View Full Version : Replacing a Flat 4

01-28-2006, 01:29 AM
My flat 4 on my trailer is broken on my trailer. All of the male prongs are bent and can not be use so I have to replace them. I bought a replacement flat 4 and plan to change it out soon.

The flat four on the trailer has 5 wires conneceted to the prong, but the new one only has 4 wires. What do I do with the left over wire. Should I connect it to another wire or just leave it hanging loose.

Some one help me please.


Jason Rose
01-28-2006, 01:56 AM
A standard Flat 4 plug has "standardized" coloring for the wires. Assuming that your vehicle and the trailer were originally wired using the properly colored wires...

Ground - White

Taillights (clearance)- Brown

Right Turn - Green

Left Turn - Yellow

There are other colors for wires, used in 5 flat and round, 6 round, and 7 round pin and RV type plugs.
This is the complete list:

S* Brakes - Blue
GD Ground - White
TM Taillights - Brown
RT Right Turn - Green
A* Accessory (or back-up lts.) - Red
LT Left Turn - Yellow
Direct battery feed - Black

These are the industry standard color scheme. Of course not all plug manufacturers go by this, but most do.

Depending on the color, or where that 'extra fifth wire' leads to will tell you what it is. A cheapo continuity tester (looks like an ice pick with a little cord and a light bulb inside) will be your best friend for tracing wires on the plug ends on your vehicle.