Trailer lights issue please please help driving me nuts!

[PISTONESAL]

Please help. I am at a stump and cant figure it out. My trailer left turn signal is dim, right works, brake works but the left is dim. All this works only if running lights are off, if they are on, nothing works at all. Seems a bad ground but I have checked it over and over. I have my 4runner that I replaced the convertor on thinking it was the issue. Tail,brake, left and right turn all works on the 4 wire connector on the truck, testing with a light tester. To help troubleshoot, I hooked my brother in laws jeep to trailer and everything was working perfect but with my truck i get the above issues but the tests at the wire connector are good. Please somebody help. I am at a lost. All connections are good. If the tests on truck are good and with the jeep hooked up to trailor is good, what can it be?. I need to find a person with a working trailor to hook my truck up to it to confirm but the light tests on connector pas so it seems like everything works on the truck. Please help!!! thanks

 

[Bondo]

Seems a bad ground but I have checked it over and over.

Ayuh,..... I agree,.....

Do ya have a set of jumper cables,..??
If so,... Hook 'em up from a clean clear shiny metal point on the trailer frame, 'n to a clean clear shiny metal point on the tow vehicle,...
My guess is,... the lights will then work Perfectly,......

Ya can't count on the electrical contact of the ball, 'n coupler for a good solid ground path,....

 

[PISTONESAL]

Great idea and you know what, I tried that already. Now you can imagine how frustrated I am.. The ground from the plug is suppose to be the good ground..

 

[alldodge]

Disconnect the trailer from the truck and either get another 12V bat, jump start bat, or put the truck facing the tongue of the trailer. Use jumper cable to connect to frame and Neg bat. Attach another wire (not other jumper cable) to Pos terminal on bat.

Connect wire one at a time to Brown, Green and Yellow wires. If all lights correctly, connect to Brown and to Green and look at lights, Right side should be brighter then Left. Remove Green connect and connect to Yellow, Left side should be brighter then Right.

If all checks out the problem is not the trailer, its in the truck

 

[bobofthenorth]

Its the ground on your truck. Put a good ground connection to the connector on the truck and your problem will go away. You've got a high resistance ground on the truck connector. If you're got a VOM and know how to use it then test the ground pin on the truck connector against a clean ground. Otherwise just replace the ground connection.

 

[PISTONESAL]

All dodge, don't quite understand what you stated.? It's a little confusing. Can u make it clearer please? I did ohm out the ground of truck to connector and has good continuity.

 

[Baylinerchuck]

Sounds like you have the right voltage on the wrong pins. Like ground is being fed through the running light circuit from your truck to the trailer. You need to confirm with your tester that you have 12v where you need to have it.
Leave trailer disconnected. Just use the trailer plug and wires as a reference. You already confirmed the trailer is fine. White is your ground or negative, black lead here. Only +12v on brown with running lights on. Only +12v pulsing on green with right turn on. Only +12v pulsing on yellow with left turn on. +12v on both green and yellow when brakes pressed.

 

[alldodge]

All dodge, don't quite understand what you stated.? It's a little confusing. Can u make it clearer please? I did ohm out the ground of truck to connector and has good continuity.

Want to test the trailer lights without using the truck, just a 12V source. I'm thinking there is a mis wire or one of the lights on the trailer is causing the issue on the trailer

 

[PISTONESAL]

Thanks but all the lights were working and out of the blue this happens. Bayliner chuck, the trailer light worked perfect with my brother in laws jeep as I had stated..

 

[bobofthenorth]

..I did ohm out the ground of truck to connector and has good continuity.

You'll often see that on trailer connections - you appear to have continuity but it can't handle any load. Fix the ground - that's where the problem is.

 

[alldodge]

the trailer light worked perfect with my brother in laws jeep

Then its not the trailer, its your truck. Something may have happened to the adapter or wiring harness. The Toyota needs an adapter in most cases. Don't know what year your 4runner is, but just search for it.

 

[lmuss53]

Bobofthenorth has hit it here. It is almost certainly the truck ground. If you want to check it run a wire from a clean place on the trailer frame to a similar clean place on the truck frame and watch the lights work correctly. The existing ground may have continuity, but it is frayed or corroded somewhere to the point that it can not carry the current that it needs to. The corrosion or frayed wire could be anywhere in the truck harness, or the connectors.

 

[PISTONESAL]

Ok I hooked jeep again and lights act just like my truck so issue is on trailer? What do I do or check now? Please help thanks...

 

[Grub54891]

Start over. Replace the entire harness, and lights. You can get a complete kit, preferably led set up, maby a bit more pricy but worth it. I personally run the ground to each light, assuring good contact through the whole rig. Do not use the scotch lock connectors. Use good shrink wrap type crimp terminals all the way through the entire setup.
Good luck!

 

[alldodge]

Post 4

 

[lmuss53]

It is still a ground. I say that because the lights come on dimly. To test that run a wire from a clean spot (shiny bare metal) on the trailer frame to a clean spot on the vehicle frame. Ground wires, in fact the entire harness, very often corrode, get smashed, pinched, stretched, cut, flattened, pulled, whatever and get a bad or intermittent connection. An open, broken ground wire will often cause the trailer to ground back thru the hitch and ball, resulting in an intermittent or insufficient connection like you have. The test form bare metal to bare metal will confirm this issue.

If the entire trailer harness is in iffy condition go ahead and replace it like Grub suggested.

I think you will find your problem in the trailer connector ground (usually white) wire somewhere from where it touches the truck plug to where it touches the frame. I have seen the pin on the connector be broken off and that not noticed. I have seen that pin be corroded inside the connector to the point where it can't move enough current to do it's job. I have wiggled the pin a bit and had it pull out in my hand like a loose tooth.

More often the culprit is where the ground wire attaches to the trailer frame. That entire connection has to be very suspect in this situation. It can look perfectly fine and even have continuity thru it, and not be sufficient to carry the required load, resulting in exactly the issue you are having, When you clean the spot on your trailer frame do it close to this connection. If the test from trailer to vehicle works, cut the wire going to this connection close to the connection, strip it off and touch it to your clean spot. If everything works redo the whole ground wire to trailer connection from attaching hardware to connectors, making sure you have a clean spot on the frame to start. If it doesn't work, but the test wire did, replace the 4 pin harness on the trailer.

 

[PISTONESAL]

Well the light kit is not even 6 months old and is the LED type which was over $60. I have cleaned a good spot on trailer with a wire brush for the white ground. I did use the heat shrink type connectors and also put the liquid nail over them for extra protection. I will try the jumper cable from trailer to truck frame and go from there. It's been driving me nuts.. What other way can I get a clean bare metal on trailer?

 

[GA_Boater]

The left light is dim and the only ground on the trailer is the white wire from the trailer connector to the frame.

Do this - Run a wire from the white frame connection to one of the left light mounting studs (the ground for the lights) and see if it works.

Do you have a tilt trailer?

 

[lmuss53]

The wire brush should get you clean grounds. I'm still leaning to an overall ground from trailer to truck, because everything gets dim or goes out when you turn the parking lights on. That happens because you add all the running lights to the load and then the bad ground can't carry enough to let anything work right,

I think I see where you're going with the tilt trailer GA_Boater, it's possible he is losing the ground thru the hinge on the trailer.

Pistonesal, you never say if you ran a wire from clean trailer to clean truck to test the ground. To me that is the very first step to finding your problem. If that makes everything work right, you know you have a ground issue, and the problem is somewhere from the truck frame to the trailer frame in the wiring harness ground wire. If it doesn't help then you can safely assume the problem is in the wiring in the trailer harness, or, like I think GA Boater is suggesting, the hinge on the tilt trailer is not letting the current through. I think you'll find the ground wire is bad somewhere.

 

[GA_Boater]

^^^^ Yes. A tilt trailer with the ground attached to the tongue is a poor ground path and causes flickering and dim lights, especially while towing as the hinge bolt/tongue moves around. Same thing happens using the ball for the ground path.