- ChangChun City, Jilin Province, China
by 
Welcome to this comprehensive technical guide on the FAW Engine Wiring Harness (Part No. 3724410-91W), the complete “nervous system” for the engine of the FAW Jiefang CA4251P66K24T1A3E5 6×4 diesel semi-trailer tractor.
The FAW Engine Wiring Harness is a complex, bundled assembly of wires, connectors, and sheathing that relays all data and power commands between the Engine Control Unit (ECU) and every sensor, actuator, and injector on the engine. The reliability of this one component is absolutely critical for engine function.
This guide is an essential resource for professional technicians, fleet managers, and parts specialists. We will deconstruct the entire FAW Engine Wiring Harness system, including the main harness assembly and the numerous, critical support brackets that protect it from vibration and heat, down to the smallest serviceable fastener.
The heart of this system is the ‘Engine Wiring Harness Assembly’ (3724410-91W). This is the main FAW Engine Wiring Harness itself, a single, complex part. This is not just a bundle of wires; it’s a precision-engineered component. Each wire is a specific gauge (thickness) and color, made from high-grade automotive TXL wire, which is designed to be resistant to oil, fuel, and extreme temperatures.
This main FAW Engine Wiring Harness connects to every critical component on the engine. This includes, but is not limited to:
The entire FAW Engine Wiring Harness is wrapped in high-temperature, abrasion-resistant conduit and tape. The connectors are all environmentally sealed, “weather-pack” style connectors with silicone gaskets to prevent water, salt, and dust from corroding the pins. A single corroded pin in one of these connectors can cause intermittent, “ghost” problems that are incredibly difficult to diagnose. The quality of the FAW Engine Wiring Harness is paramount to the truck’s reliability.
An engine, especially a heavy-duty diesel, is an environment of intense vibration and extreme heat. A FAW Engine Wiring Harness cannot simply be left to hang freely; vibration would cause the wires to chafe through their insulation, and proximity to the exhaust or turbo would melt them. The majority of this parts list is dedicated to the robust mounting system designed to prevent this.
The system includes a large number of dedicated brackets. The parts list shows:
This collection of 10 brackets forms the “skeleton” that the FAW Engine Wiring Harness is attached to. These brackets are precision-stamped from steel and are designed to bolt to specific, pre-tapped holes on the engine block and cylinder head. Their function is to create a secure, vibration-damped, and thermally-safe “path” for the FAW Engine Wiring Harness to follow. They route the harness away from moving parts (like the fan belt), high-heat sources (like the exhaust manifold and turbocharger), and sharp edges.
A key detail in this parts list is the duplication of bracket names. This is not an error; it indicates different parts for different, specific functions.
**Bracket 1 (3724411-91W vs. 3724021-51B):** The list calls for two units of ‘Bracket 1’ (Part No. -91W) and three units of ‘Bracket 1’ (Part No. -51B). This means there are five brackets total that are all designated as “Bracket 1” in the schematic. This typically means they are small, simple “P-clamps” or “C-clamps” that are used in multiple locations along the FAW Engine Wiring Harness to secure it to the main brackets or to the engine block. The two different part numbers likely refer to clamps of slightly different diameters or materials.
**Bracket 6 (3724416-91W vs. 3724026-54W):** Similarly, there are two different “Bracket 6” components. This usually indicates a more significant difference. For example, one bracket (e.g., -91W) might be a simple steel bracket for the “cold side” of the engine, while the other (e.g., -54W) might be a bracket with an integrated heat shield, or made from a different material, for mounting the FAW Engine Wiring Harness near a high-temperature component like the turbocharger oil lines.
This level of detail in the mounting system highlights the complexity of a modern FAW Engine Wiring Harness. It is not just about the wires; it is about protecting those wires for a service life of millions of miles and vibration cycles. The integrity of the FAW Engine Wiring Harness is completely dependent on this robust bracket system.
The entire FAW Engine Wiring Harness support system is held together by two simple, but critical, components.
**1. ‘Combination Bolt’ (CQ1401020):** The list calls for six of these. A “combination bolt” is a fastener with a pre-installed, captive washer (usually a spring-lock washer and a flat washer). These bolts are used to secure the 10 steel brackets to the engine. The captive spring-lock washer is essential; it provides constant tension, preventing the bolt from vibrating loose, which would leave a section of the FAW Engine Wiring Harness unsupported.
**2. ‘Plastic Zip Tie’ (T67417246):** The list calls for 16 of these. These are the final component in the assembly. The steel brackets (Item 2-8) create the “path,” and these plastic ties are what physically secure the FAW Engine Wiring Harness (Item 1) *to* those brackets. These are not standard hardware-store zip ties. They are automotive-grade, high-temperature, UV-resistant nylon ties, designed to remain durable and flexible for years without becoming brittle and snapping. A single snapped zip tie can allow a section of the FAW Engine Wiring Harness to fall against a hot or moving part, leading to a catastrophic failure.
The following table provides the complete, detailed breakdown of all 10 components identified in the ‘Engine Wiring Harness’ diagram for the FAW CA4251P66K24T1A3E5 tractor. A fully intact FAW Engine Wiring Harness and bracket system is essential for reliability.
| Mark | Part No. | Part Name | Quantity |
|---|---|---|---|
| 1 | 3724410-91W | Engine Wiring Harness Assembly | 1 |
| 2 | 3724413-91W | Engine Wiring Harness Bracket 3 | 1 |
| 3 | 3724411-91W | Engine Wiring Harness Bracket 1 | 2 |
| 4 | 3724417-91W | Engine Wiring Harness Bracket 7 | 1 |
| 5 | 3724021-51B | Engine Wiring Harness Bracket 1 | 3 |
| 6 | 3724414-91W | Engine Wiring Harness Bracket 4 | 1 |
| 7 | 3724416-91W | Engine Wiring Harness Bracket 6 | 1 |
| 8 | 3724026-54W | Engine Wiring Harness Bracket 6 | 1 |
| 9 | T67417246 | Plastic Zip Tie | 16 |
| 10 | CQ1401020 | Combination Bolt | 6 |
The specifications for the FAW Engine Wiring Harness are defined by its function as the master electrical nervous system, requiring extensive protection from heat and vibration. The entire FAW Engine Wiring Harness is a single, integrated assembly.
| Vehicle Application | FAW Jiefang CA4251P66K24T1A3E5 6×4 Tractor |
| Component Group | FAW Engine Wiring Harness |
| Main Harness Assembly | 1x (Part No. 3724410-91W) |
| System Type | Engine-Mounted Electrical Harness |
| Total Support Brackets | 10 (Various Part Nos.) |
| Bracket Fasteners | 6x Combination Bolts (CQ1401020) |
| Harness Fasteners | 16x Plastic Zip Ties (T67417246) |
| Key Features | Sealed connectors, high-temp conduit, vibration-damped mounting. |
| Primary Function | To connect the ECU to all engine sensors (input) and actuators (output). |
FAW parts, including the Cylinder Block Assembly, are packaged with care to ensure safe delivery. Each component is secured in protective materials to prevent damage during transit. The logistics network guarantees timely shipments worldwide, supporting efficient maintenance operations. Below is an image illustrating the standard packaging for FAW truck parts, showcasing the attention to detail in handling and storage.
This packaging approach minimizes the risk of corrosion or impact damage, ensuring that parts like the FAW Cylinder Block Assembly arrive in perfect condition. Customers can rely on FAW’s logistics for consistent quality and reliability.
FAW is one of China’s oldest and largest automotive manufacturers, with registered capital of RMB 35.4 billion yuan and total assets of RMB 457.83 billion yuan.
CHINA FAW GROUP CO., LTD. (short for FAW), formerly China First Automobile Works, can trace its roots back to Jul 15, 1953, when its first assembly plant started to be constructed. FAW is one of China’s oldest and largest automotive manufacturers, with registered capital of RMB 35.4 billion yuan and total assets of RMB 457.83 billion yuan.
China heavy truck sales global “five in a row”, heavy truck sales global “six in a row”, tractor sales for 16 consecutive years absolute leading industry.
