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5 Wire vs 4 Wire System Demonstration

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Demonstration on 5 Wire vs 4 Wire Systems

To tell if your vehicle has a 4 or 5 wire system what you want to do is have a friend go ahead and step on the brakes. And note which lights come on. Now what you want to do then is go ahead and turn on the turn signal while holding the brake down and turn on the right turn signal. As you an see you have your brake lights on and you see the amber turn signal going on to let you know you have a 5 wire system. Now on this vehicle here we have a 4 wire system. The way to double check that is go ahead and turn on one of the turn signals like the right one here. Note which bulb is burning and which filament on the inside and turn that off. Then go ahead and hit your brakes. And you notice here, it is one in the same. So that means your turn signal and your brake lights are one in the same and you just use a regular 4 wire system you do not need a converter.



Have horse trailer 5 wire . Hooked to my 2006 dodge 3/4 ton. All lights work however when lights are on left turn signal does not work. Rear light appears to be brighter when light are on.

Patrick B.


Hard to say without the trailer in hand, but it sounds like a ground problem. If each individual function works on its own but things start acting funny when 2 or more are active, it almost always indicates that the ground connection is corroded, loose or otherwise has lost good metal to metal contact. The insufficient ground connection then no longer supports multiple functions.



All lights work on trailer, right

Patrick B.


The wiring kit in this video, part 119177KIT, would operate both turn signals, running lights and brake lights on a trailer. It would not operate reverse lights if the trailer were equipped with them.

E. B.


How do I wire a trailer with your 5 wire lighting kit?

Patrick B.


The video you were looking at was for a vehicle wiring harness. To wire a trailer you will need different parts. We have a really thorough Tech Article on trailer wiring that should be pretty helpful for you, linked below. If you are needing to install a trailer harness on a vehicle, let me know the year, make and model of the vehicle and we can find a wiring solution.

Keith S.


Have standard 6 wire plug on motorcycle with center pin constant power/axillary that is wired to a four wire trailer system. Have a Hopkins converter, p/n 48895 wired into female 6 pin plug to match wiring on the bike and the four wire system on the trailer. Have checked all connections and grounds repeatedly finding full line voltage at each tail/brake light/lic plate lamp. When attempting to use brake/turn application there is so little change in the appropriate filament as to be nearly invisible. All grounds, at each light assembly as well as from tongue to bike, are installed with star washers to improve contact. Have bypassed the ground with automotive jumper cable from trailer ground to negative post on battery to eliminate any possible miscues in the wiring system with no appreciable improvement. with bike running there is some improvement but not worthy of note. Attempted to install led tail/brake turn light assemblies and only one of the leds per assembly illuminated when power was applied. This puzzles me as the converter is supposed to be compatible with both leds and incandescent bulbs. Thanks for your help, Keith S.

Patrick B.


I am at a bit of a loss on this one. The one thing I can think of is your tail/brake/turn bulbs should have two filaments. One filament for the running light signal, and another brighter filament for turn/brake. Sometimes one will burn out, but not the other. Why you still have issues with LEDs is puzzling. There is one other thing you can check and that is the pin-out on the 6-way on the bike. There is a fairly universal pin-out for 7-ways, but there are a couple of accepted methods on the 6-way, one is more popular than the other. If you have not already, map out the 6-pin on the bike and make sure the adapter you built wires accordingly. Particularly if the grounds do not line up, then you may be getting a partial ground through the hitch ball which allows partial operation. I have added a link to a wiring article we have that has the more common of the two 6-way methods.

Brad S.


I have a 1994 Jeep Grand Cherokee which has a 5 wire system and my trailer has a flat 4 wire hook up . What coverter do I need

Patrick B.


There is a plug-in kit available for your 1994 Grand Cherokee, part 118349. You will have to run one separate wire up to the battery for power. You can use the FitGuide at the top of our home page to enter your year, make and model to find all the parts that will fit your vehicle. I have added links to the part as well as an installation video of the same part on a 1998 Grand Cherokee.

Info for this part was:

Employee Jeff D
Installed by:
Jeff D
Employee Kathleen M
Installed by:
Kathleen M
Employee Jacob T
Video Edited:
Jacob T
Employee Zach D
Video by:
Zach D
Employee Shane H
Test Fit:
Shane H

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