Tekonsha 118720 ModuLite HD 4-Way Flat Wiring Module
Tekonsha 118720 ModuLite HD 4-Way Flat Wiring Module — Product description
The Tekonsha ModuLite HD is a circuit-protected power module that runs your trailer lights off the vehicle battery instead of overloading the tow vehicle's wiring. This 118720 version gives you a 4-way flat connector as a replacement for an OEM-style harness. Clean trailer lighting, with built-in protection for your truck's electronics.
When your tow vehicle didn't come with a factory tow package, wiring trailer lights straight into the vehicle's harness is asking for trouble. That's where the Tekonsha ModuLite HD comes in. It's the heavy-duty power module that takes the load off your vehicle's lighting circuits and runs your trailer lights off the battery instead.
Here's the problem it solves. Trailer bulbs draw current. Splice them into a modern vehicle's wiring and you can overload circuits, trip bulb-out warnings, or in the worst case damage a body control module. The ModuLite HD sits between the two. It reads the low-current signal from your vehicle's lighting, then switches full battery power to the trailer through the 4-way flat connector. Your vehicle's electronics never see the extra draw.
Built-in circuit protection is the other half of the story. If the trailer side shorts out, say a pinched wire or a corroded connector, the module protects itself and your vehicle instead of sending the fault back into the dash wiring. That's the HD difference. It's the tougher version of the standard ModuLite, made for people who tow regularly and want the wiring to just work.
This part, the 118720, is set up as a 4-way flat replacement for an OEM-style wiring harness. You get the standard 4-pole flat plug that fits most small utility trailers, boat trailers, and pop-up campers, the kind that run tail lights, brake lights, and turn signals with no separate brake circuit.
Install is straightforward for anyone comfortable with basic 12-volt work. You're tapping the vehicle's lighting signals, running a fused power lead to the battery, and grounding the module to clean bare metal. Take your time on the ground. That's where most trailer-light gremlins start. Once it's in, you get consistent trailer lighting that doesn't fight with your vehicle's computer.
Who's it for? Anyone towing a light trailer with a vehicle that didn't come tow-ready, or anyone replacing a tired factory harness that's gone flaky. If you've been chasing flickering trailer lights every spring, a circuit-protected module like this is usually the fix. We're an authorized Tekonsha dealer, so you're getting the real part with the full warranty behind it.
Key Features
- Circuit-protected ModuLite HD module isolates the trailer load from your vehicle, so lighting faults don't reach the tow vehicle's electronics
- 4-way flat connector fits standard utility, boat, and pop-up trailers running tail, brake, and turn signals
- Draws trailer lighting power directly from the battery, keeping your vehicle's factory circuits from overloading
- Built-in circuit protection guards against shorts and overloads on the trailer side
- Set up as a 4-way flat replacement for an OEM-style wiring harness
- Tekonsha ModuLite HD build, the heavy-duty version for boaters and haulers who tow often
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 with Circuit Protected ModuLite HD Module |
|---|---|
| Brand | Tekonsha |
| Manufacturer Part Number | 118720 |
| UPC | 016118145359 |
| Trailer Connector | 4-Way Flat |
| Power Module | ModuLite HD |
| Circuit Protection | Built-in |
| Application | Replacement for OEM wiring harness |
Frequently asked questions
What does the ModuLite HD module actually do?
It runs your trailer lights off the vehicle battery instead of splicing them straight into your vehicle's wiring. The module reads the low-current lighting signals from the vehicle, then switches full battery power out to the trailer through the 4-way flat connector, so your vehicle's circuits and computer never see the trailer's load.
What kind of trailer plug does the 118720 use?
A standard 4-way (4-pole) flat connector. That's the common plug for smaller trailers, boat trailers, utility trailers, and pop-up campers that run tail lights, brake lights, and turn signals with no separate electric brake circuit.
Why is it called circuit protected?
The module has built-in protection that trips if the trailer side shorts out or overloads, from a pinched wire or corroded connector for example. It protects itself and your tow vehicle instead of sending the fault back into the vehicle's wiring.
Is this hard to install?
Not for anyone comfortable with basic 12-volt work. You tap the vehicle's lighting signals, run a fused power lead to the battery, and ground the module to clean bare metal. A solid ground is the single most important step.
What does replacement for OEM wiring harness mean?
The 118720 is built to replace a factory-style trailer wiring harness with the ModuLite HD module and a 4-way flat output. It's a good fix if your original harness has gone flaky or you're adding trailer lighting to a vehicle that didn't come tow-ready.
How is the HD different from the standard ModuLite?
HD is the heavier-duty version of the ModuLite module, built for people who tow regularly. Same basic idea of powering trailer lights off the battery, with a tougher build behind it.
