still trying to figure out my wiring issue....

[ngt]

Ok, so I was having trouble with the lights on my car and trailer. It was a ground wire in the trunk. I fixed it and now the car is 100% fine, but the trailer is still having an issue.

The problem. When looking at the back of the trailer, the left side works perfectly all of the time, but when my headlights are on, the right side doesn't go on. Everything else works perfectly all of the time now, except that right side. I really want to be able to leave home before the sun comes up to get to a fishing spot.

Any ideas? What would cause one side not to work?

thanks

 

[Al Kungel]

Re: still trying to figure out my wiring issue....

Let me see if I understand this correctly.
1) With no lights turned on (parking or headlights) the signal & brake lights work on the trailer and vehicle?
2) When you turn on either the parking or headlights, only the lights (running, signal and brake lights) on the left side of the vehicle and trailer work, but the right side of vehicle and trailer do not work?
Can you clarify.

What happens when you turn on the four-way flashers with the running lights on and off? If the four-way flashers are not working properly then you probably have a ground issue.

Nine times out of ten on trailer lights it is a ground isssue.

 

[j_martin]

Re: still trying to figure out my wiring issue....

Let me see if I understand this correctly.
1) With no lights turned on (parking or headlights) the signal & brake lights work on the trailer and vehicle?
2) When you turn on either the parking or headlights, only the lights (running, signal and brake lights) on the left side of the vehicle and trailer work, but the right side of vehicle and trailer do not work?
Can you clarify.

What happens when you turn on the four-way flashers with the running lights on and off? If the four-way flashers are not working properly then you probably have a ground issue.

Nine times out of ten on trailer lights it is a ground isssue.

The ground return is bad on the trailer right side. When the running lights are off, the turn signal current returns through all the running lights, both trailer and car to ground. It seems normal. When you turn on the running lights, the return path on that right side bulb is to 12 V, so no current flows, and the light doesn't light.

 

[ngt]

Re: still trying to figure out my wiring issue....

The ground return is bad on the trailer right side. When the running lights are off, the turn signal current returns through all the running lights, both trailer and car to ground. It seems normal. When you turn on the running lights, the return path on that right side bulb is to 12 V, so no current flows, and the light doesn't light.

How would I fix this?


as for my issue...sorry if I was unclear. Everything always works fine on the car now. When the headlights are off, the trailer lights all work perfectly. When the headlights are on, the right tail light on the trailer does not work, but everything else is fine. Hope that made sense.

If that still means I have a bad ground return, again, how would I go about fixing that?

thank you for the help!! This would make my fishing times start an hour earlier and end an hour later

 

[nlain]

Re: still trying to figure out my wiring issue....

I had a similar problem on my trailer, right taillight would not work, I had to replace the light assembly to fix mine. There was even a ground wire attached to the mounting stud for that light, I took that apart and cleaned and reconnected before I changed out the light. You say when the headlights are on the right trailer taillight does not work, most people just turn on the lights which as a rule turns on the headlights, I'm thinking that if you turn on just the parking lights the same will be true, if it is replace the light.

 

[ngt]

Re: still trying to figure out my wiring issue....

I had a similar problem on my trailer, right taillight would not work, I had to replace the light assembly to fix mine. There was even a ground wire attached to the mounting stud for that light, I took that apart and cleaned and reconnected before I changed out the light. You say when the headlights are on the right trailer taillight does not work, most people just turn on the lights which as a rule turns on the headlights, I'm thinking that if you turn on just the parking lights the same will be true, if it is replace the light.

even if the lights on the right and left both work fine without the headlights on? and they are brand new lights? I don't understand how that can be a problem with the actual light. Again, I am new to this so it's most likely just me not knowing...but it doesn't sound right.

The right side running light is not on either when the headlights are on..

...so no right side of the trailer at all with the head lights on.

I kind of understand that ground return thing, as it makes more sense to me...although not 100%, as I don't know much about this stuff...but I would like to know how to get past that issue.


thanks for the help guys! Hopefully I can get this fixed.

Any other ideas?

 

[nlain]

Re: still trying to figure out my wiring issue....

In my case the old light had lost ground within the light itself, I would think new lights would not have that problem. Nothing on the right side, there should be a brown wire that splits and runs down each side of the trailer, that wire supplies power to the running and tail lights, get a test light and check for power in that wire, you could have power to the left but not to the right. You know you have power thru the plug since the left side works, test the right side, the wire may be broken somewhere between the plug and the lights. I believe the brown wire comes out of the plug as two wires, it is even possible it does not have connection in the plug. Anyway check for power to the lights, either no right side power or no right side ground. Some trailers are wired with a ground to both sides, some even with the ground run to each light, since frame ground does not always work.

 

[ngt]

Re: still trying to figure out my wiring issue....

Cool, I'll check the power on that brown line. One thing though...why would it work on the right when the headlights on the car are off, if it's not getting power? That's what I don't understand.


thanks again!!!

-E

 

[nlain]

Re: still trying to figure out my wiring issue....

Cool, I'll check the power on that brown line. One thing though...why would it work on the right when the headlights on the car are off, if it's not getting power? That's what I don't understand.


thanks again!!!

-E

If I read this right you just posted that if you turn on just park/taillights on your car that both taillights on the trailer burn, but you turn on the headlights on the car then the right side of the trailer goes out. Now you are getting something in the strange category. Somehow it has to be in the headlight circuit, are both headlights the evenly bright, I am thinking ground circuit again for the headlights that somehow is running to the right side of the trailer and killing those lights, maybe through the right turn signal. I wish I could put my hands on this one it is strange. I have seen many strange things in my 50 years of life, I did automotive electrical work for years but this one is somewhat a puzzle. You may even have a combination of things here that are masking each other and making is really difficult to find. You are at a point now that you need to forget everything you have fixed, replaced, repaired or checked, go back to square one and start at this like you have never touched it before. There is something that you do not see and it is difficult to find but probably staring you in the face. I have been there done that. Start testing, turn on the park/taillights, test the wires for power including the ground wire, test light should not light on the ground wire, if it does ground is bad, turn on headlights, retest, in this series of tests check both the car and the trailer, hopefully you will find it.

 

[ngt]

Re: still trying to figure out my wiring issue....

cool. Yeah, thats what is happening. Everything on the trailer is fine when the headlights are off, but when I turn them on, the right side of the trailer doesn't work.

Do you understand the "ground return" thing that J Martin was talking about?

Thanks for your help! I'll definitely dig into this on saturday starting from square one. So you think there's still an issue in the car somewhere huh...

damn. lol. Just had the machanic out on Thursday fixing the car ground issue with the brake light.

again, thanks for your help and time!!!

 

[nlain]

Re: still trying to figure out my wiring issue....

The ground return, what goes out must be able to come back, think of wires as roads, 12 volts out on the brown wire must be able to return on the white wire, 12 volts out on the green wire must be able to return on the white wire, 12 volts out on the yellow wire must be able to return on the white wire, everybody has to come back home on the white wire, if the white wire does not work then the 12 volts out on the green wire, right turn signal, tries to find another road home which would be through the bulb and back down the brown wire until you block it with 12 volts out to the taillights, then you have no way for the 12 volts to return so the lights go out. I understand exactly what I said here, hope it makes sense to you.

Yes I feel that something is still not right in the car otherwise just the headlights coming on should not have any effect on the trailer. There could still be a problem with the trailer as well, that is why I went in the check everything 1 step at a time and see when something odd happens, like the test light lights on the ground wire. Now on the car you may find the ground wire to be black instead of white like on the trailer. I do still think there is a ground problem somewhere. Bad grounds do strange things.

 

[Sea18Horse]

Re: still trying to figure out my wiring issue....

Good advice ^^^. One thing I might add is make sure to ground your test light to a good ground on the car itself. If you have to use and extra long jumper wire fine. And verify that the ground location you have selected is good by going to the positive battery cable and make sure the test light lights. Don't trust a ground on the trailer because the trailer grounds are suspect. (If this has been covered above I apologise.) I also agree with the above advice. You need to begin at the beginning. Also verify that it is in fact the headlights coming on that kills the trailer lights and not the park lights coming on. It will make a difference in which direction your diagnostics will take. Heaven is in the details. I realize that a lot of people are just not naturally detail oriented but in the case of trouble shooting like this, one needs to be.

Cheers.....................Todd

 

[ngt]

Re: still trying to figure out my wiring issue....

Good advice ^^^. One thing I might add is make sure to ground your test light to a good ground on the car itself. If you have to use and extra long jumper wire fine. And verify that the ground location you have selected is good by going to the positive battery cable and make sure the test light lights. Don't trust a ground on the trailer because the trailer grounds are suspect. (If this has been covered above I apologise.) I also agree with the above advice. You need to begin at the beginning. Also verify that it is in fact the headlights coming on that kills the trailer lights and not the park lights coming on. It will make a difference in which direction your diagnostics will take. Heaven is in the details. I realize that a lot of people are just not naturally detail oriented but in the case of trouble shooting like this, one needs to be.

Cheers.....................Todd

I know trouble shooting, just not on cars. It's a whole other beast to me. Arcade cabinets, I can take it down to a bad resistor or cap or ground or psu or whatever, but on a car, I don't know where the "beginning" is. I can trouble shoot down to "what causes what" to see what switch or something causes the problem, but when it comes to finding wiring, I'm not sure where to look.

I've tested this with the parking brake on and off. It works with the parking brake on just fine, as long as the headlights are off. Even when the headlights are on, the LEFT side works perfectly. Blinker/brake/running light and everything. The right side, gets nothing. I turn the headlights off, and everything on both sides works perfectly, parking brake on and off.

Also, when the headlights are on, all lights on the car work normally. Left and right side. That wasn't the case until Thursday when my mechanic found a ground by the left tail light and unhooked it/ rehooked it up.

I don't know what changes in the tail lights when the headlights are on. So I don't know what exactly to look at. I know the brake lights are always on when your headlights are on. Is there a different ground for that effect? Would something not get ground return in the trailer because the headlights cause a constant 12v going to the tail lights? Again, that may not make sense at all, lol...but I'm new to cars and just tossing things out there. Adn why would it only effect half of the trailer.

I take the boat out just fine with all lights working "in the daytime", lol. I just want to be able to leave when it's dark and be able to drive home when it's dark.

Thank you very much for your help and time. Also just letting me bounce my random ideas off of someone. Even if it's just someone to say "that doesn't make sense." It's better to know than not know.

Also, thank you nlain for the in depth explanation. I get the main idea.

 

[nlain]

Re: still trying to figure out my wiring issue....

I have been out removing my floating dock before I fell apart on me just came in the house and checking boards. I you work on arcade games and cabinets you are familiar with electricity so it really does not matter if you are on 110 volts or 12 volts the basics are the same, color coding on the wires not necessarily so. Any way you cut it what goes out must come back. I really do not know what to tell you on your problem, it really does not make sense that just the headlights cause this problem, the only way I can figure it is still a bad ground and maybe when the headlights come on one of them is hunting a return path that somehow winds up in the right taillight on your trailer, I know you said the light is new but there still could be a ground problem on the right side of the trailer and for whatever reason the headlights find the problem. To just throw something out here, headlight ground bad, headlight circuit hunts ground and runs it through either the taillight circuit or the turn signal circuit and here I thing the T S circuit is the one and at the same time there is a defective ground on the right side of the trailer. I hope this helps.

 

[ngt]

Re: still trying to figure out my wiring issue....

thank you very much!

 

[Sea18Horse]

Re: still trying to figure out my wiring issue....

Hi ngt,
I think we have some nomenclature confusion here . When I say "park lights" I mean "tail lights" or "running lights". Must be a pacific NW thing . You must have a newer car with automatic headlights. No way to turn the park lights....er I mean tail lights on without the headlights coming on also and vice-versa.

First off, does your car have separate brake and turn signal bulbs? or do the brake and turn signals share a single bulb? If they are separate then there has to be a converter box in the car somewhere to convert the separate brake/turn signals of the car, to the combined brake/turn signals of the trailer. So you'll need to remember that for later.

So I would say "the beginning" would be connect your test light to a good ground on the car with a long jumper so you can reach both the battery and the trailer lights at the same time. Check to make sure the test light lights by touching the positive battery cable. Then with the headlights off and the right turn signal on, go to the right trailer light socket, (make sure it has the correct style of bulb, two filaments/two contacts on the base) check to make sure that the correct filament is blinking. remove the bulb and make sure you have power (blinking of course) at one of the contacts in the socket. Put the bulb back in, now turn the headlights on. Assuming all the right side trailer lights are now inoperative, remove the bulb again and make sure you still have blinking power on the same contact that you did before and that you now also have solid power on the other contact. if you don't then you need to backtrack back to the trailer light connector and into the car and see where power is lost. This is where the question of whether it has a converter or not comes into play.

If you do have power then the next thing to do is put the bulb back in and touch your test light to the base of the bulb and see if you have power there (this should be ground and so you should not). If you don't then you need to backprobe the tail light and turn signal wires and make sure you still have power at both (usually brown and green) with the bulb plugged in. If you do have power at the brown and green wires and no power at the base of the bulb then you have a bad bulb.

If you have power at the base of the bulb then the next thing to do is backprobe the ground wire coming out of the socket (usually white) and check for power. No power = a bad socket. If you have power then you need to trace the ground wire/path back to the trailer light connector and see where the power gets lost.

I prefer a dedicated ground wire from all trailer lights back to the trailer light connector. I don't trust the frame of the trailer. Too many places where connections can corrode and/or fail. Good luck

Cheers.................Todd

 

[ngt]

Re: still trying to figure out my wiring issue....

I went through and everything was fine as far as I could tell. Everything was 11.56v. I started trying some other things and accidentally blew a fuse to my tail lights in my car. Swapped the fuse and all back to where it was. I was getting kind of pissed, lol...couldn't find anything. Not sure about testing the grounds on the lights. I hope I was doing things right.

I did get it fixed though. Sort of....jimmy rigged it up. I ended up running a wire from the back bolt on the working Left light on the trailer to the back bolt on the Right tail light on the trailer. I figured if that one had ground and the other one needed it, I could just loop it over. Everything worked perfectly. Anything wrong with doing it this way? The right running light took a minute to come on, and then it just popped on. It came on right away when I turned the car on and off to test stuff.

Again, THANK YOU SO MUCH EVERYONE FOR YOUR HELP!!! I may have used an easy fix, but I did learn some stuff (what to do and what not to do).

THANKS!

 

[nlain]

Re: still trying to figure out my wiring issue....

Sound like you fixed the bad ground which is what you wanted to do. It may be that the trailer mfg was trying to use the trailer frame for the ground, not necessarily a good idea, or the ground wire for the right side has an open circuit, at least you have working lights and as long as you secured your wire so it does not get torn off I see nothing wrong with what you have done. Made the lights work.

 

[ngt]

Re: still trying to figure out my wiring issue....

It may be that the trailer mfg was trying to use the trailer frame for the ground, not necessarily a good idea,

yeah, the white wire from the car goes straight to a bolt on the trailer frame way up at the front. Then the lights hook to some metal that bolts to the pole and then down to the frame.

Is there a better way to run ground throughout the trailer?

Again, thank you!!

I talked to a guy on a car forum and he said sometimes grounds don't fail until under a bigger load. He said that was why the right side worked with the headlights off. Does that make sense?

 

[nlain]

Re: still trying to figure out my wiring issue....

The ideal ground set up would be every light has a ground wire attached, one ground run from the tail lights down each frame rail and connected to each side marker light then you can attach those wires to the stud with the current ground wire. Somewhere in that light mounted to a bracket that bolts to the pole and the pole mounted to the trailer you are losing ground on the right rear and your wire across the trailer has bypassed that problem and completed the ground circuit for all the lights on that side of the trailer at least for the present time.

Ground failure can occur for a number of reasons, not connected properly, loose, corrosion, wires damaged, then if some or all of these conditions are there a heavy load could cause it to fail, they don't just because of a heavy load.