Our in-house experts typically reply within one business day.
CURT
Verify Fitment
Select your vehicle to confirm this part fits.
Always the correct part
We know our products
Quality Products
Free Shipping!
Always the correct part
We know our products
Quality Products
Free Shipping!
| Battery-Powered | Yes |
| Converter Type | Circuit Protected, Powered, Potted |
| Electrical System Type | 3W |
| Finish | Blank |
| Material | THERMOPLASTIC RUBBER |
| Mount Type Description | Not Applicable |
| Output Type | 4-Way Flat |
| Side Application Type Description | Not Applicable |
| T-Connector Location | T1,T2 |
| Tail Light Circuits | 7.5 Amps |
| Turn and Brake Circuits | 5.0 Amps |
| Warranty | One-Year Limited Warranty |
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 888-634-9494The 21-23 Ford F-150 Excluding factory receiver or Police Responder CURT 4-way Plug and Play Trailer Wiring (Part #CTW851) fits the following vehicles: 2021-2023 Ford F-150. Always verify your specific year, make, and model before ordering.
The 21-23 Ford F-150 Excluding factory receiver or Police Responder CURT 4-way Plug and Play Trailer Wiring (Part #CTW851) fits 2021-2023 Ford F-150 models. The 2023 model year is the last year covered by this part number. For newer models, check for an updated version.
Yes, the 21-23 Ford F-150 Excluding factory receiver or Police Responder CURT 4-way Plug and Play Trailer Wiring (Part #CTW851) is designed to fit the 2021-2023 Ford F-150.
The 21-23 Ford F-150 Excluding factory receiver or Police Responder CURT 4-way Plug and Play Trailer Wiring (Part #CTW851) Refer to the included instructions for installation details. Basic hand tools are typically all you need.
The Curt 56481 is a powered converter wiring harness that converts vehicle taillight signals to a 4-flat trailer connector. It allows you to connect a trailer with functioning lights to your truck, so the trailer lights operate in sync with your vehicle's brake, turn, and running lights. The system includes a converter box, wiring harness with color-coded wires (yellow for left turn, green for right turn, red for brake, brown for taillight), and a 4-flat connector for the trailer.
The Curt 56481 is designed for trucks and is compatible with 12-volt negative ground electrical systems only. The manual shows wiring locations for trucks (T1–T5) behind taillight housings and rear bumper areas. However, the manual does not specify compatibility by year, make, model, bed length, cab style, or drivetrain. Contact Curt Manufacturing or consult a fitment database to confirm compatibility with your specific vehicle.
No. The Curt 56481 is designed for 12-volt negative ground systems only. Do not use this converter on 24-volt systems or positive ground systems.
You will need: ratchet, drill, 8mm socket, 3/32" drill bit, socket extension, fishwire (or equivalent such as a cut-up wire hanger, stiff wire, rope or string), and a cutting tool. Proper tools will improve installation quality and reduce time required.
The kit includes: a powered converter box, color-coded wiring harness (yellow, green, red, brown, white), a 4-flat connector with dust cover, double-sided tape for mounting the converter box, cable ties (zip ties) for securing wires, a ground screw with ring terminal, a fuse holder with 10-amp fuse, and butt connectors. Refer to the Hardware Photo on page 1 for visual identification.
Yes. You must disconnect the negative battery terminal before beginning installation. Locate the battery in the engine compartment on the passenger side, disconnect the negative terminal, and fasten the wire down and away from the battery. Reconnect the negative terminal only after all other installation steps are complete and before installing the 10-amp fuse.
Yes. You must remove both taillights to access the taillight wiring connectors. Open the tailgate and use an 8mm socket to remove the two bolts securing each taillight in place. Carefully remove each taillight straight back from the vehicle, locate the wiring connectors, and separate them from the taillight housing without damaging the locking tabs. Set the taillights aside in a safe place.
Fishwire is a method to push or pull electrical wire through a blind hole. Make sure the wire is long enough to stick out on the other side. Insert the fishwire through the blind hole and locate it on the other side. Use tape to secure the harness to the fishwire and pull back up. If the fishwire or harness gets hung up, you may need to push back down, wiggle it around, or twist the wire to loosen it. Fishwire can be anything from a cut-up wire hanger, stiff wire, rope, or string depending on what is needed.
1. Drop the fishwire down into the taillight cavity opening on the driver side. 2. From under the vehicle, attach the custom wiring end with the yellow wire to the fishwire and pull up into the taillight cavity. 3. Attach the custom wiring harness to the vehicle taillight harness. 4. Attach the factory harness to the taillight and the T-end in the custom wiring harness. 5. Route the green wire over to the passenger side, zip-tying as needed along the rear bumper. 6. Repeat the process on the passenger side using the green wire.
Locate a flat spot on the vehicle and adhere the black converter box using the provided double-sided tape and/or zip ties. The manual does not specify exact mounting locations, so choose a protected area away from heat sources, moving parts, and moisture.
Locate a grounding point such as an existing screw or bolt in the frame of the vehicle. If no suitable point exists, drill a 3/32" pilot hole. The area must be free from rust, dirt, and paint—use an abrasive pad or paper to remove rust and paint. Secure the white ground wire with the ring terminal on the existing fastener or with the provided ground screw. Before drilling, check for miscellaneous items that may be hidden behind or under any surface to avoid damage and personal injury.
Route the 4-flat along the rear bumper, using cable ties as needed to secure any loose wires. Mount the 4-flat near the receiver tube. Install the provided 4-flat dust cover to help prevent corrosion.
Drilling is required only if you do not have an existing screw or bolt suitable for grounding the white ground wire. You will need to drill a 3/32" pilot hole in the vehicle frame. Before drilling, check for miscellaneous items that may be hidden behind or under any surface to avoid damage and personal injury. The area must be free from rust, dirt, and paint.
Drill a 3/32" pilot hole for the ground screw. The area must be free from rust, dirt, and paint—use an abrasive pad or paper to clean it. Before drilling, check for miscellaneous items that may be hidden behind or under any surface to avoid damage and personal injury.
No permanent modifications are required. The converter box is mounted using double-sided tape and/or zip ties. The only drilling required is a 3/32" pilot hole for the ground wire, which is a minor modification. All other components are routed along existing surfaces (rear bumper, taillight cavities) without cutting, trimming, or welding.
Signal circuits (left and right turn): 5.0 amps per side. Tail/Running circuits: 7.5 amps total. The battery connection must be fuse-protected with a 10-amp maximum fuse. Do not exceed the product rating or the tow vehicle lamp load rating, whichever is lower. Exceeding the product rating can cause loss of warranty, overheating, and potential fire.
Use an 8mm socket to remove the two bolts securing each taillight in place. A socket extension may be helpful depending on the taillight design.
Yellow = Left turn signal. Green = Right turn signal. Red = Brake signal. Brown = Taillight (running light). White = Ground. These color-coded wires connect to the corresponding circuits in your vehicle's taillight harness and the trailer connector.
Route the black 12-gauge power wire from the converter to the vehicle battery location, taking care to avoid pinch points and hot or rotating components. When passing the power wire through sheet metal, use an existing grommet, add a grommet, or use silicone to protect the wire from sharp edges. Connect the power wire to the positive (+) battery terminal using a ring terminal and butt connector. The battery connection must be protected by a 10-amp fuse (installed in the fuse holder after all other steps are complete). Disconnect the negative battery terminal before wiring the power wire.
Use a 10-amp fuse maximum. The battery connection must be fuse-protected with a 10-amp max fuse. Install the fuse after all other installation steps are complete. Exceeding this rating can cause loss of warranty, overheating, and potential fire.
T1: Behind driver side taillight housing. T2: Behind passenger side taillight housing. T3: Behind driver side rear bumper. T4: Behind center of rear bumper fascia. T5: Behind passenger side rear bumper. These locations are where you will find the vehicle's taillight wiring connectors to connect the Curt 56481 harness.
If the converter is used as a powered module for a two-wire system, the red brake wire must be grounded. Consult the converter documentation or contact Curt Manufacturing for specific instructions on two-wire system configuration.
Before drilling, check for miscellaneous items that may be hidden behind or under any surface to avoid damage and personal injury. When passing the power wire through sheet metal, use an existing grommet, add a grommet, or use silicone to protect the wire from sharp edges. Route the power wire to the battery location taking care to avoid pinch points and hot or rotating components. Disconnect the negative battery terminal before wiring the power wire. Do not exceed the product rating or tow vehicle lamp load rating. Secure the power wire to the vehicle chassis using the provided cable ties.
Do not exceed the product rating or the tow vehicle lamp load rating, whichever is lower. The manual does not specify a maximum lamp load rating for the converter itself. Consult your vehicle owner's manual or contact the vehicle manufacturer for your specific tow vehicle lamp load rating.
Once the custom harness is installed, verify that it is functioning by attaching the 4-flat connector to any trailer with functioning lights. The taillights on the vehicle to be towed should function along with the taillights on the vehicle that is powering them. You can also use a test light to verify proper function of each circuit (left turn, right turn, brake, and running lights).
Periodic inspection of all wires and connections should be performed to ensure there is no visible damage or loose connections. Check the 4-flat connector and dust cover regularly to prevent corrosion. Inspect cable ties and mounting tape to ensure all components remain secure.
Yes. Install the provided 4-flat dust cover to help prevent corrosion. The dust cover protects the connector from moisture and environmental damage.
The Curt 56481 is designed for trucks with 12-volt negative ground systems. Confirm compatibility with your specific year, make, and model by contacting Curt Manufacturing or consulting a fitment database, as the manual does not list specific vehicle applications.
You will need: ratchet, drill, 8mm socket, 3/32" drill bit, socket extension, fishwire (or equivalent), and a cutting tool. All required hardware and components are included in the kit.
Yes. Disconnect the negative battery terminal before beginning installation and reconnect it only after all other steps are complete and before installing the 10-amp fuse.
Use a 10-amp fuse maximum. The battery connection must be fuse-protected with a 10-amp max fuse, installed after all other steps are complete.
Yellow = Left turn, Green = Right turn, Red = Brake, Brown = Taillight (running light), White = Ground. These connect to the corresponding circuits in your vehicle's taillight harness.
If the fishwire or harness gets hung up on something, you may have to push back down, wiggle it around, or twist the wire to loosen it from what it is hung up on. Ensure the fishwire is long enough to stick out on both sides before pulling.
Verify that the harness is functioning by attaching the 4-flat connector to a trailer with functioning lights. The taillights on the vehicle to be towed should function along with the taillights on the vehicle powering them. Check all wire connections for damage or loose connections, verify the 10-amp fuse is installed and intact, confirm the ground wire is securely attached to a clean, rust-free frame point, and ensure the power wire is properly connected to the positive battery terminal with a ring terminal.
1 compatible vehicles
| Year | Make & Model | Notes |
|---|---|---|
| 2021 - 2023 | Ford F-150 | Excluding factory receiver or Police Responder |
Total for 2 items:
$539.77$686.70
On Sale Today
Original price was $155.90. Current price is $139.78.You save $16.12 (10%)
Free Shipping
Ships free on all orders
Authorized Dealer
Quick Ship
In stock and ready to ship — order now!
FREE ShippingFREE SHIPPING
Estimated delivery Thu, Aug 13 - Sun, Aug 16
Order before 2 PM EST Monday–Friday for same-day processing
Guaranteed safe & secure checkout
No reviews have been added for this product.
