Truck-Lite 77804 4-Outlet Electrical Distribution Module – 77 Series

Maintain dependable trailer lighting connections with the Truck-Lite 77804 4-Outlet Electrical Distribution Module, designed for compatible Truck-Lite 77 Series commercial trailer wiring harness systems.

Also known as a four-outlet junction block, this module provides four plug-in connection points for distributing electrical power and lighting signals through compatible trailer harnesses.

The 4-outlet design is especially useful for trailer wiring configurations requiring a central connection point for side marker lights, turn indicators, and other supported lighting circuits.

Truck-Lite's modular harness system uses keyed electrical connections, tin-plated brass contacts, and corrosion-protection features to help simplify electrical repairs and maintain reliable trailer lighting connections.

Whether you're replacing a damaged junction block, repairing trailer lighting problems, or servicing a commercial trailer electrical system, this four-outlet distribution module provides a replacement option for compatible installations.

Truck-Lite Part Number: 77804

Product Type: 4-Outlet Trailer Electrical Distribution Module

Harness System: Truck-Lite 77 Series

Number of Outlets: 4

IMPORTANT: THIS PRODUCT IS THE ELECTRICAL DISTRIBUTION MODULE ONLY. COMPLETE WIRING HARNESSES, LIGHTS, AND ADDITIONAL ELECTRICAL COMPONENTS ARE NOT INCLUDED UNLESS SPECIFICALLY LISTED.

Features & Benefits

• Truck-Lite 77804: Four-outlet distribution module for compatible Truck-Lite trailer wiring systems.

• Four Electrical Outlets: Connects up to four compatible wiring harness connections.

• Truck-Lite 77 Series Design: Intended for matching modular trailer lighting harness components.

• Keyed Plug-In Connections: Helps ensure compatible harness plugs are connected in the proper orientation.

• Tin-Plated Brass Contacts: Designed to provide electrical contact surfaces for commercial trailer applications.

• NYK-77 Corrosion Protection: Truck-Lite's distribution module system uses corrosion-preventative compound to help protect electrical connections.

• Serviceable Wiring Connections: Allows compatible harnesses to be disconnected and replaced during electrical repairs.

• Trailer Lighting Distribution: Supports applicable side marker, turn indicator, and auxiliary lighting connections.

• Heavy-Duty Trailer Application: Designed for compatible commercial truck and trailer wiring systems.

• Compact Four-Outlet Configuration: An alternative to larger distribution modules when the system requires only four connection points.

Product Specifications

What Does a 4-Outlet Trailer Junction Block Do?

Commercial trailers use multiple electrical harnesses to distribute power and lighting signals to different locations on the vehicle.

A 4-outlet electrical distribution module provides a central point where compatible trailer wiring harnesses can connect.

Rather than connecting every lighting circuit through separate field-wired splices, compatible Truck-Lite 77 Series harnesses connect through a modular plug-in arrangement.

Depending on the trailer's wiring configuration, the junction block may be used for:

• Side marker lighting connections

• Clearance lighting circuits

• Side turn indicators

• Auxiliary trailer lighting

• Compatible trailer lighting harness branches

The specific electrical functions depend on the connected wiring harnesses and the trailer's electrical design.

Designed for Truck-Lite 77 Series Wiring Systems

Truck-Lite's 77 Series harness system uses modular electrical connectors and distribution blocks for compatible commercial trailer lighting installations.

The system incorporates several features that simplify electrical connections and maintenance.

Keyed Connections

Compatible connectors are designed to fit in the intended orientation, helping prevent incorrect installation.

Tin-Plated Brass Electrical Contacts

Tin-plated brass contact surfaces provide electrical connections within the distribution module.

Corrosion-Preventative Compound

Truck-Lite specifies NYK-77 corrosion-preventative compound in its distribution module system to help protect electrical connections against moisture-related corrosion.

Harness Retention

The Series 77 system uses retaining components to help secure compatible electrical harness connections.

Important: Verify which retaining clips or mounting components are included with the specific module being purchased.

Four Outlets vs. Eight Outlets

Truck-Lite manufactures different electrical distribution modules to accommodate various trailer wiring configurations.

Truck-Lite 77804 – Four-Outlet Distribution Module

• Four compatible electrical harness connections

• Truck-Lite 77 Series application

• Suitable for specified smaller distribution arrangements

• Commonly used for side marker, turn indicator, and other supported lighting circuits

Truck-Lite 77808 – Eight-Outlet Distribution Module

• Eight compatible electrical harness connections

• Truck-Lite 77 Series application

• Used where the trailer wiring system requires additional connection points

The 77804 and 77808 are different modules. Do not assume that one can directly replace the other without verifying the trailer wiring and mounting arrangement.

Need the larger version?

Shop the Truck-Lite 8-Outlet Junction Block

Documented Commercial Trailer Applications

Truck-Lite 77804 appears in the electrical system parts breakdown for the Etnyre Blackhawk RTN Series trailer.

The same documented electrical arrangement also identifies:

These references demonstrate how the distribution modules work alongside other trailer wiring components.

Important: Parts appearing in the same trailer wiring diagram are not automatically direct plug-in replacements for one another. Confirm the exact electrical connection requirements before ordering.

Common Applications

This four-outlet junction block is intended for compatible electrical systems used on:

• Commercial roll-off trailers

• Dump trailers

• Flatbed trailers

• Heavy-duty equipment trailers

• Waste and recycling trailers

• Construction equipment trailers

• Commercial truck and trailer lighting systems

• Compatible Truck-Lite modular harness installations

Compatibility is determined by the harness system, outlet configuration, and electrical connection arrangement rather than the type of trailer alone.

Why Replace a Damaged Electrical Junction Block?

Trailer electrical components are exposed to moisture, road spray, dirt, vibration, and changing temperatures.

Over time, electrical connections and protective components may become damaged.

Common reasons to inspect or replace a distribution module include:

• Corroded electrical contacts

• Broken or damaged connector outlets

• Cracked module housing

• Loose or damaged harness connections

• Broken or missing retaining components

• Intermittent trailer lighting operation

• Electrical repairs involving a damaged junction block

A lighting problem can also be caused by failed lamps, poor ground connections, damaged wiring, or loose connectors.

Inspect the complete electrical circuit before replacing the distribution module.

How to Verify the Correct Replacement Junction Block

Before ordering, compare the replacement module with your existing electrical system.

1. Confirm the Original Part Number

Check for Truck-Lite 77804 on the existing module, packaging, or equipment parts diagram.

2. Count the Electrical Outlets

This product has four outlets. Verify that your original module uses the same number.

3. Compare Connector Shapes

Check that your trailer wiring harnesses have compatible keyed connectors.

4. Confirm the Harness System

Verify that your trailer uses compatible Truck-Lite 77 Series wiring components.

5. Check the Mounting Arrangement

Compare the original module's mounting configuration and available installation space.

6. Inspect the Existing Harnesses

Check the condition of the connector plugs, terminals, retainers, and wiring.

7. Identify Any Required Accessories

Determine whether the installation requires separate retaining hardware, filler plugs, or additional wiring components.

Important: The correct outlet count alone does not guarantee compatibility.

Frequently Asked Questions

What is Truck-Lite part number 77804?

Truck-Lite 77804 is a four-outlet electrical distribution module designed for compatible commercial trailer wiring harness systems.

How many electrical connections does it have?

The module provides four plug-in outlets for compatible harness connectors.

Is this a Truck-Lite 77 Series component?

Yes. Truck-Lite 77804 is identified as a four-way junction box for the 77 Series harness system.

Can it be used on a roll-off trailer?

Yes, if the trailer uses the correct Truck-Lite harness system and four-outlet module configuration.

What is the difference between Truck-Lite 77804 and 77808?

The 77804 has four outlets, while the 77808 has eight outlets. Confirm the correct module before ordering.

Does this junction block use screw terminals?

No. The 77804 is a plug-in harness distribution module, not a conventional open screw-terminal junction block.

Does the module have corrosion protection?

Truck-Lite's 77 Series distribution module system uses NYK-77 corrosion-preventative compound to protect electrical connections.

Does it include the wiring harnesses?

No. The trailer's lighting harnesses are separate components.

Does it include lights?

No. This product is the distribution module only.

Can I connect any trailer electrical plug to it?

No. The connectors must be compatible with the specific Truck-Lite 77 Series outlet arrangement.

Order Your Truck-Lite 4-Outlet Junction Block

Maintain reliable commercial trailer electrical connections with the Truck-Lite 77804 4-Outlet Electrical Distribution Module.

Designed for compatible Truck-Lite 77 Series harness systems, this junction block provides four keyed electrical outlets for trailer lighting and wiring distribution applications.

Truck-Lite Part Number: 77804

Number of Outlets: 4

Harness Family: Truck-Lite 77 Series

Order your Truck-Lite four-outlet junction block online today!

DISTRIBUTION MODULE ONLY — COMPLETE WIRING HARNESSES AND LIGHTING COMPONENTS NOT INCLUDED.

Need more electrical connections? Shop the Truck-Lite 8-Outlet Distribution Module.

Fitment Note: Verify the manufacturer part number, outlet count, connector arrangement, and mounting configuration before ordering.

SKU: