--- product_id: 77742154 title: "True MODS 4-Way Flat Trailer Light Tester 4-Pin Wiring Circuit Test" brand: "online led store" price: "$15.64" currency: USD in_stock: true reviews_count: 8 category: "Online Led Store" url: https://www.desertcart.us/products/77742154-true-mods-4-way-flat-trailer-light-tester-4-pin store_origin: US region: United States of America --- # Nickel-plated copper terminals for superior conductivity 4-pin flat trailer wiring compatibility Plug-n-play no-tools-needed design True MODS 4-Way Flat Trailer Light Tester 4-Pin Wiring Circuit Test **Brand:** online led store **Price:** $15.64 **Availability:** ✅ In Stock ## Summary > 🚛 Light up your trailer troubleshooting game—fast, foolproof, and fail-safe! ## Quick Answers - **What is this?** True MODS 4-Way Flat Trailer Light Tester 4-Pin Wiring Circuit Test by online led store - **How much does it cost?** $15.64 with free shipping - **Is it available?** Yes, in stock and ready to ship - **Where can I buy it?** [www.desertcart.us](https://www.desertcart.us/products/77742154-true-mods-4-way-flat-trailer-light-tester-4-pin) ## Best For - online led store enthusiasts ## Why This Product - Trusted online led store brand quality - Free international shipping included - Worldwide delivery with tracking - 15-day hassle-free returns ## Key Features - • **Compact & Ready to Go:** Slim two-sided design fits glove box or toolbox for on-the-go troubleshooting. - • **Zero Tools, Zero Hassle:** Plug-n-play simplicity means anyone can test trailer lights in seconds. - • **Built to Brave the Elements:** Weatherproof, corrosion-resistant, and impact tough for years of reliable use. - • **Split & Conquer Wiring Issues:** Isolate faults quickly by testing tow vehicle or trailer side separately. - • **Instant Trailer Light Diagnostics:** Plug inline and get immediate LED feedback—no guesswork, no delays. ## Overview The True Mods 4-Way Flat Trailer Wiring Tester is a compact, durable diagnostic tool featuring nickel-plated copper terminals and a plug-n-play design. It enables quick, tool-free testing of 4-pin trailer light circuits by isolating wiring faults between tow vehicle and trailer. Weather and impact resistant, this tester delivers reliable, on-the-spot LED feedback to save time and prevent electrical wear. ## Description True Mods 4-Way Flat Trailer Wiring Tester [Nickel-Plated Copper Terminals] [Male & Female] [Continuity Test] 4-Pin Trailer Light Wire Circuit Tester: desertcart.com: Tools & Home Improvement Review: True Mods 4-Way Flat Trailer Wiring Tester - The True Mods 4-Way Flat Trailer Wiring Tester is not just a useful tool—it is an absolutely essential piece of equipment for any trailer owner. This compact, clever unit completely changes the way you troubleshoot trailer lighting issues, making what is usually a frustrating process quick and straightforward. The Problem Solver The biggest pain point with trailer wiring is having to constantly hook up and unhook your tow vehicle just to see if a light is working. This tester eliminates that hassle entirely. This unit allows you to diagnose your entire lighting system without ever connecting the trailer to your car or truck. All you need is a simple 12-volt battery and a couple of wires to power the tester. Once connected, you can perform comprehensive checks on: Running Lights Brake Lights Turn Signals (Flashers) Emergency Blinkers Operation and Effectiveness The design is simple and highly effective. By providing power directly to the trailer plug through the tester, you can isolate and test each circuit individually. I was personally able to diagnose and repair my trailer lights quickly thanks to this invaluable tool. Instead of playing the frustrating "guess-and-check" game with the vehicle, I could pinpoint exactly which wire or connection was faulty on the trailer itself. This not only saved me considerable time but also prevented wear and tear on my vehicle's electrical system. Final Verdict If you own a trailer of any kind, the True Mods 4-Way Flat Trailer Wiring Tester is a must-have addition to your toolbox. It is a small investment that pays massive dividends in time and frustration saved. Its ability to turn a complicated diagnostic task into a simple bench test is brilliant. Rating: 5 out of 5 Stars. This tool is a true game-changer for trailer maintenance. Review: Ease of use and good quality. - Love it and use it on my truck and Jeep to make sure all the lights are working. Had one light out and picked up on a bad wire quickly. Good quality also. Highly recommend ## Features - STRAIGHTFORWARD TRAILER LIGHT TESTING - Simply plug the tester inline between the tow vehicle and trailer, turn on the lights and check the easy to read LEDs. - ISOLATE PROBLEMS QUICKLY- By effectively splitting the trailer wiring harness in half, problems can be quickly traced to the tow vehicle side or the trailer side wiring. - NO TOOLS NEEDED - Plug-n-play design means you don't need anything else to effectively test your trailer light harness. - LONG LASTING CONSTRUCTION - Designed to be weather, corrosion, and impact resistant for years of reliable service. - CONVENIENT COMPACT DESIGN -The two-sided design means you can leave it plugged in or store it conveniently in your glove box, door pocket, or tool box. ## Technical Specifications | Specification | Value | |---------------|-------| | ASIN | B07G8Q5LMS | | Best Sellers Rank | #19,574 in Tools & Home Improvement ( See Top 100 in Tools & Home Improvement ) #34 in Circuit Testers | | Brand | ONLINE LED STORE | | Brand Name | ONLINE LED STORE | | Color | Black | | Customer Reviews | 4.7 out of 5 stars 2,547 Reviews | | Item Dimensions | 6.5 x 3.74 x 0.7 inches | | Item dimensions L x W x H | 6.5 x 3.74 x 0.7 inches | | Manufacturer | ONLINE LED STORE | | Measurement Type | Electrical Measurement Device | | Model | 8542039913 | | Power Source | Corded Electric | | Style | Flat | | Style Name | Flat | | UPC | 816165026065 | | Upper Temperature Rating | 60 Degrees Celsius | ## Product Details - **Brand:** ONLINE LED STORE - **Color:** Black - **Item dimensions L x W x H:** 6.5 x 3.74 x 0.7 inches - **Power Source:** Corded Electric - **Style:** Flat ## Images ![True MODS 4-Way Flat Trailer Light Tester 4-Pin Wiring Circuit Test - Image 1](https://m.media-amazon.com/images/I/714csEeqykL.jpg) ## Questions & Answers **Q: Does the testerwork wothout the trailer being attached?** A: Yes. You can utilize the tester to test the tow vehicle side of connection without the trailer attached to it. Hope this helps. **Q: Does it work on bulbs that aren't LED** A: Yes - This is testing your wiring, not your bulbs. The only reason the description mentions LEDs is because the indicator lights on the tester are long lasting LED. **Q: tried this today, when I turn on the left or right directional all the lights light up on the tester? is it supposed to be all lights?** A: Only one LED will light showing left or right or tail lights. Sounds like you have a wiring problem in the vehicle's wiring to the connector. I would check the ground connection for good continuity to the auto frame. An 'open' ground would allow all lights to light as you describe. You could verify that the tester is ok by trying it on another vehicle, too. **Q: Why are all three lights on when connecting the trailer and car? Lights arent working on the trailer and the tester works when only connected to the c** A: it shows there is electric to that poin not thoughtto th blubs on thr trailer ## Customer Reviews ### ⭐⭐⭐⭐⭐ True Mods 4-Way Flat Trailer Wiring Tester *by N***K on October 5, 2025* The True Mods 4-Way Flat Trailer Wiring Tester is not just a useful tool—it is an absolutely essential piece of equipment for any trailer owner. This compact, clever unit completely changes the way you troubleshoot trailer lighting issues, making what is usually a frustrating process quick and straightforward. The Problem Solver The biggest pain point with trailer wiring is having to constantly hook up and unhook your tow vehicle just to see if a light is working. This tester eliminates that hassle entirely. This unit allows you to diagnose your entire lighting system without ever connecting the trailer to your car or truck. All you need is a simple 12-volt battery and a couple of wires to power the tester. Once connected, you can perform comprehensive checks on: Running Lights Brake Lights Turn Signals (Flashers) Emergency Blinkers Operation and Effectiveness The design is simple and highly effective. By providing power directly to the trailer plug through the tester, you can isolate and test each circuit individually. I was personally able to diagnose and repair my trailer lights quickly thanks to this invaluable tool. Instead of playing the frustrating "guess-and-check" game with the vehicle, I could pinpoint exactly which wire or connection was faulty on the trailer itself. This not only saved me considerable time but also prevented wear and tear on my vehicle's electrical system. Final Verdict If you own a trailer of any kind, the True Mods 4-Way Flat Trailer Wiring Tester is a must-have addition to your toolbox. It is a small investment that pays massive dividends in time and frustration saved. Its ability to turn a complicated diagnostic task into a simple bench test is brilliant. Rating: 5 out of 5 Stars. This tool is a true game-changer for trailer maintenance. ### ⭐⭐⭐⭐⭐ Ease of use and good quality. *by P***S on February 10, 2026* Love it and use it on my truck and Jeep to make sure all the lights are working. Had one light out and picked up on a bad wire quickly. Good quality also. Highly recommend ### ⭐⭐⭐⭐⭐ Nice and bright *by O***F on February 28, 2026* This device works well. Currently have it inside the cab of my van so I can see which rear lights are activating. --- ## Why Shop on Desertcart? - 🛒 **Trusted by 1.3+ Million Shoppers** — Serving international shoppers since 2016 - 🌍 **Shop Globally** — Access 737+ million products across 21 categories - 💰 **No Hidden Fees** — All customs, duties, and taxes included in the price - 🔄 **15-Day Free Returns** — Hassle-free returns (30 days for PRO members) - 🔒 **Secure Payments** — Trusted payment options with buyer protection - ⭐ **TrustPilot Rated 4.5/5** — Based on 8,000+ happy customer reviews **Shop now:** [https://www.desertcart.us/products/77742154-true-mods-4-way-flat-trailer-light-tester-4-pin](https://www.desertcart.us/products/77742154-true-mods-4-way-flat-trailer-light-tester-4-pin) --- *Product available on Desertcart United States of America* *Store origin: US* *Last updated: 2026-08-21*