Trailer Wiring Diagrams
Posted by BobWms on April 19th, 2006
Wire Installation Tips
By law, trailer lighting must be connected into the tow vehicle’s wiring system to provide trailer running lights, turn signals and brake lights. This is accomplished by tapping into the tow vehicle’s harness power to the trailer wiring system. Connectors are used between the two to allow disengagement when not towing.
Various styles of connectors are available with four to seven pins to allow transfer of power for the lighting as well as auxiliary functions such as electric trailer brake control, backup lights, etc. Choose a connector that has the required number of pins for the functions required. The male end (plug) is mounted on the trailer side and the female end (socket) on the vehicle side.
6 Way Connectors
Round 1 1/4″ diameter metal conductors are available that
allow 1 or 2 additional functions such as back up lights and electric brakes.
7 Way Connectors
Additional pins for auxiliary power, trailer battery charging, etc. are
available using larger 2″ diameter, round connectors.
7 Way Trailer Plug, Flat Pins
7 Way Trailer Socket, Flat Pins
6 Way Trailer Plug, Round Pins. Sometimes called “Ranch Standard”
6 Way Trailer Socket, Round Pins
August 13th, 2006 at 21:32:42
I found this information very useful and I give an atta-boy x10 to the person making this entry.
September 13th, 2006 at 08:49:23
do you have a diagram for the AG plug with 7 round pins ?
September 13th, 2006 at 15:17:40
I’m researching this. Frankly, I don’t think there is such a thing as 7 pin round small plug. The only seven connector socket I’ve seen is the larger (2″ diameter) flat pin connector normally used in rv’s, semi and over the road trailers that have anti-skid brakes.
I operate a electrically operated hydraulic dump trailer that uses a #6 gauge welding lead to feed 12 volt, 150 amp to the trailer’s motor. I had to use a separate lead for that, due to it’s size.
September 13th, 2006 at 15:31:26
Every time I say “Ain’t no such thing” I get educated. Here’s this:
http://www2.northerntool.com/product/200303933_200303933.htm
I looks like it will adapt the rv socket to a BIG 7 way pin plug. If there’s adapter for it, there has got to be such a plug.
Good Luck!!
October 29th, 2006 at 12:14:57
MY TOWMASTER T-40 TRAILER WITH ELECTRIC BRAKES WIRING GIVES NO WAY FOR THE BRAKE ASSIST BATTERY TO BE RECHARGED DURING SERVICE . I WOULD LIKE TO CHARGE THE WET CELL DURING NORNAL USE OF THE TRAILER. HOW??
( AT PRESENT THE ONLY TIME THE BATTERY DOES ANYTHING IS WHEN THE BREAKAWAY SWITCH IS CLOSED AND THAT FEEDS 12 VOLTS TO THE BRAKE MAGNETS.)
THERE IS NO WAY AT ANY TIME THE BATTERY GETS A REFRESHER CHARGE UNLESS I HOOK UP A CHARGER TO IT.
November 6th, 2006 at 09:22:15
A lot of people will simply tap into the TM circuit with a small jumper wire. Do this on the trailer plug side and don’t forget a small inline fuse. 2 or 3 amps should be plenty. Normally that battery won’t need much more than a trickle charge and it will then receive that charge anytime your trailer lights are on.
Be sure that your breakaway battery is fully charged at first.
PS: Sorry for the delay in answering…don’t know why I didn’t get email notification of this comment. One more website thing to look at….
November 18th, 2008 at 21:32:40
Ok I keep finding these diagrams different then what I have. What I have is a Tekonsha trailer brake with a 7 pin connector. My wire diagram from the manufacture is for my motorhome female reciever starting at
1 o’clock black 10 gauge battery charger
3 o’clock brown 14 gauge right stop/ turn
5 o’clock blue 12 gauge trailer brakes
7 o’clock white 10 gauge common ground
9 o’clock red 14 gauge left stop/ turn
11 o’clock green 14 gauge tail license
center yellow 14 gauge
So I tested my system and it all works. It was installed by a shop
July 29th, 2010 at 10:31:08
I have a 97 jeep grand cherokee limited and none of the wire colours that are outlined here or anywhere else match the wire colours of my 7 way factory installed plug, which was wired totally incorrectly from what i can see, whats left is Corroded green dust. I do not have a white ground wire, I do have a light blue 10 gauge wire (ground i think) and a black 10 gauge wire which I’m assuming is the power wire.
then i have a light brown wire (Yellow i think left siganl), a green wire with a brown stripe (?), a lime green wire (right signal), a blue wire with a red stripe (?) and a red wire.
I have managed to get brake lights and signals but no running lights so far.
any help would be appreciated because i am leaving on vacation tomorrow and I have tonight to complete this nightmare.
July 29th, 2010 at 11:38:37
Anon,
The only thing I can offer is to put a tester on that lt. blue wire and see if there is current when the running lights are on. When a vehicle socket is not installed correctly, it’s sometimes difficult (if not impossible) to correct.
July 29th, 2010 at 13:22:15
thanks for your response bob, I went and bought a brand new 7 wire connector and a new 4 wire trailer plug. I will use the meter as you suggested and isolate what does what, then wire the jeep connector as outlined in the diagrams i found.
Once i get the vehicle plug installed i will then connect the four plug on the trailer. The original trailer plug had 5 wires in it with 4 ports……… the trailer plug people where dumbfounded when i showed them the 5 wire 4 plug and shook their heads in disbelief because they had never seen one like that.
ground pin, then a green and yellow wire on the same pin then a yellow wire and last a green wire.
very perplexing to say the least……
July 29th, 2010 at 14:35:31
I’ve heard of regional differences, but I’ve certainly never heard of that! Thanks!!