Tekonsha 118400 4-Way Flat OEM Wiring Harness
Tekonsha 118400 4-Way Flat OEM Wiring Harness — Product description
Chased a dead trailer light and found the factory harness crushed or corroded? The Tekonsha 118400 is the 4-way flat replacement for your vehicle's OEM tow-package wiring. It plugs into the factory connection and gives you a clean, standard 4-flat plug for the trailer.
The Tekonsha 118400 replaces the 4-way flat wiring harness that came with your vehicle's factory tow package. If the original connector got crushed backing into a hitch, corroded from road salt, or just went intermittent on you, this is the part that gets your trailer lights working again without a full rewire.
It's a T-One style connector assembly, which means it's built to plug into your vehicle's existing tow-package connection instead of tapping and splicing into the taillight wiring. You get the factory-style connection on one end and a standard 4-way flat trailer plug on the other. That 4-flat is the connector you'll find on most single-axle boat trailers, small utility trailers, and pop-up campers, so whatever you're pulling behind a light-duty setup, it'll match up.
The 4-way flat carries the circuits a basic trailer needs: running and tail lights, left turn and brake, right turn and brake, plus a ground. No electric-brake output, no reverse, no 12-volt charge line. It's the straightforward lighting connection, and for a lot of us trailering a single-axle rig, that's exactly all you want.
Install is about as simple as trailer wiring gets. Locate the factory tow connector, unplug the damaged harness, plug the 118400 in, and route the 4-flat back to where you can reach it. No cutting, no butt connectors, no chasing a short through the vehicle harness. Hit the terminals with a little dielectric grease before you seat them and you'll save yourself a corroded connection down the road.
Tekonsha has been building trailer wiring and brake control gear for decades, and their connectors are the ones a lot of us reach for first when a factory harness gives up. If you're not sure your vehicle came with a factory tow-package connector, or you're not seeing the matching plug near the bumper, send us your year, make, and model and we'll confirm before you order.
Key Features
- 4-way flat replacement for a vehicle's factory (OEM) tow-package wiring harness
- T-One style connector assembly plugs into the existing factory tow connection, no splicing into the taillight wiring
- Standard 4-way flat trailer plug fits most single-axle boat, utility, and camper trailers
- Carries running and tail, left turn-brake, right turn-brake, and ground circuits
- Direct-replacement design restores factory-style trailer lighting after a damaged or corroded harness
- Built by Tekonsha, a longtime name in trailer wiring and tow electrical
Why Buy from NVN Marine
- Authorized Tekonsha reseller, full manufacturer warranty
- NMEA member and ABYC certified, advice from real boat techs
- Same-day shipping before 3 PM ET on in-stock items
- NY headquarters and Fort Lauderdale flagship retail store
Technical specifications
| Title | 4-Way Flat Replacement For OEM Wiring Harness |
|---|---|
| Brand | Tekonsha |
| Manufacturer Part Number | 118400 |
| UPC | 016118058420 |
| Connector Type | 4-Way Flat |
| Number of Poles | 4 |
| Assembly Type | T-One Connector Assembly |
| Application | Replacement for OEM (factory) tow-package wiring harness |
| Vehicle-Side Connection | Plug-in to factory tow connector, no splicing |
Frequently asked questions
What does the Tekonsha 118400 replace?
It replaces the 4-way flat wiring harness that came with your vehicle's factory tow package. If the original got crushed, corroded, or stopped passing signal, this brings your trailer lights back without rewiring the vehicle.
Do I have to splice into my taillight wiring?
No. This is a T-One style connector assembly, so it plugs into the factory tow connection your vehicle already has. No cutting and no tapping into the taillight harness.
What trailers will the 4-way flat plug fit?
The 4-flat is the standard connector on most single-axle boat trailers, small utility trailers, and pop-up campers. If your trailer has a 4-flat, this matches it.
Does this carry trailer brakes or a charge line?
No. A 4-way flat handles lighting only: running and tail, left turn and brake, right turn and brake, and ground. There's no electric-brake output or 12-volt charge wire on a 4-flat.
How do I know if my vehicle has a factory tow connector?
Look for a capped connector tucked up near the rear bumper or in the spare-tire area. If you're not sure, send us your year, make, and model and we'll confirm this is the right harness before you order.
Any tips for a lasting connection?
Yeah. Hit the terminals with dielectric grease before you seat the plug, and route the 4-flat where it won't drag or sit in standing water. That's most of what kills trailer connectors.
