Know Your Equipment.
Fix It Right the First Time.
In-depth guides written by the team at AAA Trailer — people who work on trailers every day.
KTI Hydraulics
12 GuidesKTI DC26 Gravity Down Too Slow — How to Adjust the Flow Control Valve
Locating the needle valve, which direction to turn it, and 8 other root causes when the valve alone isn't the issue.
What Kind of KTI Pump Do I Have? Identify by Remote Type
Count your buttons, read the labels, and check the pump ports. The complete decision tree for every KTI remote configuration.
How to Install the KTI KWR-005 Wireless Bluetooth Controller
Mount location, antenna placement, wiring to battery, connecting to pump — complete step-by-step from KTI's official installation manual.
How to Pair a Replacement Key Fob to Your KTI KWR Wireless Controller
3-second pairing procedure, adding multiple fobs, clearing memory, and re-pairing the BluetoothKTI phone app.
Which KTI KWR Wireless Controller Do I Need?
KWR-005 vs 006 vs 007 vs 008 — the complete compatibility chart based on your existing wired remote and pump circuit type.
Brakes & Axles
11 GuidesSelf-Adjusting vs. Dexter Nev-R-Adjust Electric Trailer Brakes — What's the Difference?
How each type works, how to identify which you have, side-by-side maintenance comparison, initial adjustment procedure, and which is better for your application.
How to Manually Adjust Electric Trailer Brakes — Star Wheel Procedure
When to adjust, which direction to turn on each side, how much drag to set, and why getting it wrong causes heat damage. Per Dexter's official service manual.
How to Diagnose a Bad Electric Trailer Brake Magnet — Test and Replace
Resistance specs for 7", 10", and 12" magnets, the screwdriver field test, short-to-housing test, symptoms table, and complete replacement procedure.
Wiring & Lights
6 GuidesTrailer Lights Not Working — Complete Diagnostic Guide
The #1 most reported trailer problem. Symptom-to-cause table for every failure mode: no lights, one side out, running lights but no brakes, flickering, blown fuses — plus the ground rule that fixes most issues.
Running Lights Work But Brake and Turn Signals Don't
Why these are separate circuits, how to test each pin, which fuse to check, and why a marginal ground causes this exact symptom pattern.
4-Pin vs. 7-Pin Trailer Connector — Which Do You Have?
What each pin does, when you need a 7-pin vs. 4-pin, adapter limitations, and why you can't tow a braked trailer safely with a 4-pin adapter.
How to Replace Your Trailer Wiring Harness — Step-by-Step
When to replace vs. repair, 8-step installation process, the dedicated ground wire upgrade that eliminates recurring failures, and heat-shrink vs. crimp connections.
Converting Trailer Lights to LED — What You Need to Know
Why LED exposes ground problems that incandescent masked, how to address hyperflash, drop-in vs. full rewire, and what to look for in quality sealed LED fixtures.
7-Pin Trailer Connector Wiring Diagram — Every Pin, Both Standards
Complete pin reference for SAE and RV standards, inline diagram, wire gauge chart, and a troubleshooting table for every common wiring problem.
Tires & Wheels
4 GuidesST vs. LT Trailer Tires — Which Do You Actually Need?
Why ST tires are engineered specifically for trailer axles, how they differ from LT tires in sidewall stiffness and load capacity, and the one exception where LT may be appropriate.
How to Read a Trailer Tire Sidewall — Every Number and Letter Explained
Decode ST205/75R15: width, aspect ratio, construction, rim diameter, load range, speed rating, and how to find the DOT manufacture date.
Why Trailer Tires Age Out Before They Wear Out — The 6-Year Rule
How to find the DOT date code, what happens internally as tires age, when to replace regardless of tread depth, and storage tips to slow aging.
Proper Trailer Tire Inflation — Why It's Different from Your Truck Tires
Always inflate to max cold PSI on the sidewall, how to check correctly, typical PSI by load range, and why under-inflation is the #1 cause of trailer tire failure.
Couplers & Hitches
3 GuidesTrailer Hitch Ball Sizes — 1-7/8" vs 2" vs 2-5/16": Which Do You Need?
Where the size is stamped on your coupler, why wrong ball size looks like it works until it doesn't, real-world incident examples, and a trailer-type quick reference chart.
Trailer Brakes Only Work on Manual Override — Why and How to Fix It
Why manual override proves the brakes are fine, how brake controllers detect stopping, the 5 most common causes in order, and a quick diagnostic checklist.
Trailer Coupler Won't Latch — Causes and Fixes
Wrong ball size, coupler not fully seated, adjustment nut off spec, or corrosion. Includes the "lift 1/4 inch" trick that solves most latch problems, how to adjust the tension nut, and when to replace the whole coupler.
Axle & Suspension
4 GuidesHow to Identify Your Trailer Axle — Capacity, Bolt Pattern, Bearings, and Measurements
Four methods to identify your axle: the label, bolt pattern chart, bearing number table, and tube diameter. Hub face and spring center measurement guide for replacement orders.
Trailer Leaf Spring Identification, Measurements, and Replacement Guide
How to measure springs, double eye vs. slipper, capacity by axle size, signs of failure, and why bushings and shackle bolts fail first.
How to Measure a Trailer Leaf Spring — 6 Measurements to Find the Right Replacement
Eye-to-eye length, leaf count, width, eye type, center bolt hole, and capacity stamp — a printable worksheet plus an in-stock spring reference table matched to axle sizes.
Tongue Jack Won't Crank — How to Free a Seized Trailer Jack
How to tell a seized screw from a broken one, penetrating oil technique, when a drill is faster than a wrench, disassembly steps, and how to prevent future seizure.
Dump Trailer
2 GuidesDump Trailer Won't Lift — Battery, Connections, and Pump Diagnostic
The #1 cause is a weak battery — how to test correctly with a load tester, the solenoid screwdriver test, fluid checks, and battery sizing by pump model.
Dump Trailer Battery Guide — Size, Charging, Testing, and Replacement
Why 12.4V at rest doesn't mean the battery is good, how the 7-pin charges it, Group 27 vs. 31 sizing, and the trickle-charger rule for seasonal storage.
Towing Fundamentals
5 GuidesTrailer Tongue Weight — What It Is, the 10–15% Rule, and How to Measure It
The formula, a by-weight lookup table, three measurement methods, and why exceeding payload is the real risk most towers don't know about.
Towing Capacity vs. Payload vs. GVWR — The Three Numbers Every Trailer Owner Must Understand
Why payload is usually the binding constraint before towing capacity, how to calculate your actual safe trailer weight, and a worked example with an F-150.
Trailer Sway — Causes, Prevention, and What to Do If It Happens
What to do if your trailer is swaying right now, the 6 causes in order of frequency, and how the 60/40 loading rule prevents it before it starts.
How to Load a Trailer Correctly — The 60/40 Rule, Weight Distribution, and Tie-Downs
Step-by-step loading procedure, the 60/40 rule explained with the physics, loading by trailer type, and why the GVWR is a hard limit.
Trailer Lug Nut Torque Specifications and Tightening Procedure
Official torque values from Dexter and Lippert service manuals for 1/2" and 9/16" studs, the 3-stage star-pattern procedure, and the re-torque rule most people skip.
Can't Find the Answer? Call the Counter.
We've been in business for over 20 years. Call us and we'll diagnose it over the phone — and ship the part same-day if it's in stock.
