Reese Towpower 78119 Wiring Adapter Instruction Manual

1. Product Overview

The Reese Towpower 78119 Wiring Adapter is designed to convert a vehicle's 7-way blade connector to a standard 4-flat or 5-flat trailer connector. This adapter includes a built-in LED circuit tester for immediate connection verification and an integrated 12-volt power outlet for auxiliary devices.

Key features include:

• Converts 7-way blade connector to 4-flat or 5-flat.
• Integrated LED circuit tester for connectivity confirmation.
• Built-in 12-volt power outlet.
• Attached dust cover for terminal protection.
• Extra attached terminal plug to cover the 5th post when using 4-flat.

Figure 1: Reese Towpower 78119 Wiring Adapter

2. Setup and Installation

This adapter is designed for straightforward plug-and-play installation. Ensure your vehicle's ignition is off before connecting or disconnecting the adapter.

2.1 Connecting to the Vehicle

1. Locate the 7-way blade connector on your vehicle. This is typically found near the hitch receiver.
2. Align the adapter's 7-way input with the vehicle's 7-way connector.
3. Push the adapter firmly into the vehicle's connector until it is securely seated.

2.2 Connecting to the Trailer

1. Identify whether your trailer uses a 4-flat or 5-flat connector.
2. Align the trailer's connector with the corresponding 4-flat or 5-flat output on the adapter.
3. Push the trailer connector firmly into the adapter's output. If using a 4-flat trailer, ensure the attached terminal plug covers the 5th post of the adapter's 5-flat output to prevent corrosion.

Figure 2: Adapter showing LED tester and 4/5-flat outputs

3. Operation

3.1 LED Circuit Tester

The adapter features a built-in LED circuit tester. Once the adapter is connected to the vehicle and the vehicle's lights or turn signals are activated, the corresponding LEDs on the adapter will illuminate to confirm a complete circuit. This allows for quick verification of proper wiring connections before towing.

3.2 12V Power Outlet

A 12-volt power outlet is integrated into the adapter. This outlet can be used to power various 12V accessories, such as portable coolers or phone chargers, directly from your vehicle's 7-way power supply.

3.3 Dust Cover and 5th Post Plug

When the adapter is not in use, or when only a 4-flat trailer is connected, utilize the attached dust cover to protect the terminals from dirt, moisture, and corrosion. The extra attached terminal plug should be used to cover the 5th post of the 5-flat output when only a 4-flat connection is required.

4. Maintenance

• Keep Terminals Clean: Regularly inspect and clean the electrical terminals on both the adapter and your vehicle/trailer connectors to ensure optimal conductivity. Use a dielectric grease for added protection against corrosion.
• Utilize Dust Covers: Always use the attached dust cover when the adapter is not connected to a trailer to protect the internal components from environmental elements.
• Inspect for Damage: Periodically check the adapter for any signs of physical damage, such as cracks in the housing or bent pins. Replace the adapter if any damage is found.

5. Troubleshooting

• No Power/LEDs Not Lighting: If the adapter's LEDs do not light up or the 12V outlet has no power, first check the vehicle's fuse box for a blown fuse related to the trailer wiring. A common issue is a blown fuse for the 12V auxiliary power pin (Pin 4) on the 7-way connector.
• Intermittent Connection: Ensure all connections are firm and free of debris. Wiggle the adapter and trailer connector slightly to see if the connection stabilizes. Clean terminals if necessary.
• "Trailer Connected, Not Setup" Alert (Ford F-Series): Some vehicles, particularly Ford F-Series trucks with a 5th wheel package, may display this alert when the adapter is used solely for the 12V power outlet without a trailer. To resolve this, you may need to set up a 'dummy' trailer profile in your vehicle's settings (e.g., name it "Cooler") to prevent the alert and ensure all vehicle systems function correctly.
• Incorrect Light Function: If trailer lights are not functioning as expected, verify the wiring of your trailer's connector. The LED tester on the adapter can help identify which circuits are receiving power from the vehicle.

6. Specifications

7. Compatibility

The Reese Towpower 78119 adapter is designed for specific wiring configurations. Refer to the diagram below to understand its application within various towing setups.

Figure 3: Reese Towpower Adapter Compatibility Chart (Partial)

This adapter specifically converts a vehicle's 7-way blade connector to a trailer's 4-flat or 5-flat connector, while also providing a 12-volt power outlet and LED testing capabilities.

8. Warranty and Support

For specific warranty information, please refer to the documentation included with your purchase or visit the official Reese Towpower website. Warranty terms and conditions may vary.

For technical support or further inquiries, please contact Reese Towpower directly:

• Website: ReeseBrands.com
• Phone: 1-800-234-6992