Today on This Old Trailer we are going to diagnose some wiring problems. The problem with this trailer is that when you plug the trailer into the vehicle none of the lights work. It could be a variety of problems but the first thing we are going to do is start from the front and work our way back. Just to make sure there is nothing wrong with the towing vehicle use an independent power source to power up the trailer just to make sure. Then we will turn on the lights and check in the back. We have got our power supply on and it looks like there is nothing working in the back and also it looks like the running lights were not working either. Lets go back up to the front and check the connector. 00:33
First off we will inspect the connector itself. It looks like it has been around awhile and you can tell the leads on here, kind of a dark color, so that tells you that it is oxidized and will not allow current to pass through very easy. An easy trick is to maybe scratch it and see if it comes back to life. We are going to use a small screwdriver and kind of go in there and clean out the tabs and see if we can get anything working after this. We will reconnect to the power supply and check again. With that simple little test we have got the running lights working so lets check the rest of the trailer. It looks like we have got one tail light in the back that is not working so we have got our running lights. Lets check the turn signals just to make sure. It looks like our left turn came to life so we are good there. Lets try the right turn. We do not have anything there either so it could be A: the connector, or B: something is wrong with the light. Since the connector is pretty dirty anyway lets replace that connector and start fresh from there. 01:37
To take apart the connector, we have the screw in the back to remove and a little set screw up towards the front to the remove. Then we will cut away some electrical tape and try to slide the cable in and out. Push it out the front. We have got a good look inside of here. All of the connections are pretty tight but everything is starting to rust up and start to corrode just a little bit so it is probably a good idea to replace the connector anyway. This is our new 7-pole connector and we are going to be using part number PK12706. We will assemble the connector like we did before and we are going to take our wires and push them back through to the front and work it in. Lets get the wires in order here. You can twist these and put them into the clamps in the connector like they were originally or you can put on some small ring terminals too which I think that is what we will do. Now we will connect our wires to our 7-pole. If you noticed on the 7-pole itself that all of the little tabs or lugs are all labeled different colors. It is not going to be a color for color match because the colors on here are going to be different from the colors on the trailer wire harness. 03:19
We will start off by what color we are going to use and we will show you where to go on the 7-pole. We will start off with the only one that actually matches and that is going to be white. So we are going to put white to white on the 7-pole. When you install it with the ring terminals, have them facing down like this so you have it going this way all the way around they will fit in the connector as well. We will move on to our next color. This is going to be the brown wire and the brown wire on the trailer is going to be the running light circuit and the running lights on the 7-pole connector is going to be green. We will work with green on the trailer wire and that is going to be right turn so the right turn is going to be brown on the 7-pole connector. Our last color yellow that is left turn on the trailer and it is going to be red on the 7-pole. Lets push everything back together and install a little set screw. Move to the back side here and put the clamp and set screw in and it is a nice tight connection. Place some electrical tape here. Lets plug this back into our power supply and see if we get any better results. Lets apply power to see what we get. First off we will try running lights and it looks like both of them are working. Now try the brake lights, that is good. Then we will try our right turn signal and that looks good. Try the left turn signal. Okay it looks like everything works. There you have it for replacing a 7-pole connector on This Old Trailer using part number PK12706.
Questions and Comments about this Video
I would sure like some help my old trailer has running lights in the back and brake lights and turn signals but on both side I did some work and cut the wires that used to be running lights there are two wires on the drivers side in the middle and there are 3 wires on the passenger side in the middle both near the fenders...the problem is when I plug it in the plugs gets really hot in just a matter of minutes it will burn you so I un plug it can you tell me about the loose wires in the middle on both sides
comment by: les k - 9/27/2012
With the plug getting hot, it sounds like you have a short to ground. Without seeing the wires, it's impossible to determine what each line is. Typically, the color code is as follows: Green - right turn/brake, yellow - left turn/brake, brown - running lights. Not all trailers are wired according to this code, so a circuit tester like part # 3808 is used to determine which wire is carrying which function. Someone would run the lights from the vehicle and you would use the tester to find out which wires do what. There could also be a wire that carries a reverse light signal and another that could have been used for carrying a brake feed for electric brakes depending on the size and application of the trailer. A circuit tester is really the best way to determine what wires should do what.
Patrick B - 10/1/2012What wiring harness would be used to rewire a trailer like the one in the video?Thanks.
comment by: Randy S - 10/19/2012
The connectors are going to be determined by the lights you are using and the connector on the tow vehicle. For the most part, you would either use a bonded 4-wire, bonded 5-wire or jacketed 7-wire set-up. The trailer in the video uses a 7-pole so you would want a jacketed 7-wire setup. You could use part H20046 that already has a molded connector on the end. You could also use something like part DW04914-1 that is sold by the foot so you can get the right length for the trailer. I'll link to both below.
Patrick B - 10/19/2012What color wire goes in the middle and is that wire hot or simply a ground??My Surburban has a light green wire going there in the middle..My electrical line making a u turn ripped all the wires about 2 feet from the pug to Suburban and the plug is missing so i dont know how to run wires..I have the POLLAK 12-705 on my Suburban with a BLUE then DK.GREEN then a thick ORANGISH RED, then a BROWN, then a yellow, then a thick WHITE......The middle wire is a light green.I have the electrical brakes..and upper marker lights on an enclosed trl...The trl wires are red,yellow blue,green,brown and a thick WHITE, and a thick BLACK wire...CONFUSED...as of now i have a PEP Boys generic connector i bought and it says at 1oclock,4BLACK..at 3oclock 6BROWN at 5oclock it says 2 BLUE,and at 7oclock,1WHITE, at 9 oclock it says 5red and 11 oclock it says 3green and the middle screw says nothing..So, that leaves me with a yellow wire left... so i would think that would go in the middle....7 total wires...CAN U HELP. thanks...I need to use the trl. at 10am EST. TODAY OCT27TH...If u get this memo and can help asap that would be great..thanks again
comment by: GREG - 10/27/2012
Wiring colors on vehicles are not standardized. Most trailers follow the same protocol, but yours varies a bit. The center pin on a 7-Way is for reverse lights, unless someone has wired it differently. From the factory, that center would be reverse. I have an FAQ page that I have linked that goes over a lot of wiring information. The best recommendation I have is to grab a circuit tester and verify the way your truck 7-Way is wired before you wire up your trailer connector.
Patrick B - 11/12/2012This Old Trailer: Repairing a Trailer Light Wiring Problem
Today on This Old Trailer, we are going to fix some lighting problems. Now what is happening on this trailer is that one side of the taillights is not working at all and the passenger side sometimes works and sometimes does not. So the first thing we need to do is go ahead and check to make sure we have power going all of the way back. That means we will start from the front and check our way on to the back. The first thing we need to do is go ahead and apply power. We are going to start checking our power from the plug on back. What we are going to do is actually take out the screw that holds the connector together. We are going to push it inside then we are going to pull it apart. Then we can see the contacts on the inside. We are going to turn on the running lights and we are going to hit the brakes for the taillights themselves. So, we should have three wires hot. We will go ahead and check that. It looks like we have power for a second here and it went away. We will try the other two. It looks like the same thing. So it looks like we are dealing with some multiple shorts. So we know it is something definitely on the trailer at this point. So we will go ahead and go back to the taillight and start doing a visual inspection. 0:57
This Old Trailer: Replacing a 6-Pole Connector
Today on This Old Gooseneck Trailer we are going to install part number PK11604 from Pollak. This is their 6-pole connector and we are going to replace the one that is originally on this trailer right now. Now, what has happened to this one is it has been basically pulled apart a few times and basically the insides are getting worn out and some of the screws a striped out. So, we are just going to go through it and replace it. The first thing we want to do is go ahead and take out this screw and this screw here. This little screw right here, this is kind of a clamp that holds the cable in place. Then this little set screw holds the inside in place and in alignment. OK, let us push that on out. Now, when you go ahead and take these wires apart, note which wires go to what. On the inside of the connector they are all labeled left turn, right turn, TM for trailer marker lights, S is for stop which will be for brakes typically and you have the A in the middle for auxiliary for whatever you want to use and then you have GD for ground. 0:55
Testing for a Correct Ground Connection Demonstration
Today we are going to show you a little bit on wiring. Basically, a wiring 101 or what to look for when you hardwire into a vehicle. Hardwire means actually getting to the wires and splicing into them and making a connection. The first thing you want to do when you hardwire a vehicle is you want to make sure you are grounded and get a test. Make sure your tester is working fine. On some cars you will see this on one of the wires. Being the same color like these black wires. You will see a lot of them ran to a screw inside the body here. Chances are that is going to be your ground. You can actually use that ground for your light tester. What we mean by a light tester is a device like this right here. Basically, this connects to the ground and what this device does is this hooks around the wire you want to test and you push it together and it precises the wire and touches the copper wire inside, creates a circuit and lights up when you have power in that wire.
Circuit Testing for Vehicle Wiring
Today we are going to show you a little bit of wiring. Basically, like a wiring 101 and what to look for when you are going to hardwire into a vehicle. And what hardwire means is actually getting to the wires and splicing into them making a connection. We will go ahead and do our test and ground it. Instead of piercing the wires, if you have a junction that is easy to get to go ahead and pull it apart. And instead of piercing the wire, go ahead and test on the inside here. Just check each individual contact here until you hit something. Then make sure you actually have your running lights on and then go ahead and turn them back off. It also proves to us that our ground is good and it is working with our electrical system here.
5 Wire vs 4 Wire System Demonstration
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.
Trailer Wiring Diagrams
