Tekonsha 118890 T-One ModuLite HD 4-Way Flat Harness
Tekonsha 118890 T-One ModuLite HD 4-Way Flat Harness — Product description
The Tekonsha 118890 is a complete T-One tow-wiring package that plugs a 4-way flat trailer connector onto your vehicle without cutting a single factory wire. The circuit-protected ModuLite HD module does the electrical heavy lifting, pulling power straight from the battery for a clean, dedicated trailer feed.
The Tekonsha 118890 is a complete T-One wiring package that gets a 4-way flat trailer connector onto your tow vehicle without cutting a single factory wire. The T-One side plugs straight into your vehicle's existing harness, and the circuit-protected ModuLite HD module handles the electrical work.
Here's what the ModuLite HD part actually means. Instead of tapping trailer power off your taillight circuit the way a cheap converter does, this module pulls power directly from the vehicle battery. Your trailer lights get their own dedicated feed, so you're not overloading the factory lighting circuit or confusing a modern vehicle's bulb-out monitoring. The HD is the higher-capacity version, built for the extra draw of bigger trailers running more lights.
Circuit protected means exactly that. The module has built-in protection that shields your vehicle's wiring and control module if the trailer side ever shorts out. A nicked wire, a corroded connector, a bad ground on the trailer. The protection trips instead of frying something expensive under the dash. That's the whole reason to run a powered converter instead of a simple splice-in tap.
Install is genuinely plug-and-play on the vehicle end. Find the factory connector, unplug it, drop the T-One in between, and plug it back together. Most folks have it done in about ten minutes with no tools beyond their hands. The 4-way flat then handles the four basic trailer functions: running and tail lights, left turn, right turn, and stop, sharing the turn and brake signals the way a 4-way does.
One thing to get right before you order. Tekonsha builds the T-One connector to match a specific vehicle's factory harness, and the 118-series part numbers each fit different year, make, and model combinations. Check that 118890 is the correct number for your exact vehicle before you buy. If you're not sure, send us your year, make, and model and we'll confirm it fits.
Key Features
- Circuit-protected ModuLite HD module draws power straight from the vehicle battery, not the taillight circuit
- Vehicle-specific T-One connector plugs into the factory harness with no cutting or splicing
- 4-way flat output powers trailer running lights, left and right turn, and stop
- Built-in circuit protection trips on a trailer short to protect the vehicle's wiring and control module
- HD-rated converter handles the higher current draw of larger trailers
- Weatherproof connector and module hold up to road spray and the elements
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 | T-One Connector With Circuit Protected ModuLite HD Module; With 4-Way Flat |
|---|---|
| Brand | Tekonsha |
| Manufacturer Part Number | 118890 |
| UPC | 016118167542 |
| Connector Type | 4-Way Flat |
| Converter Module | Circuit Protected ModuLite HD |
| Wiring Type | Vehicle-specific plug-in T-connector |
| Power Source | Powered converter, draws from vehicle battery |
| Circuit Protection | Integrated, protects vehicle wiring on trailer fault |
| Trailer Output | Tail/running, left turn, right turn, stop |
Frequently asked questions
What does the ModuLite HD module actually do?
It's a powered converter. It pulls power directly from your vehicle's battery to run the trailer lights instead of stealing it from the taillight circuit. That gives the trailer a clean, dedicated feed and keeps you from overloading the factory lighting. The HD version is built for the higher current of larger trailers.
Do I have to cut or splice my vehicle's wiring?
No. The T-One connector plugs right into your vehicle's existing factory harness. You unplug the factory connector, put the T-One in line, and plug it back together. Nothing gets cut.
What does circuit protected mean here?
The module has built-in protection that trips if the trailer wiring shorts out. So a bad ground or a nicked wire on the trailer won't send a fault back into your vehicle's wiring or control module. It protects the expensive stuff.
Will this fit my vehicle?
The T-One is built for a specific factory harness, and each 118-series part number matches different vehicles. Confirm that 118890 is the right number for your exact year, make, and model before ordering. Send us those details and we'll check it for you.
What's the 4-way flat connector for?
It's the standard 4-pin flat trailer plug. It carries the four basic functions: running lights, left turn, right turn, and stop. It's what most utility trailers, small boat trailers, and light-duty trailers use.
Does it draw power from my battery?
Yes. That's the point of a powered converter. It runs a dedicated feed from the battery so your trailer lights aren't loading down the vehicle's own lighting circuit.
