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.
Also if you do not have that ground screw in the body it is easy enough just to make your own. We just use a self tapping screw, like we did right here. To make a fresh ground, we just used this screw going to the sheet metal here. Then we go ahead and test it. Before you do any connection you want to make sure your tester is working. You do that by testing a circuit you know is live all the time. That would be basically your running lights. So in this instance we are going to go ahead and ground it to the ground screw here. Then we will go ahead and turn on the running lights. When they are on, what you can do is take your light tester and put it on the wire and pierce it like so. You can do that with every wire that is hot. The best way to do that is right behind the tail light so you know when your tail light is on that at least one of the wires has to be hot. If you go through all of these wires and one is not hot, chances are your ground is not good.
Another good ground you can use is the tail pipe because the block itself is grounded to the battery. You can clean a section of your tail pipe off, use this your clip and do that. You can do that if it is easily accessible. The older the vehicle, the more cleaning you have to do, it is up to the individual. But usually you can find a good ground and you can also make a ground on a couple pieces of steel that overlap. We can see this little wield line right here. This is actually a really good spot to put a ground in. Basically make sure it is not going to the outside or will mess up the taillight or anything. But, anywhere you see two pieces of metal overlapping, chances are you have more steel to go into, and the better chance that it will be grounded steel. With more steel the less chance you are going to strip out the screw as you tighten it down.
Questions and Comments about this Video
Just put a new 4 wire trailer light kit on my small boat trailer. Plugged kit into wire harness on truck, turned light switch on and all 4 lights came on as advertised, then turned on turn signal and all four lights were blinking, no matter if it was the right or left turn signal. Is this a bad ground wire?Thanks
comment by: Jerry N - 11/7/2012
Bad grounds could lead to bleed over from circuit to the other. Check all your grounds and make sure they are on good, clean metal with no rust or oxidation. Check the connectors themselves, particularly on the vehicle since your trailer connector is new, and make sure it is clean. Corrosion can build up inside and cause connections to bleed over to the next. Finally double check all your wiring. The standard color code for trailer 4-Poles is as follows: White - ground, Yellow - left turn, Green - right turn, and Brown - tail/running lights. I have added a link to a our wiring FAQ page that shows the basic wiring schemes for trailers.
Patrick B - 11/12/2012I cant figure out why my brake lights arnt coming on. I think its the connection on the vehicle side between the car and the plug. The running lights and turn signals all work but the brake lights on the plug and at the trailer tail lights dont come on. I just ran a ground all the way from the battery to the white wire for the plug and they still dont come on. This is a four wire flat connection. Whats going on?Thanks for your help,Robert
comment by: Robert - 12/6/2012
Check the fuse/power distribution blocks first. Both in the cab and in the engine bay. It could be a fuse burned out that sends brake light signals to the 4-pole. If it is an aftermarket trailer wiring harness and has a converter box, use a circuit tester like 3808 to check before and after the box. If you have brake signal going in, typically the red wire on a converter box, but the signal is not coming out on the green and yellow wires, then the box may be bad.
Patrick B - 12/10/2012This 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 7-Pole Connector
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
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
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
