Sort of fixed the lights- one problem, though

[Bobbie Mayer]

So I towed my trailer over to a friends to work on lights (I have no driveway; garage opens onto the street.) They were out when I left home, turn signals ON when I arrived, then intermittently went on and off, then off. Weird, weird, weird. We cleaned up the contacts on the 4 way plug and got the turn lights to be more reliable but one was brighter than the other. Went and bought a tester and new bulbs and figured out the tail light wire had a short (six inch) spliced section that was only intermittently working, so bypassed it and got the taillights to stay on. One (the opposite one) brighter than the other. So I look: the bulb has a thick filament and a thin one and they are connected on the left so the turn signal is the thick one (brighter) and on the right so the turn signal is the thin one (harder to see.)

It isn't obvious to me where this would have been reversed in the wiring. Anyone have any idea? I assume it is probably where the lights were connected to the wiring harness (which runs inside the trailer to the back.) These lights were originally set up for two bulbs (light and turn separately.)

Anyway, they work now, but one tail light is brighter which makes its turn signal hard to see.

[Brian B-P]

Originally Posted by Bobbie Mayer

... one tail light is brighter which makes its turn signal hard to see.

... and the brake light hard (perhaps impossible) to see, and confusing the brake and turn indications (one bright light when braking, looks like a turn), and the tail light (on the too bright side) annoying to following drivers.

The tail circuit is the one which goes to both tail lights - it ideally should be the same coloured wire at each side. It needs to connect to the dimmer (thinner) filaments of the bulbs.

[Bobbie Mayer]

I can understand that. I just don't know how to fix it as the wires disappear back into the trailer and I don't know where they were wired backwards. The way it comes off the car there is a green wire and a yellow wire, each to one light, and then a tail light wire. The light fixture itself does not have a place to connect wires- they are built into it and run into the trailer where, presumably, they were attached backwards to the wires coming from the car. Hmm, I guess I can pull them through a bit, cut them off, and splice them to each other if I can't see where they were put together backwards in the first place. It's possible I can see where they go inside the trailer- we looked at the other side but not the side that is wired backwards (this was the last thing we figured out before quitting.)

[calindor]

I know you want to fix the problem at the source, but what about fixing it at the socket itself. Are the wires crimped or soldered to the socket. Could you remove and reattach?

- edit -
re-reading your last post. "the light fixture itself does not have a place to connect wires- they are built into it and run into the trailer..." I guess I found the answer?

[Bobbie Mayer]

The wires just disappear into the socket base, nothing to wire there. But I do think that if there is enough loose wire I can just swap them out and splice them outside the trailer, inside the lens cover.

Oh, and the corner of the lens cover broke. Anyone know if you can get those types of covers? It's like an open-backed box that fits over the metal plate that holds the fixture and then screws into the back of the trailer. Roughly 5 inches square.

[mary and bob]

I have seen bulbs put in wrong, not real easy to do as the pins are staggered, but it can be done.

[Carol H]

Originally Posted by Bobbie Mayer

Oh, and the corner of the lens cover broke. Anyone know if you can get those types of covers? It's like an open-backed box that fits over the metal plate that holds the fixture and then screws into the back of the trailer. Roughly 5 inches square.

Bobbie, do you have a picture?

[Bobbie Mayer]

Pictures Here. The red cover sits about two inches off the back of the trailer (hard to see the 3-d in the picture. (Scroll about halfway down that thread.)

[Bobbie Mayer]

Originally Posted by mary and bob

I have seen bulbs put in wrong, not real easy to do as the pins are staggered, but it can be done.

The bulb is in right. I don't think it would fit wrong but maybe- but I checked that, anyway. Interesting I noted the weak turn signal on the above link- I just didn't realize why, then.

[Francesca Knowles]

Originally Posted by Bobbie Mayer

Pictures Here.

Is the black wire in this picture supposed to be ground, and is it "attached" at the near corner by means of the light's mounting screw? If so, I highly recommend connecting it instead to the trailer's ground wiring, since the fiberglass surface the light's attached to is a VERY poor choice for ground.

I had a similar lighting situation while out in the boonies, and the culprit proved to be exactly this, though in my case the lights were on an aluminum surface- surely slightly better for ground than fiberglass but inadequate nevertheless.

Installing a true groundwire solved the problem in my case.

Francesca

[RRJR]

I would buy new trail lights and start over.

[Bobbie Mayer]

Originally Posted by Francesca Knowles

Is the black wire in this picture supposed to be ground, and is it "attached" at the near corner by means of the light's mounting screw? If so, I highly recommend connecting it instead to the trailer's ground wiring, since the fiberglass surface the light's attached to is a VERY poor choice for ground.

I had a similar lighting situation while out in the boonies, and the culprit proved to be exactly this, though in my case the lights were on an aluminum surface- surely slightly better for ground than fiberglass but inadequate nevertheless.

Installing a true groundwire solved the problem in my case.

Francesca

It's apparently grounded via a wire on the back attached to the screw. That does not seem to be the problem (I originally thought it was.)

[Bobbie Mayer]

Starting all over was my original plan but it isn't that easy the way they are wired. And that would not have helped what turned out to be the problem with them shorting out.

However I am very tempted to get some trailer lights (prewired) and run the wiring harness under the frame and mount the lights on the bumper. I don't have 12V in the trailer (there are some light fixtures but no battery at the moment and no real good reason to fix them.) It would just be nice to have all the lighting accessible. Then the taillights on the trailer can be purely decorative.

[Steve Hilby]

Bobbie, you ought to be able to get to your wiring through a cupboard or under-bench storage bin. Once you do, it's simple; you just need to switch the two colored wires, one of which is taillight and one of which is brake light. I'd just cut them and resplice them together again, switching wires as I did.

[Francesca Knowles]

Originally Posted by Bobbie Mayer

Starting all over was my original plan but it isn't that easy the way they are wired. And that would not have helped what turned out to be the problem with them shorting out.

However I am very tempted to get some trailer lights (prewired) and run the wiring harness under the frame and mount the lights on the bumper. I don't have 12V in the trailer (there are some light fixtures but no battery at the moment and no real good reason to fix them.) It would just be nice to have all the lighting accessible. Then the taillights on the trailer can be purely decorative.

Your trailer's existing running lights would be purely decorative, too, though...

Francesca

[mary and bob]

In that picture I would say that the black wire is the ground and the bulb grounds through its base, through the socket which is attached to the light base plate, then through that black wire which is held on to the base plate by one of the mounting screws, and then that black wire completes the ground circuit, but to who knows where. So there are a few points where the ground connection can be lost. Probably the easiest way to check the ground circuit is with a separate piece of wire with bare ends, or better yet an alligator clip on each end. Take one end of the wire, touch it to the bulb socket, thereby eliminating the other points of lost connection, then clip the other end to where you know there is a good ground, such as the trailer frame, the other bulb socket or base plate assuming that light works OK, or to where the ground from your tow vehicle attaches to the trailer, most likely the trailer frame, but you will have to determine that. All this will tell you if there is a ground problem, which is the most common issue. I'm wondering how wires could have been reversed on the light if it is so hard to get at it. A simple test light makes light problems much easier to resolve. All these repairs are quite easy for me after working on big trucks and trailers for so long, but sometimes it's hard to explain just how to diagnose the problem to someone for whom it is just not their field of work. If you were closer I would gladly fix it for you.

[Bobbie Mayer]

The ground problem seems to be fixed. The problem now is the reversed wires. They are very obviously reversed as the right bulb works differently than the left one. I think it was installed wrong in the first place, most likely. (I never noticed before as my old car didn't have daytime running lights, so I was never testing both running light and turn signal at the same time.) I haven't had a chance to try to sort it out yet- it may be simple or it may be a hassle to get at, depending on where they are spliced in. The wires come out in the little cupboard under the wardrobe, but the door opens out towards the back door so to work on it really requires taking off the little cupboard door, minimum. I do have a test light and this time all I have to do is switch the two wires- and hopefully there will be enough extra to work with.

Once I get them all fixed I want to put LED bulbs in the fixtures.

[mary and bob]

I never liked to do this, but sometimes it was necessary to splice in an extra piece of wire, which of course made for more connections and more points of possible failure. Is it possible to pull off the whole tail light assembly and pull wires out there. Or can you put a new bulb socket in, or just the insert with the wires, drill through the light base and feed wires to the inside and splice them. And in the picture it looks like there are two bulb sockets?

[Bobbie Mayer]

The bulb socket apparently came prewired; there is no exposed place to solder or otherwise connect wires. This is an old light fixture from when tail and turn lights were two different bulbs. I'm not sure how two wires (from two bulbs) got connected to one bulb- seems odd to me even though I do understand how the two filaments in the single bulb works as two lights would have. It's possible at that point they took out a single-light socket and put in the dual purpose socket. Anyway, I don't know if I have enough wire to pull through or not. I hope I won't have to splice any- it was a splice like that that was causing the previous problem. We just figured out the wires were switched as we were putting the covers back on- no more time that day to work on it- and I won't get back to it before at the very least this weekend.

[Bobbie Mayer]

Looking at my own picture, I think I should be able to pull at least an inch of wire through, cut through both, and splice. But what I hope I can do is switch them at the other end of the fixture wires so that I don't have a new splice.