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Factory cutout in truck bed required for installation
Color: Black
Finish: Blank
Installation Time Exact (Minutes): 0
There is nothing like the luxury and power that go along with heavy-duty towing. 5th wheel RVs offer a deluxe, home-away-from-home experience unlike any other, while gooseneck trailers possess a strength that far surpasses most other trailer options. As with any trailer, however, 5th wheels and goosenecks must be equipped with the proper lighting and electrical systems, and tend to require even more complex connectors than a standard receiver-type trailer setup. Make things simple with a CURT 5th wheel / gooseneck extension harness. These wiring harnesses are designed to put an extra connector socket in the bed of your pickup truck while still retaining power to the rear connector socket mounted on your bumper. This is done by plugging into the back of the existing original equipment (OEM) harness and routing through the body of the truck to a hole in the truck bed, providing a connector that is ready to accommodate your 5th wheel or gooseneck trailer.
This CURT extension harness provides connection points for both 4-way flat and 7-way RV blade connectors, and it comes in a length of 7'. It is compatible with select models of Chevrolet, Dodge, Ford, GMC, Nissan, Ram and Toyota (to verify your vehicle compatibility, see the CURT application guide at curtmfg.com). When you need a towing electrical solution that allows you to switch back and forth between your receiver hitch and specialized trailer hitch, CURT gets you plugged in
CURT offers a variety of high-quality trailer hitches and accessories for select vehicle models. Find the perfect fit for your towing needs at TowUniverse.
CURT, a Lippert brand, offers a complete line of towing products and is the leading manufacturer of custom-fit trailer hitches. We offer the broadest selection of custom-fit hitches, and each one is designed, welded, and coated in Wisconsin.
CURT is also a leader in flat towing products, as well as 5th wheel, gooseneck, and weight distribution hitches, ball mounts, electrical components, cargo solutions, and other towing accessories.
For everything from passenger cars and vans to full-size pickups and SUVs, CURT is 'The First Name in Towing Products®.'
Experts available to answer your questions
Call 888-634-9494One-Year Limited
8 compatible vehicles
| Year | Make & Model | Notes |
|---|---|---|
| 2019 - 2026 | Chevrolet Silverado 1500 | Installation Location - Installation Time - |
| 2022 | Chevrolet Silverado 1500 LTD | Installation Location - Installation Time - |
| 2020 - 2026 | Chevrolet Silverado 2500 HD | Installation Location - Installation Time - |
| 2020 - 2026 | Chevrolet Silverado 3500 HD | Installation Location - Installation Time - |
| 2019 - 2026 | GMC Sierra 1500 | Installation Location - Installation Time - |
| 2022 | GMC Sierra 1500 Limited | Installation Location - Installation Time - |
| 2020 - 2026 | GMC Sierra 2500 HD | Installation Location - Installation Time - |
| 2020 - 2026 | GMC Sierra 3500 HD | Installation Location - Installation Time - |
Yes, the CURT 7' Custom Wiring Extension Harness (Adds 4-Way, 7-Way RV Blade to Truck Bed) 56003 (Part #BKDK56003) is designed to fit the 2019-2026 Chevrolet Silverado 1500.
The CURT 7' Custom Wiring Extension Harness (Adds 4-Way, 7-Way RV Blade to Truck Bed) 56003 (Part #BKDK56003) fits the following vehicles: 2019-2026 Chevrolet Silverado 1500; 2022 Chevrolet Silverado 1500 LTD; 2020-2026 Chevrolet Silverado 2500 HD; 2020-2026 Chevrolet Silverado 3500 HD; 2019-2026 GMC Sierra 1500; 2022 GMC Sierra 1500 Limited; 2020-2026 GMC Sierra 2500 HD; 2020-2026 GMC Sierra 3500 HD. Always verify your specific year, make, and model before ordering.
The CURT 7' Custom Wiring Extension Harness (Adds 4-Way, 7-Way RV Blade to Truck Bed) 56003 (Part #BKDK56003) fits 2019-2026 Chevrolet Silverado 1500 models. The 2026 model year is the last year covered by this part number. For newer models, check for an updated version.
The CURT 7' Custom Wiring Extension Harness (Adds 4-Way, 7-Way RV Blade to Truck Bed) 56003 (Part #BKDK56003) Typical installation time is . Basic hand tools are typically all you need.
Part 56003 is a Curt Manufacturing wiring location extension harness designed to extend the reach of a truck's factory 7-way trailer connector. It allows you to connect a trailer at a different location on the vehicle by routing the wiring harness from the factory connector to a rear cutout in the truck bed, where a 7-way socket and 4-flat connector are mounted.
Part 56003 is designed for trucks with a factory 7-way trailer connector mounted to the hitch or bumper at the rear of the vehicle. The manual does not specify which truck models or years are compatible. Contact Curt Manufacturing or your dealer with your vehicle's year, make, and model to confirm fitment.
No. Part 56003 requires a factory 7-way trailer connector already mounted to the hitch or bumper at the rear of the vehicle. The extension harness connects between the factory connector and a new 7-way socket in the truck bed. If your truck does not have a factory 7-way connector, this product will not work.
The extension harness includes a male/female 7-way connector, a 7-way socket, a 4-flat connector, cable ties for securing the harness to the vehicle, and a filler plug. The manual does not specify the exact quantity of cable ties or provide a complete parts list.
Yes. Step 1 requires you to locate the vehicle battery on the driver side under the hood and disconnect the negative battery terminal before beginning installation. You will reconnect it in Step 7 after the installation is complete.
The factory 7-way trailer connector is mounted to the hitch or bumper at the rear of the vehicle. It will be similar in appearance to the connector on the extension harness. Locate it before beginning installation.
Carefully release the locking clip on the 7-way connector to separate it from the vehicle wiring harness. Do not force the connector; the locking clip must be fully released before the connector will separate.
Insert the male/female end of the extension harness between the separated factory connectors. Make sure both connectors are fully inserted with locking tabs in place. The connectors must be fully seated and locked before proceeding.
The filler plug is located under the vehicle on the driver's side. Remove it by squeezing the retention clips and pushing on the plug. This opening is where you will route the wiring harness.
Route the wiring harness from the filler plug location up to the cutout in the truck bed. Insert the harness connector into the rear of the provided 7-way socket, ensuring connectors are fully inserted with locking tabs in place. Then insert the 7-way/4-flat connector into the cutout, making sure it snaps back into place.
After testing for proper function, secure the extension harness cable to the vehicle using the cable ties provided with the product. Ensure the harness will not pinch or bind when operating.
Before reconnecting the negative battery terminal in Step 7, test the installation for proper function using a test light or by connecting a properly wired trailer. This ensures the wiring is correct and the connectors are fully seated before power is restored.
Do not exceed the product rating or the tow vehicle lamp load rating, whichever is lower. This means the extension harness has a maximum electrical load it can safely handle, and your vehicle's lighting system also has a maximum load. You must stay below both limits. Exceeding either could cause electrical failure or fire.
Test for proper function by using a test light or connecting a properly wired trailer. A test light will show whether power is reaching each pin in the connector. A properly wired trailer will allow you to verify that all lighting functions (brake lights, turn signals, running lights) work correctly.
Perform periodic inspection of all wires and connections to ensure there is no visible damage or loose connections. The manual does not specify an inspection interval. Check the harness and connectors regularly, especially before towing.
No. The manual states: be sure the harness will not pinch or bind when operating. Route the harness carefully and secure it with the provided cable ties to prevent movement that could damage the wires or connectors.
Part 56003 requires a factory 7-way trailer connector mounted to the hitch or bumper. The manual does not list specific truck models. Contact Curt Manufacturing with your vehicle's year, make, and model to confirm fitment.
Yes, disconnect the negative battery terminal before starting installation (Step 1) and reconnect it after testing (Step 7).
The manual rates the installation difficulty as Easy but does not specify an installation time. Time will vary depending on installer experience, vehicle condition, and available tools.
The manual does not mention drilling or permanent modifications. It references a cutout in the truck bed and a filler plug location, suggesting the truck is pre-prepared for this product. Confirm with Curt Manufacturing whether your truck has these factory features.
Use a test light or connect a properly wired trailer to verify proper function. Test all lighting circuits (brake lights, turn signals, running lights) before reconnecting the battery.
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