A 6-pin trailer plug handles tail lights, turn signals, brake lights, electric brakes, and 12V power — but the pin layout varies by connector type.
Wiring a 6-pin trailer plug adds electric brakes and 12V auxiliary power to the lighting circuits your four-pin connector already handled. The catch: there is no single universal standard for these connectors. Shapes, pin arrangements, and color codes differ between manufacturers, which makes the first step — identifying your specific plug’s layout — the most important one you’ll take. Whether you’re replacing a damaged plug or wiring a new trailer from scratch, the job comes down to matching each wire to the right terminal, testing every circuit, and sealing everything against the elements.
What Wire Colors Go Where on a 6-Pin Plug?
A 6-pin trailer connector carries six separate circuits. The wire colors below are the most common assignments, but they are not guaranteed to match every plug. Always verify against the pinout diagram that came with your specific connector before cutting or crimping.
| Wire Color | Function | Notes |
|---|---|---|
| White | Ground / earth return | Required for all circuits; must be solid |
| Brown | Tail, running, park, clearance, side-marker lights | |
| Yellow | Left turn / left stop-and-turn | |
| Green | Right turn / right stop-and-turn | |
| Blue | Electric brakes / brake controller output | Check brake controller compatibility |
| Black or Red | 12V auxiliary / battery hot / accessory power | Fused supply recommended |
Different manufacturers assign these functions to different pin positions. Narva’s 6-pin small round plug places earth return on pin 6 and service brakes on pin 5. CURT’s 6-pin wiring guide keeps Brown for taillights, Blue for electric brakes, and Black for +12V auxiliary. Croft’s diagram shows ground as black or white and auxiliary as red. The exact layout you need depends entirely on the plug in your hand — there is no shortcut around this step.
How to Wire a 6-Pin Trailer Plug Step by Step
Wiring a 6-pin plug is straightforward if you work through the steps in order. Start by identifying the connector family — 6-way round plugs differ from other 6-pin formats — and locate the exact pinout diagram from the manufacturer.
Strip each wire end carefully, exposing about 1/4 to 1/2 inch of bare conductor — enough for a solid grip without exposed wire past the terminal. Match each wire to the correct terminal according to the plug’s pin diagram, not by color alone. Secure every connection using crimp connectors, terminal screws, or ring terminals depending on your plug’s design. Insulate each splice with electrical tape or heat shrink tubing to keep moisture out, then test all functions: tail lights, turn signals, brake lights, electric brakes, and auxiliary power. If any circuit fails, a loose ground or a swapped left-right pair is the first thing to check.
If you need a replacement plug or a pre-wired assembly, top-rated 6-pin trailer plug options save the guesswork by showing tested designs with reliable pin layouts.
Common Wiring Mistakes to Avoid
Assuming a universal standard. No two manufacturers pin a 6-pin plug the same way, and the color codes don’t always match either. Always use the diagram for your exact model, never a generic one from memory.
Confusing electric brakes with stop lamps. Blue typically carries the brake controller output, but some diagrams label that circuit differently or assign it to a different pin. Confirm the brake circuit before connecting.
Reversing left and right turn wires. Yellow and green are easy to swap, and the mistake is invisible until you test. A quick turn-signal check catches this before the trailer is on the road.
Poor ground connection. The white ground wire needs a clean, firm connection on both the vehicle frame and the trailer frame. A loose or corroded ground causes flickering lights and intermittent brake problems that are hard to diagnose later.
Unsealed connections. Moisture is the leading cause of trailer wiring failure. Heat shrink tubing or quality electrical tape on every splice keeps corrosion from ruining a job before its first season.
FAQs
What gauge wire should I use for a 6-pin trailer plug?
Matching the wire gauge to the circuit’s current and run length prevents voltage drop and keeps lights bright.
Is 6-pin trailer wiring the same on every connector?
No. There is no single 6-pin standard that all manufacturers follow. At least two common connector formats exist — the small round plug and other 6-way layouts — and pin assignments differ between brands even within the same shape. Always reference the diagram that came with your specific plug rather than a generic guide.
Can I use a 6-pin plug on a trailer that only needs four wires?
Yes. Connect only the wires your trailer actually uses — typically white for ground, brown for tail lights, yellow for left turn, and green for right turn. Leave the blue brake and black auxiliary terminals empty or cap them. Make sure the tow vehicle’s brake controller is configured properly if electric brakes are installed.
References & Sources
- CURT Mfg. “Towing 101: Trailer Wiring.” Covers 6-pin color assignments and function descriptions for CURT products.
- Narva. “Trailer Plug Wiring Diagram.” Pinout for the 6-pin small round connector with terminal assignments.
- Croft Trailer. “Wiring Diagrams: 6 & 7 Way Connectors.” Color codes and function labels for 6-pin connectors.