide will break down the FAW Chassis Electrical Logic Assembly into its three core functional areas: Power Generation & Storage, The Harness & Distribution Network, and The End-Point Components (Lights, Sensors, and Switches).

Core 1: Power Generation & Storage Assemblies

The foundation of the FAW Chassis Electrical Logic Assembly is its ability to create, store, and distribute high-amperage current. This is handled by three primary “overall purchase” components, which are typically replaced as complete units.

1. Alternator Assy (3701010-36D): This is the power plant of the truck. Driven by the engine’s accessory belt, the alternator generates AC current, which it then rectifies to DC current to power all onboard systems and, crucially, to recharge the batteries. A failure here will cause the FAW Chassis Electrical Logic Assembly to drain the batteries, bringing the truck to a halt. This is a primary serviceable assembly.

2. Battery Assy (3703010-1086 & 3703010A1086): The parts list calls for two battery assemblies. This is standard for a 24-volt heavy-duty system, with two 12V batteries connected in series. These assemblies are the truck’s energy reservoirs, providing the immense cranking amps needed for the ‘Starter assy’ and stabilizing the voltage for the entire FAW Chassis Electrical Logic Assembly. Batteries are the most frequently replaced component in this group.

3. Starter Assy (3708010-530-C00): This is the single largest consumer of electricity on the vehicle. Its sole function is to engage the engine’s flywheel and turn the crankshaft, initiating combustion. It draws its power directly from the batteries via a heavy-gauge cable, which is a key part of the FAW Chassis Electrical Logic Assembly‘s power distribution. It is considered a non-serviceable unit in the field and is replaced as a whole.

Core 2: The “Logic” – Harnesses & Distribution Network

This section represents the true “logic” of the FAW Chassis Electrical Logic Assembly. These harnesses are the complex web of wires that act as the vehicle’s nervous system, carrying power and data signals to every corner of the chassis. They are not simple wires, but complex, pre-formed assemblies designed to fit the chassis perfectly and resist vibration, heat, and corrosion.

These components are arguably the most complex part of the entire FAW Chassis Electrical Logic Assembly. They are bundled, insulated, and terminated with high-grade, multi-pin connectors that lock into place.

Main Chassis Harnesses (e.g., 3724260-96S, 3724265-97R): The parts list identifies several “chassis electric harness assy” components. These are the main arteries. The ‘Left’ and ‘Right’ harnesses run the length of the truck frame, carrying signals for the rear combination lamps, ABS sensors, and trailer connections.

Power Distribution (e.g., 3724100A92W, 3722155A92W): This group includes critical power-carrying lines. The ‘Power line assy-battery to starting relay…’ (3724100A92W) is the main heavy-gauge cable for the starter. The ‘Chassis electric fuse box & bracket assy’ (3722155A92W) is a critical minimum serviceable unit; it is the central protection point for the entire FAW Chassis Electrical Logic Assembly. While the harness is one part, the fuses *within* it are the MSUs.

System-Specific Harnesses (e.g., 3724115-61B, 3724410-91W): The FAW Chassis Electrical Logic Assembly is also composed of specialized sub-harnesses. The ‘ABS main harness assy for towing vehicle’ (3724115-61B) is a safety-critical component dedicated *only* to the anti-lock braking system. Similarly, the ‘Engine electric harness assy’ (3724410-91W) acts as the bridge, allowing the chassis to communicate with the engine’s electronic control unit (ECU).

Service for these components is precise. A single damaged pin or a corroded wire can disable an entire sub-system. In most cases, a damaged harness is replaced as a complete assembly, as field repairs are unreliable.

Core 3: End-Point Components (Lights, Sensors & Switches)

These components are the “senses” and “voice” of the FAW Chassis Electrical Logic Assembly. They are the inputs (sensors, switches) and outputs (lights, horns) that the driver and the vehicle’s ECUs interact with. These are the most common minimum serviceable units (MSUs).

Lighting Assemblies (e.g., 3711015-91W-C00, 3716015-91W-C00): The parts list includes the complete ‘Left/Right front combination lamp assy’ and ‘Left/Right rear combination lamp assy’. These assemblies are overall purchase parts, but the bulbs *inside* them are the true MSUs. This group also includes the ‘Side marker lamp assy’ (3733010-55A) and the ‘Fog lamp’ assemblies (3732015-91W-C00), which are all part of the integrated FAW Chassis Electrical Logic Assembly.

Sensors (e.g., 3757010-2000-C00, 3802020-76A): These are the “nerves” that send data back to the driver and the ECUs. The ‘Air pressure sensor’ (3757010-2000-C00) is critical for the brake system. The ‘Electronic tachograph sensor assy’ (3802020-76A) provides vehicle speed data. The ‘Fuel sensor’ (3806040-54W) reports the fuel level. These sensors are all MSUs that can be individually diagnosed and replaced.

Switches & Actuators (e.g., 3736010-61B, 3754010-63U): These components translate physical action into electrical signals or vice-versa. The ‘Power master switch assy’ (3736010-61B) is the main cut-off for the entire system. The ‘Differential lock switch assy’ (3834050-A0E) sends a signal to engage the axle. Actuators like the ‘Solenoid valve assy’ (3754010-63U) and the ‘Fuel shutoff solenoid valve’ (3806045-1516) are where the FAW Chassis Electrical Logic Assembly performs physical work, turning electrical commands into mechanical motion.

FAW Chassis Electrical Logic Assembly Parts List

The following table provides the complete, detailed breakdown of all 53 components identified in the FAW Chassis Electrical Logic Assembly diagram for the FAW CA4251P66K24T1A3E5 tractor.

Technical Specifications and Assembly Context

The specifications for the FAW Chassis Electrical Logic Assembly are defined by its function as the primary electrical distribution and control network for the vehicle. This system is engineered for durability, serviceability, and reliable operation in demanding, high-vibration environments.