7-Pin Trailer Plug, What Each Wire Does
Think of it as lights, brakes, power, and ground.
Standard 7-Pin RV Blade Layout
Pin Wire Color Function What it does?
- White Ground Common return for all circuits
- Blue Electric brakes Powers trailer brake magnets
- Green Right turn / stop Right brake light + turn signal
- Red 12V power Battery charging / accessories
- Yellow Left turn / stop Left brake light + turn signal
- Brown Tail / marker lights Running & license plate lights
- Purple Reverse / backup Reverse lights or aux function
7 PIN TRAILER WIRING DIAGRAM EXPLANATION
How It Works
– Ground (white) connects everything back to the tow vehicle
– Brown turns on all running lights when headlights are on
– Yellow & green flash or brighten when braking/turning
– Blue activates trailer brakes when you press the brake pedal
– Red supplies constant 12V power (charging a battery, interior lights, etc.)
– Purple comes on when the vehicle is in reverse (sometimes unused)
Important Tips:
– Wire colors can vary on trailers — always test if unsure
– Ground problems cause 90% of trailer lighting issues
– Electric brakes must use the blue wire (never tie into brake lights)
– Use a 7-pin tester or multimeter before towing
Get the PDF version of 7 PIN TRAILER WIRING DIAGRAM here
