FitsMyTruckWhat fits your pickup, by truck and bed

By the FitsMyTruck team. Every figure in this guide comes from a maker, automaker or standards document named at the end, and the guide is reviewed before it goes up. How we check what fits.

Trailer wiring connectors by type and circuit

A 4-way flat plug carries taillights, left and right turn and ground. CURT's 5-way adds a reverse circuit. The 6-way round and 7-way plugs add the blue electric brake wire and 12 volt power, which a brake controller needs. Plug-in T-connector harnesses fit a vehicle without splicing, and several trucks ship with a 7-pin and 4-pin connector from the factory.

Connectors and circuits

CURT's wiring page lists the trailer-side functions below. Ground is white on every plug. CURT's Understanding Towing guide also names the plug each trailer type commonly uses.

ConnectorCircuits listed by CURTCommon trailer use per CURT
4-way flatTaillights, left turn and brake, right turn and brake, groundUtility trailers, boat trailers without surge brakes
5-way flatThe 4-way set plus reverse lightsBoat trailers with surge brakes
6-way roundThe 4-way set plus electric brakes and +12 voltGooseneck trailers
7-way RV bladeTaillights, left turn and brake, right turn and brake, electric brakes, +12 volt, reverse lights, groundCamper and 5th wheel trailers
7-way roundThe 4-way set plus electric brakes, reverse lights and auxiliary powerNot stated

CURT lists two color layouts for the 7-way RV blade, a traditional one and an SAE J2863 one, and the wire colors differ between them. Test each pin rather than trusting color. When the truck and trailer plugs differ, CURT's adapter chart pairs each vehicle plug with each trailer plug, for example a 4-way flat to 7-way RV blade adapter.

T-connector, splice or converter

CURT describes a custom wiring harness, or T-connector, as vehicle-specific and plugged in with no splicing. Harnesses usually need two or more connection points, such as the taillight assembly. A connector uses one plug into a factory socket. Taillight converters splice into the vehicle wiring and are the fallback when no custom harness exists. CURT lists 3-to-2 converters for three-wire systems and PWM converters for vehicles that carry stop, turn and tail on one wire. The same page says plugs and sockets use from two to seven wires.

What trucks ship with

Maker documents state what each truck carries from the factory.

Maker documentWiring statement
Toyota, 2024 Tacoma e-brochureSR trim: Class-IV towing hitch with 7-pin/4-pin connector, standard on Double Cab and available on XtraCab; other trims list it as equipment or in the Towing Package
Toyota, 2025 Tundra e-brochureClass-IV towing hitch receiver and wiring harness with 7-pin/4-pin connector
Honda, 2025 Ridgeline specificationsIntegrated Class III trailer hitch with 7-pin connector, standard on all four trims
Nissan, 2025 Frontier press kitTrailer hitch with wiring harness in the SV and PRO convenience packages
Ram, 2016 Ram 1500 e-brochureAll Ram 1500 models provide a 4- and 7-pin connector

None of these documents says whether the 7-pin is the blade or round style. Ford and Chevrolet wiring is not covered here. CURT's page for part 13393 lists a 10 ft extension harness, related product, that adds a 7-way RV blade to the truck bed.

What a brake controller needs

CURT states that a trailer with electric brakes needs a controller, and that the blue wire carries the electric brake circuit on 6-way, 7-way and RV blade plugs. CURT's controllers plug into the 7-way RV blade connection or its harness. Its Discovery NEXT and TriFlex NEXT units manage 2 to 8 trailer brakes (1 to 4 axles), and the Venturer NEXT manages 2 to 6 brakes (1 to 3 axles). Toyota's brochure describes its integrated controller as working with a trailer that has an electric braking system. CURT's list for a 4-way flat plug has no brake wire. For the load side of towing, see tongue weight basics, and for the hitch itself hitch classes explained.

The vehicle's door-jamb sticker, owner's manual and the hitch maker's labels govern. A rating shown here is the maker's published figure, not a guarantee for a specific truck.

Use it with

The hitch tables list the wiring connector per hitch. Pair them with hitch receiver sizes when choosing a hitch and harness together.

Sources

Products named above

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