FAW Driver Cab Fuse Box 1 Assembly: A Critical Analysis of 4 Core Electrical Components

Welcome to this critical technical guide on the FAW Driver Cab Fuse Box 1 Assembly (Assembly 580). This is a primary electrical distribution and protection hub for the FAW Jiefang CA4251P66K24T1A3E5 6×4 diesel semi-trailer tractor. This assembly is the central “logic gate” that protects the truck’s vital electrical circuits from catastrophic failure.

The FAW Driver Cab Fuse Box 1 Assembly is a “logic” system with one vital function: to safely distribute power from the battery to multiple, individual circuits (like lights, wipers, and computers). Its “logic” lies in its use of fuses and relays, which act as sacrificial, protective “weak links.”

This in-depth guide is an essential resource for professional diesel technicians and electricians. We will deconstruct the entire FAW Driver Cab Fuse Box 1 Assembly into its 4 serviceable component types as listed: the ‘Driver cab fuse box 1 assembly’ (3722020-92W), the ‘Four-pin relay assembly’ (3752015-91W), and the 5A and 10A blade fuses.

Core “Logic” 1: The ‘Driver Cab Fuse Box’ (3722020-92W)

The heart of the FAW Driver Cab Fuse Box 1 Assembly is the ‘Driver cab fuse box 1 assembly’ (3722020-92W) itself. This is the main “box” or “housing.” It is a complex, molded polymer case with an integrated internal circuit board or “bus bar” system.

This component’s “logic” is to act as a central “power grid” for the cab. It receives a few large, high-amperage power cables directly from the truck’s battery (Assembly 556) and then subdivides that power into dozens of smaller, protected circuits. Each circuit is protected by one of the blade fuses.

This modular “logic” is a critical design feature. It allows technicians to easily isolate and diagnose electrical problems. Instead of one massive, tangled wiring harness, the FAW Driver Cab Fuse Box 1 Assembly provides a clean, serviceable, and labeled “junction point” for all cab electronics, from the ‘Combination Switch’ (Assembly 559) to the ‘Interior Lights’ (Assembly 565).

Core “Logic” 2: The ‘Four-Pin Relay Assembly’ (3752015-91W)

A key component of the FAW Driver Cab Fuse Box 1 Assembly is the ‘Four-pin relay assembly’ (3752015-91W). A relay is an “electrically-operated switch.” This is a critical “logic” device that uses a small amount of power to control a large amount of power.

Here is the “logic” of a relay in the FAW Driver Cab Fuse Box 1 Assembly:

• A high-power device (like a headlight or a blower motor) draws a lot of current (e.g., 15-20 amps).
• It would be dangerous and inefficient to run this high-amperage wire all the way up the steering column to the “on/off” switch and back. The switch would be large, hot, and a fire risk.
• Instead, the “on/off” switch (like the ‘Combination Switch’, Assembly 559) sends a very small, low-amperage (e.g., 0.1 amp) signal to the “control” pins of this relay.
• This small signal energizes a tiny electromagnet inside the relay, which “pulls” a large, heavy-duty internal switch, closing the high-power circuit. The high-amperage power flows directly from the fuse box, through the relay, and to the device, traveling only a short distance.

This “logic” is safer, more efficient, and allows for the use of smaller, more reliable driver-facing switches. A failed relay in the FAW Driver Cab Fuse Box 1 Assembly is a common fault, typically presenting as a circuit that is “dead” even though the fuse is good.

Core “Logic” 3: The Fuses (3722011-50, 3722012-50)

The primary “logic” of the FAW Driver Cab Fuse Box 1 Assembly is protection, and this is the job of the fuses. This list details two types:

• ‘5A blade fuse’ (3722011-50) – 2 units
• ’10A blade fuse’ (3722012-50) – 1 unit

A fuse is a “sacrificial” safety device. It is a small piece of metal inside a plastic housing that is designed to melt (or “blow”) at a specific amperage (e.g., 5 amps or 10 amps).

Here is the “logic” of a fuse in the FAW Driver Cab Fuse Box 1 Assembly:

• A “short circuit” is the most dangerous electrical fault. This is when a power wire accidentally touches the metal chassis (ground) due to a chafed wire or a failed component.
• When this happens, the circuit is “un-restricted,” and a massive, uncontrolled amount of current (hundreds of amps) will flow from the battery. This current instantly superheats the wire, melting the insulation and causing a **vehicle fire**.
• The fuse is the “logic” that prevents this. The fuse is the *thinnest* point in the circuit. During a short circuit, *before* the main wire can even get warm, the tiny metal link inside the fuse “blows” in a millisecond, instantly breaking the circuit and cutting off the power.

The FAW Driver Cab Fuse Box 1 Assembly is populated with many of these fuses, each one precisely rated for its specific circuit. A 5A fuse (for a low-power circuit like a sensor) will blow, while a 10A fuse (for a higher-power circuit like a light) will not. Replacing a “blown” 10A fuse with a 20A fuse is a critical mistake that will bypass this safety logic and create a fire hazard.

FAW Driver Cab Fuse Box 1 Assembly Parts List

The following table provides the complete, detailed breakdown of all 4 components identified in the ‘Driver Cab Fuse Box 1 Assembly’ (580) diagram for the FAW CA4251P66K24T1A3E5 tractor.

Technical Specifications and Assembly Context

The specifications for the FAW Driver Cab Fuse Box 1 Assembly are defined by its function as a central, safety-critical power distribution and circuit protection module. The FAW Driver Cab Fuse Box 1 Assembly is essential for the reliability and safety of all cab electronics.