CURT 3-to-2 Wire Tail Light Converter 58240 — Non-Powered Splice-In for Incandescent Lights, Interior Mount

The CURT 58240 is a non-powered splice-in tail light converter that transforms a vehicle’s 3-wire taillight circuit into a 2-wire trailer output for safe, reliable towing (not for LED systems).

If your vehicle lacks a compatible trailer connector or a vehicle-specific harness, a taillight converter like the CURT 58240 provides a practical way to create a trailer wiring connection by splicing directly into the factory taillight wires. Designed for situations such as dinghy towing or when a custom plug-in harness isn't available, this unit simplifies wiring by reducing three circuits to a standard two-wire output. It’s built for interior mounting and intended for use with conventional incandescent bulbs—do not use it with LED lighting systems.

How does this converter create a trailer connection?

The CURT 58240 taps into your vehicle’s taillight wiring and combines the necessary signals into a 2-wire output that feeds a trailer connector or a 4-way flat socket. It reduces the number of conductors while keeping the signal and taillight circuits functionally separate enough for common towing needs. Installation requires splicing the blunt-cut, color-coded wires to the vehicle harness inside the body or trunk area.

• Splice-in design connects directly to factory taillight wires
• Converts vehicle 3-wire system into a 2-wire trailer output
• Blunt-cut, color-coded leads speed up identification and hookup
• Interior mount only to protect from moisture and road debris

Will this work with my vehicle’s lighting and trailer setup?

The converter is intended for vehicles with standard incandescent taillights and for trailers that accept a 2-wire signal. It supplies separate circuits for the signal and taillight functions at modest amperage levels—suitable for many small trailers and dinghy towing applications. If your vehicle has LED lighting or your trailer requires dedicated powered circuits, choose a compatible powered converter or a vehicle-specific harness instead.

• Not compatible with LED-equipped vehicles or trailers
• Provides 2.1 amps for signal circuit and 5.0 amps for taillight circuit
• Good for small trailers and non-powered dinghy setups
• Can be spliced to a 4-way flat socket for easy trailer hookup

How difficult is installation and what tools or materials are needed?

Installation is straightforward for anyone comfortable with basic automotive wiring and splicing. The unit ships ready-to-install with blunt-cut, color-coded wires; you'll need wire strippers, crimps or solder, and heat-shrink or insulated connectors. Because it mounts inside the vehicle, plan routing and secure the converter away from moving parts and moisture.

• Requires basic wiring tools: strippers, crimpers or soldering iron
• Uses color-coded leads to match vehicle taillight circuits quickly
• Mount inside the vehicle, secure away from heat and pinch points
• No heavy-duty flasher or battery tap needed for normal operation

What are the electrical limits and safety considerations?

The CURT 58240 is a passive, non-powered converter with modest current ratings: 2.1 amps for the turn signal circuit and 5.0 amps for the taillight circuit. It’s designed to handle typical incandescent lamp loads but not the lower-draw characteristics of LEDs. Proper mounting and protected splices help prevent corrosion and intermittent faults during towing.

• Rated 2.1A for signals and 5.0A for taillights—match to lamp loads
• Not intended for LED lighting—use a powered converter for LEDs
• Keep splices sealed and mount interior to avoid moisture exposure
• Do not alter ratings by adding additional loads beyond specifications

Who this is for: The CURT 58240 suits owners who need a reliable, low-complexity solution to create a trailer wiring connection when a vehicle-specific plug-in harness is unavailable and incandescent lighting is used. It’s ideal for DIYers converting three-wire factory taillight systems to a two-wire trailer output for small trailers, dinghy towing, or when adding a simple 4-way flat socket—provided the vehicle doesn’t use LED tail lamps.