FAW Rear Combination Lamp Logic Assembly: A Critical Breakdown of the 4 Core Components

Welcome to this critical technical guide on the FAW Rear Combination Lamp Logic Assembly (Assembly 568). This is the complete, multi-part, serviceable tail light and signaling unit for the FAW Jiefang CA4251P66K24T1A3E5 6×4 diesel semi-trailer tractor. This assembly is the primary signaling and safety “logic” system for the rear of the vehicle, essential for legal compliance and accident prevention.

The FAW Rear Combination Lamp Logic Assembly is a “logic” system with two main purposes: “to be seen” and “to signal intent.” It is not a single light, but a complex, integrated housing that combines multiple light sources. Its “logic” is to provide legally-compliant illumination for brake lights, tail lights (position lamps), turn signals, and reverse lights in one sealed, durable, and serviceable unit.

This in-depth guide is an essential resource for professional technicians, fleet managers, and parts specialists. We will deconstruct the entire FAW Rear Combination Lamp Logic Assembly into its 4 core serviceable components as listed: the ‘Left’ (3716015-91W-C00) and ‘Right’ (3716020-91W-C00) lamp housings, and the critical fastening hardware that ensures a vibration-proof and watertight installation.

Core Components: The ‘Left’ (3716015-91W-C00) & ‘Right’ (3716020-91W-C00) Assemblies

The main components of this system are the ‘Left rear combination lamp assembly’ (3716015-91W-C00) and the ‘Right rear combination lamp assembly’ (3716020-91W-C00). These are the two complete “tail light” units. They are designed as mirror images of each other and are the primary signaling devices at the rear of the tractor. The “combination” logic is the key design feature of the FAW Rear Combination Lamp Logic Assembly.

In older vehicles, each function (brake, signal, reverse) was a separate, individual lamp. The modern FAW Rear Combination Lamp Logic Assembly integrates all of these functions into a single, aerodynamically efficient, and sealed unit. This simplifies manufacturing, reduces drag, and provides a clean, modern aesthetic.

Each of these assemblies contains several distinct “logic” circuits, each critical for safety:

• **Brake Light (Red):** This is the most critical safety “logic.” It provides an instant, high-intensity red light the moment the driver touches the brake pedal (see Assembly 541). This “logic” is often provided by **LEDs** because they illuminate **0.2 seconds faster** than an incandescent bulb. At 60 mph (100 km/h), this gives the driver behind an extra 5.6 meters (18 feet) of stopping distance, which can be the difference in an accident.
• **Turn Signal / Indicator (Amber):** This is the flashing amber light, a critical safety “logic” component for signaling intent to turn or change lanes. A bright, clearly visible signal from the FAW Rear Combination Lamp Logic Assembly is essential for preventing lane-change accidents with passenger cars in the truck’s blind spot.
• **Tail Light / Position Lamp (Red):** This is a low-intensity red light that activates with the headlights. Its “logic” is to provide “presence,” marking the rear corners of the wide tractor at night, preventing rear-end collisions.
• **Reverse Light (White):** This provides a bright, white light to illuminate the area behind the truck, a critical “logic” for safely backing up to a trailer or loading dock in the dark. It also acts as a visual signal to anyone behind the truck that the vehicle is in reverse.

The “Logic” of Durability: Construction and Sealing

The FAW Rear Combination Lamp Logic Assembly is designed to survive in one of the most hostile environments on a vehicle. It is constantly subjected to vibration, water spray, road salt, gravel, and extreme temperature swings. Its “logic” is therefore one of extreme durability.

**1. Lens Construction:** The outer “lens” is not glass. It is a high-impact, **polycarbonate** plastic. This “logic” is critical. Glass would shatter from a single rock thrown by the drive wheels. Polycarbonate is virtually shatterproof, resisting impacts. Furthermore, the lens is **UV-stabilized** (to prevent the “yellowing” and “fogging” that plagues cheap plastic) and “hard-coated” (to resist scratching and hazing). This ensures the FAW Rear Combination Lamp Logic Assembly remains bright and clear for years.

**2. Housing and Sealing:** The “body” of the FAW Rear Combination Lamp Logic Assembly is a robust, vibration-dampening ABS or polymer housing. This housing is **hermetically sealed** to the lens, typically using a hot-melt butyl rubber sealant. This “logic” is to make the entire unit completely waterproof (often to an IP67 rating). A failed seal is a “logic” failure. If water enters the assembly, it will short out the internal circuit boards (if LED) or corrode the bulb sockets (if incandescent), leading to a “light-out” failure that will put the truck out of service.

**3. Illumination Logic (LED):** As mentioned, the “logic” of modern heavy-duty lighting is **LED (Light Emitting Diode)**. An incandescent bulb has a fragile, thin tungsten filament that is extremely susceptible to breaking under the constant, high-frequency vibration of a diesel truck. An LED is a solid-state, “shock-proof” device with no moving parts or fragile filaments, making it virtually immune to this vibration. This “fit-and-forget” reliability is the core “logic” of the FAW Rear Combination Lamp Logic Assembly, saving fleets thousands in maintenance costs and downtime.

Core Component 2: The Fastener “Logic” System

The FAW Rear Combination Lamp Logic Assembly is mounted to the chassis (often to the rear frame crossmember or a dedicated light bracket). The parts list details a specific, three-part fastener “logic” to ensure a secure, vibration-proof, and serviceable mount. The list calls for 4 of each, likely two for each lamp assembly.

This system (which uses studs from the lamp body) consists of:

• **’Gasket’ (Q40110) – 4 units:** This is the flat washer. Its “logic” is to be placed first, directly against the truck’s chassis bracket. It provides a wide, flat surface for the other hardware, preventing the ‘Spring gasket’ from “digging into” and damaging the bracket’s paint or metal.
• **’Spring gasket’ (Q40310) – 4 units:** This is the “lock washer.” This is the most critical “logic” component of the fastener system. It is a split, angled ring of spring steel. When the ‘Hex nut’ is tightened, this washer is flattened, exerting constant spring tension *against* the nut. This tension makes it physically impossible for the nut to vibrate loose from road shock.
• **’Hex nut’ (CQ34010) – 4 units:** This is the final fastener that provides the clamping force.

A loose FAW Rear Combination Lamp Logic Assembly would quickly fail. The vibration would cause the electrical connector to “fret” (wear out), leading to intermittent lights. It would also cause the housing itself to crack from the stress. This simple, three-part “gasket-spring-nut” logic is an essential, engineered solution to ensure the FAW Rear Combination Lamp Logic Assembly remains secure for its entire service life. The ‘Combination Bolt’ (CQ1460625) (8 units) is likely used to secure the *brackets* that these lamps mount to, providing the same vibration-proof “combination” (bolt + captive washer) logic.

FAW Rear Combination Lamp Logic Assembly Parts List

The following table provides the complete, detailed breakdown of all 4 component types (totaling 18 pieces) identified in the ‘Rear Combination Lamp Logic Assembly’ (560) diagram for the FAW CA4251P66K24T1A3E5 tractor.

Technical Specifications and Assembly Context

The specifications for the FAW Rear Combination Lamp Logic Assembly are defined by its function as a multi-light, sealed, and aimable unit. The FAW Rear Combination Lamp Logic Assembly is a key safety and compliance component.