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Curt 55329 T-One T-Connector Trailer Wiring Harness - 4-Flat Plug-and-Play

CURT 55329 T-One T-Connector trailer wiring harness with 4-flat plug, plug-and-play no-splice installation for tow vehicles
 
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: $38.17
Part Number: 55329
Manufacturer: Curt MFG

Quantity in Stock :38

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CURT Manufacturing4-Flat ConnectorNo-Splice InstallCURT 55329 T-One T-Connector Trailer Wiring Harness

Stop wrestling with spliced wires and electrical tape. The CURT 55329 T-One connector plugs directly into your vehicle's factory tail light harness, delivering a clean, reliable 4-flat trailer wiring hookup with zero cutting or splicing required. Get your trailer's running lights, brake lights, and turn signals working the right way -- the first time.

Plug-and-Play Trailer Wiring -- Done Right

The CURT 55329 is part of CURT's T-One connector family, one of the most widely used vehicle-specific trailer wiring solutions in the aftermarket. Unlike universal wiring kits that require you to tap into and splice existing wires, the T-One design uses a pass-through connector that plugs in between your factory tail light harness and the tail light itself. Your factory wiring stays completely intact.

The result is a weatherproof, factory-looking installation that preserves your vehicle's original electrical system and won't void factory warranties related to wiring modifications. CURT engineers each T-One harness to match the specific plug-and-socket configuration of the target vehicle, so the connectors simply click in with no guesswork.

No Cutting or Splicing

Plugs directly into the factory tail light socket. Your stock wiring is never touched or modified.

4-Flat Output

Standard 4-pin flat connector delivers running lights, left turn/brake, right turn/brake, and ground to your trailer.

Vehicle-Specific Fit

Engineered to match factory harness connectors on specific tow vehicles -- no universal adapter fumbling.

Weatherproof Contacts

Molded connector body and sealed contacts resist moisture, road grime, and corrosion common on RV tow vehicles.

What the 4-Flat Connector Supports

The 4-flat (also called 4-pin flat) is the standard light connector for most small-to-mid-size trailers, including:

  • Utility and cargo trailers
  • Boat trailers
  • Small travel trailers and teardrop campers
  • Motorcycle and ATV trailers
  • Landscape and equipment trailers

The four circuits carried by this connector are: TM (tail/running lights), LT (left turn and brake), RT (right turn and brake), and GD (ground). If your trailer also needs electric brakes or a 12V aux circuit, you would need a 5-flat or 7-way connector -- but for light-duty towing without electric brakes, the 4-flat is the correct and most common choice.

Clean Install, No Converter Needed: Because the T-One taps the vehicle's existing turn/brake and running light circuits, there is no need for a separate converter module on most modern vehicles. CURT does include a converter/module where the target vehicle's wiring requires it.

CURT T-One Series Overview

CURT manufactures dozens of T-One connectors, each coded to a specific vehicle application. Part number 55329 is a vehicle-specific unit within this series. Always verify the vehicle fitment chart (by year, make, model, and trim/package) before ordering, as two trucks from the same model year can have different tail light harness configurations depending on the factory package installed.

Fitment Tip: CURT's T-One connectors are keyed by vehicle application. Confirm your exact year, make, model, and whether your vehicle has a factory tow package before ordering. A factory tow package often means a 7-way is already provisioned at the hitch -- the T-One in that case may still be needed for a second trailer plug at the bumper or for a specific body style variant.

Installation Overview

Installation typically takes 15-30 minutes with basic hand tools and requires no electrical knowledge beyond plugging in connectors:

  • Access the tail light assembly on each side of the vehicle (usually a few screws or push-pins)
  • Unplug the factory tail light connector
  • Plug the T-One harness in-line between the factory harness and the tail light
  • Route the 4-flat connector to the hitch area and secure with provided hardware or zip ties
  • Test all circuits with a trailer or test light before towing
Maintenance Tip: Apply dielectric grease to the 4-flat connector contacts once a year, especially if you tow in wet or salty conditions. This prevents oxidation that causes intermittent light failures -- the most common trailer lighting complaint.
Circuit Load: The T-One passes through your factory tail light circuits. Do not exceed the current draw of your vehicle's factory tail light fuses when connecting trailer lights. LED trailer lights draw far less current than incandescent and are strongly recommended to keep total circuit load well within spec.

Package Specifications

ManufacturerCURT Manufacturing
Part Number55329
UPC612314553297
Package Weight0.53 lbs
Package Dimensions9.0 in x 4.0 in x 3.0 in

Connector Specifications

Connector TypeT-One (pass-through, no-splice)
Output Plug4-flat (4-pin flat trailer connector)
Circuits ProvidedRunning/tail, left turn/brake, right turn/brake, ground
Install MethodPlug-and-play, in-line with factory tail light harness
Converter RequiredIncluded where vehicle wiring requires it

Electrical Details

System Voltage12V DC
Compatible Trailer LightsIncandescent and LED
Recommended Trailer LightsLED (lower current draw, longer life)

What's in the Box

Wiring HarnessVehicle-specific T-One connector assembly
4-Flat PlugYes, included on harness
HardwareMounting clips or zip ties for routing (varies by kit)
InstructionsYes, vehicle-specific installation sheet included

Common Towing Applications

Utility TrailersYes
Boat TrailersYes
Small Travel TrailersYes (no electric brakes)
Teardrop CampersYes
Trailers with Electric BrakesNo -- requires 5-flat or 7-way
Important Information
  • Verify vehicle fitment by year, make, model, and trim before ordering. This connector is vehicle-specific and will not fit all vehicles.
  • This connector supports 4-flat trailer wiring only. It does not provide a brake controller circuit or 12V aux power. Trailers requiring electric brakes need a 7-way connection.
  • Do not exceed the current rating of your vehicle's tail light fuses. Overloading the circuit can blow fuses or damage factory wiring.
  • Ensure all connections are fully seated and secured before towing. Loose connections cause intermittent light failure, which is a safety and legal issue.
  • This product does not include a trailer ball, ball mount, or hitch receiver. It is a wiring harness only.
  • If your vehicle has a factory integrated trailer brake controller or trailer wiring package, consult CURT's fitment guide to confirm this T-One connector is still required for your specific setup.


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