Trailer lighting question

[wagnerz]

The bulb was burned out on trailer light and I went to Bass Pro Shops and bought a whole new kits because i figured that was cheaper and easier then trying to trace and fix the light. I put in the new kit. The kits just has the two rear lights, and the trailer had two running lights as well on the side. I connected both of those to the brown wire on each side.

When the running lights are off, both blinkers work, and the brake lights work just fine.

When the running lights are on, the running lights work on the back as well as the two side lights, both blinkers work, but only the left brake light turns on, and the right light turns completely off. Its odd that it does this because its a brand new kit.

Does anyone out there know what this could be or have any guidance as to where to check? I have a tester if I need to start poking around at things.

Thanks

 

[scott hamilton]

Re: Trailer lighting question

Make sure you have 12V between ground and running, blinker posts on vehicle plug. If thats fine and all other connections look good then you have a bad ground. The lights use the trailer frame for the ground. To confirm try shorting bare metal from the frame to the light mounting post and test.

 

[GA_Boater]

Re: Trailer lighting question

I would disconnect the two running lights and see if the lights work properly. If the lights work OK, hook up the running one at a time. and see if the problem follows a running light. One of them may have developed a short.

 

[Silvertip]

Re: Trailer lighting question

This may be hard to get your head around, but the blinkers use the same filament in a dual filament bulb that the brake lights do. When you step on the brakes, both of the "bright" filaments should light. When you turn on either the right or left turn signal, the bright filament on that particular side flashes because the turn signal flasher is doing the work. What I've seen a lot of, is dual filament bulbs are inserted incorrectly even though they are keyed to supposedly prevent that. The issue is that the sockets are made so sloppy that one can force the bulb in 180 degrees out of place. That is not likely the problem but worth checking. So the dimmer of the two fillaments on each light should be wired to the brown wire along with the marker lights. The left and right turn signals are the brighter of the two filaments and go to the yellow and green wires.

 

[M9.9]

Re: Trailer lighting question

I might add to the above comment, be sure to check the brake light on your vehicle 'right', is it on or off when the trailer brake light go's off?

"...When the running lights are on, the running lights work on the back as well as the two side lights, both blinkers work, but only the left brake light turns on, and the right light turns completely off..."

 

[smokeonthewater]

Re: Trailer lighting question

this is ABSOLUTELY a ground problem..... your trailer frame is not grounded properly.... that would be the white wire..... needs to supply a solid ground from the vehicle, through the connector, and to the trailer frame.... wanna test it? get sme jumper cables and make a solid connection through them from clean metal on vehicle frame to clean metal on the trailer.... your lights will work.

 

[Bondo]

Re: Trailer lighting question

Make sure you have 12V between ground and running, blinker posts on vehicle plug. If thats fine and all other connections look good then you have a bad ground. The lights use the trailer frame for the ground. To confirm try shorting bare metal from the frame to the light mounting post and test.

Ayuh,.... I Agree,... Fix the Ground, 'n you've fixed the problem...

 

[oregoncruiser]

Re: Trailer lighting question

+2, ground problem. 99% of quirky light problems, especially on a boat trailer will be solved with a dedicated ground wire from the tow vehicle, through the plug and attached to the trailer frame.

 

[kenmyfam]

Re: Trailer lighting question

3 biggest issues with trailer lights.
1. Bad Ground
2. Bad Ground.
3. Bad Ground.

 

[M9.9]

Re: Trailer lighting question

The interesting part of the his problem was only one light, ie 1 of 2 Brake lights went out. That leads me to consider something's shorted, as wouldn't a ground problem (and I agree 9/10 times it is a grnd prblm), stop lighting on both banks on the over draw v. grnd supply? Solder All Connections, its really the best way and as far as I know and use, it never depends on a traliler through Ball--hitch ground--ever.

 

[smokeonthewater]

Re: Trailer lighting question

whoops... this question comes up so often that I didn't read it fully.... It's STILL a ground problem but it is only the ground on the light that isn't working correctly.... either in the fixture or between it and the trailer

 

[GA_Boater]

Re: Trailer lighting question

Except a few weeks ago a poster had a problem and never checked the bulbs after being asked several times. I think both were popped. At least he came back and updated. Took about 2 weeks for that one. But grounds 99.5% of the time.

 

[oops!]

Re: Trailer lighting question

3 biggest issues with trailer lights.
1. Bad Ground
2. Bad Ground.
3. Bad Ground.

Gee I hate it when someone beats around the bush !

 

[kenmyfam]

Re: Trailer lighting question

Except a few weeks ago a poster had a problem and never checked the bulbs after being asked several times. I think both were popped. At least he came back and updated. Took about 2 weeks for that one. But grounds 99.5% of the time.

OK I will concede the blown bulb thing but if it takes 2 weeks of other checks to get around to seeing if there are blown filaments then I would question whether it is a wise idea to let them loose with tools. Wonder what they do when a bulb expires in their home ???:facepalm:

 

[wagnerz]

Re: Trailer lighting question

Dang you Iboat people... You are always right. The spot where the ground connected had just a little bit of rust, that I thought was no big deal. Cleaned off the rust and connected the ground again, and everything works. Weird why it would only cause one function to not work.

 

[bruceb58]

Re: Trailer lighting question

Weird why it would only cause one function to not work.

Was getting a sneak path ground through the rest of the circuit.

 

[smokeonthewater]

Re: Trailer lighting question

or to explain it for you... the bulb has 2 filaments with 3 connections they have separate positives but use the same negative.... when the tail lights were off and the brake lights were on the current traveled through one filament to the shared negative, back through the other filament, through the tail light wiring and through all the tail lights and markers on the trailer and the vehicle to their good ground.... it caused the tail filament to glow in the light with the bad ground but since the current was then shared bu all the others in parallel it was not enough to make them glow..... when you turned on the tail lights that (limited) ground path became positive and since the bad light now had two positives and no ground it went out

 

[bruceb58]

Re: Trailer lighting question

Good explanation!

 

[smokeonthewater]

Re: Trailer lighting question

Good explanation!

thanx

 

[kenmyfam]

Re: Trailer lighting question

or to explain it for you... the bulb has 2 filaments with 3 connections they have separate positives but use the same negative.... when the tail lights were off and the brake lights were on the current traveled through one filament to the shared negative, back through the other filament, through the tail light wiring and through all the tail lights and markers on the trailer and the vehicle to their good ground.... it caused the tail filament to glow in the light with the bad ground but since the current was then shared bu all the others in parallel it was not enough to make them glow..... when you turned on the tail lights that (limited) ground path became positive and since the bad light now had two positives and no ground it went out

Very good explanation
Mine was a "little" more direct !!!!