4-6-7 way Trailer and Towed light and brake hookups.  

4 Way Connector
4 pole plug
 

Flat 4 way wiring diagram
# Wire Color Function Location - Truck Location Trailer
1 White Ground uncovered pin covered pin
2 Brown Running Lights 1st covered pin 1st uncovered pin
3 Yellow Left turn/brake light 2nd covered pin 2nd uncovered pin
4 Green Right turn/brake light 3rd covered pin 3rd uncovered pin
4 pole round plug
*Note - Factory installed wiring harnesses frequently match the flat 4 colors.

6 Way  Connector
The wiring code for the 6-way connector is shown below. This is most commonly used on horse trailers, stock trailers, and utility trailers. Note that the wiring colors are the Pollack Company suggestions and not necessarily what you can expect to find. The terminal positions as pictured below are standard for this style connector.

When changing connectors match the positions from old to new or better yet test for function and be sure the connector is wired to the standard code.

Also notice that the center (A) terminal is not the brake terminal nor the ground terminal. The center terminal is listed as an auxiliary terminal and is used for either backup lights or a 12 volt (+) wire.

We recommend that this terminal be wired for 12 volt (+) for charging the breakaway switch battery. Breakaway switches are now pretty much required on most trailers with electric brakes and a charged battery is required for proper operation.

Wiring diagram
6 pole wiring diagram
plug body marked color function socket body
trailer end GD White ground car end
TM Brown Tail Lights
LT Yellow Left Turn
S Red Stop or
electric brake
RT Green Right Turn
A Blue Auxiliary
Trailer End NOTE: center terminal is A Car End

ASME Wiring Color Code
Terminal Marking Wire Color Function
GD White Ground
TM Brown Running Lights
LT Yellow Left turn/brake light
ST Blue Brake Control
RT Green Right turn/brake light
A (Aux) Black Power
 

RV Wiring Color Code
Terminal Marking Wire Color Function
GD White Ground
TM Green Running Lights
LT Red Left turn/brake light
ST Blue Brake Control
RT Brown Right turn/brake light
A (Aux) Black Power

7 Way RV Connector
Pictured below is the Pollock 7 way connector, which is the connector style in most common use on RV trailers and is becoming increasingly popular on horse and utility trailers. This connector is also manufactured by the Theodore Bargman Company and there are also some generics around. They are supposed to be interchangeable and the wiring color code is maintained among the various brands.

As you can see in the illustration below the back side of the connector body is labeled at each terminal. The labels are listed below with the function assigned to that pin.

On the tow vehicle side with the exception of 96-98 Ford and Dodge pickups and SUV's with factory installed trailer wiring, wire color alone should not be relied on, always test and match the function to the appropriate terminal.

On the trailer side RV's for the most part are wired to match the connector colors. Any plug that has been changed or extended, along with horse and utility trailers should be tested when replacing for any reason to be sure the function matches the terminal.

It should be noted below that the center terminal is labeled as an auxiliary circuit, most commonly used for backup lights not a ground terminal as many try to make it.

Also after the connector diagrams find more information on wire colors used by GM, Ford, and Dodge.

Wiring Code 7 way Car End
# Color Gage Circuit Function connector interior
1 white 10 common ground [7 way connector]
2 blue 12 electric brake
3 green 14 tail/running lights
4 black 10 battery charge (+)
5 red 14 left turn/stop
6 brown 14 right turn/stop
7 yellow 14 auxiliary/back up
NOTE: #7 is the center terminal and currently is most commonly used for backup lights.

Wiring Code 7 way Trailer End
# Color Gage Circuit Function connector interior
1 white 10 common ground [7 way connector]
2 blue 12 electric brake
3 green 14 tail/running lights
4 black 10 battery charge (+)
5 red 14 left turn/stop
6 brown 14 right turn/stop
7 yellow 14 auxiliary/back up
NOTE: #7 is the center terminal and currently is most commonly used for backup lights.
This chart should be used as a general guide only, you should always test before connecting your wiring.

This chart also may not be accurate for vehicles with factory installed trailer harnesses. In past 2-3 years manufacturers have begun to match the wire colors to the code for the common 7 way RV connector. More on that after the chart.

Caution if your vehicle has a diagnostic indicator that tells you when a lamp is burned out or not functioning, you may need special wiring adapters and testers. Not using these adapters may cause damage to the vehicle wiring or computer.
function GM Ford Chrysler
left turn & brake lights yellow lt green w/orange stripe dk green
right turn & brake lights dk green orange w/blue stripe brown
tail lights brown brown black or black w/yellow stripe
back up lights lt green black w/pink stripe violet
ground - see note 1 black black or grey black
In addition to the above some cars and trucks have a separate light for the brake light, most commonly identified by amber turn lenses in the rear. Chrysler and Jeep may have the separate light and use red lenses. If you have this type of wiring a converter is required.
brake light lt blue or pink red w/green stripe white
Note 1: We recommend attaching the trailer harness ground directly to the frame or a solidly attached sheet metal part, using a screw or bolt. The single most common cause of trailer lighting problems is a poor ground on the tow vehicle or trailer.
Notes about GM OEM wiring harness. Most GM vehicles except '99 & 2000 Silverados match the following.

GM trailer wiring code
white ground
yellow left/brake
green right/brake
brown tail
light green backup
blue trailer brakes
red * 12 volt +
* Pickups only: since approximately 1996 the 12 volt + wire is orange. The orange and blue wires are in a separate bundle taped to the wire harness that runs down the frame on the drivers side. A white wire may also be found in that bundle, it is a brake light wire which is not normally used for trailer wiring.

Dodge tow vehicles with the Factory Tow Package Brake Connector Dodge vehicles with this package are equipped with a 15 amp fused power line which is insufficient for 3 & 4 axle (6 or 8 brake) applications. For 3 & 4 axle (6 or 8 brake) applications a separate power wire should be installed directly from the battery positive to the brake control and should include an inline 30 amp auto reset circuit breaker.

Ford tow vehicles with the Factory Tow Package Brake Connector Ford vehicles with this package are equipped with a 20 amp fused power line which is insufficient for 3 & 4 axle (6 or 8 brake) applications. For 3 & 4 axle (6 or 8 brake) applications a separate power wire should be installed directly from the battery positive to the brake control and should include an inline 30 amp auto reset circuit breaker.