Trailer Wiring & Brake Systems

7-Pin & 4-Pin Connector Diagnosis & Repair

The trailer connector is the most common failure point in any trailer wiring system. Corrosion, bent pins, broken wires at the connector body, and poor ground connections cause intermittent and complete lighting failures. We test each circuit with a proper DVOM — not just a test light — to identify exactly which circuit has failed and where the fault is located.

Running Lights, Brake Lights & Turn Signals

If your trailer lights aren’t working correctly, the fault can be in the connector, the wiring harness, a ground connection, or the lights themselves. We trace each circuit from the connector to the light to find the actual break rather than replacing components until something works.

Wiring Harness Inspection & Repair

Trailer wiring harnesses run the length of the trailer and are exposed to road debris, moisture, UV, and physical damage over years of use. Chafed insulation, corroded splices, and broken conductors are found by systematic circuit tracing — not by visual inspection alone. We locate the fault, repair it correctly, and protect the repair against future corrosion.

Connector Upgrades & Adapters

If your tow vehicle and trailer connectors don’t match, we install permanent adapters or upgrade trailer connectors to match your tow vehicle. Clean, properly secured installations — not loose adapters hanging off the connector.

Tow Vehicle Wiring

Tow vehicle trailer wiring that’s failed, corroded, or was never properly installed is within scope. We install or repair the tow vehicle side including proper fusing, ground connections, and brake controller wiring.

Brake Controller Calibration & Diagnosis

A controller that’s not calibrated correctly either under-brakes — leaving the trailer pushing the tow vehicle — or over-brakes, causing wheel lockup and instability. We verify controller output signal, calibrate gain settings for your specific trailer and load, and confirm proper brake engagement during a test stop.

Electric Brake Magnet Testing & Replacement

Electric trailer brakes use an electromagnet inside each brake drum to actuate the brake shoes. Magnets wear out, burn out, and develop open or shorted windings that reduce or eliminate braking force. We measure magnet resistance and current draw at each wheel to identify failed or degraded magnets and replace them on-site.

Brake Wiring Diagnosis

The wiring from the 7-pin connector to each brake magnet is subject to the same damage as any trailer wiring. We trace brake circuit continuity and verify correct voltage and current delivery at each magnet under controller output.

Breakaway System Testing

The breakaway system is a battery-powered emergency brake actuator that engages all trailer brakes automatically if the trailer separates from the tow vehicle. Most trailer owners never test it. We verify breakaway battery charge, test switch activation, and confirm brake engagement when the system is triggered. A dead battery or failed switch provides zero protection when it’s needed most.

Brake Adjustment

Electric trailer brakes require periodic adjustment as brake shoes wear. Improperly adjusted brakes reduce stopping effectiveness and accelerate magnet wear. We adjust brake shoe clearance at each wheel for correct operation.