Hello :-)

Finished installing new LED lights on my trailer the other day. Standard flat 4 connection. They worked fine until I turned on the headlights, which caused the turn signals to be very very weak on the trailer. It was hooked to my 1990 Subaru Legacy.

Earlier this summer I spliced a 5-wire to 4-wire converter (subies have separate brake lights, tail lights, and turn signals)into the Legacy wiring. It worked well with my old non-LED lighted trailer. My newly purchased used cat trailer shorted out a fuse, so I decided to replace the whole system with a LED kit.

So the LED wiring on the cat trailer worked fine when hooked up to my wife's car, a Subaru Forester w/ factory tow package. So I took the Legacy and cat trailer to an 'auto electric' shop and told them to fix it. When went to pick it up, it wasn't fixed at all. Looked exactly the same. I came back today, after they said they fixed it and it still looked the same (very very little intensity difference between turn signal flashing and not flashing, only when the headlights are on). The owner of the shop came out and swore it was normal, that he hooked the trailer to a different rig and it looked jusy the same.

So at 5pm, I took it home, hooked it up to a GMC van, Subaru Forester, and the Legacy. Worked fine on everything but the Legacy. Exactly the way it looked before taking it in.

What is the problem?? Besides picking the wrong shop to have work on it, I mean. For now, I'll keep the headlights off. I told the mechanics to replace the 5/4 adapter, if needed. But since they saw no problem, they didn't try replacing it.

Cheers,
Danno

I suffered a miriad of problems when I converted over to L.E.D.s on my trailer. Turn signals were terribly faint and running lights were strange. However, the problem turned out that I wasn't getting ~quite~ enough voltage to the LEDs. Apparently there is some internal circuitry in the LED units that has to have perfect voltage from a very good working 3 way adapter (for those with separate turn signal/brake lights) and mine was not. After a trip to Walmart, $15 later, I had a universal adapter that I soldered inplace of the previous unit on my truck and my new LEDs work perfectly and are brighter than ever.

If you want to test the units that you have, remove them from the trailer and connect the wires directly to the battery on your car. Simulate the turn signal by manually touching the positive terminal of your battery to the appropriate wire. Bottom line = they SHOULD work like you think they should and are blindingly bright when working properly and blinking.

Thanks, Jake.

I could bypass the wires that lead from the internal (car) signal wiring by usint a battery as you said. I'd test the 5/4 adapter box by disconnecting it from the car, then touching the wires as you said. So for turn signal with tail (head) lights, I'd touch those 2 wires.

If something doesn't work right, it's the box. If everything works fine, it's the car wiring. Let's hope for the box to be faulty. Not sure what I'd do if the car wiring were the problem.

Cheers,
Danno

Danno,

I just recalled that, while I did have a problem with my converter box, that I was also suffering a voltage drop through my old crusty trailer wiring. The old incandescent lights worked fine but were a little dim. I had just replaced my converter and still couldn't get the LEDs to function properly. They flashed but it wasn't all the lights and it went from dim to dimmer (or something like that). The side markers, which are separate LEDs on these, also didn't function properly. I tested them by touching battery terminals and they worked fine.

In my case, I had already planned to redo all the trailer wiring anyway since I had suffered a couple of shorts over time and I did that afternoon - soldering, applying sealant, and shrink wrapping every connection as I went. They work perfectly after that. They are nearly blindingly bright at night.

Jake:

In the new kit was both new lights and new wiring. I'm sure wires on the trailer aren't the problem. I'll let you know if/when I get it fingered out.

Ciao,
Danno

If you have a voltmeter, check the input and output voltage for the brake lights at the converter box. If there is more than 0.5 volts drop across the box, you may want to look at replacing the converter.

A good converter will have about a 0.1 volt drop and a poor one about a 1.0 volt drop.

All converters are not the same. The dealers and places like U-Haul usually have very good ones. Places like Walmart usually have good to poor ones. Depends on who was offering the best price.

Anouther problem is actual connection to the cars wiring. If you used those little blue plastic splice things, the connection is probably corroded.

By the way I hate trailers, trailer lights, and the wiring for trailer lights on my car. The people who build those things are always trying to save $0.02 which ends up costing me $10.00 2 years later.

We all know the deal, you discover the U bolts on your galvenized trailer are zinc plated and when one breaks you have to use your mainsheet and a roll of duct tape to hold the trailer togather to get home.

Thats right, if you can't duck it, [email]F@ck[/email] it, its broke!

Thanks, Carl.

I used wire nuts inside the trunk to splice, not the kind that looks like a wire guillotine.

Great info about the voltage drop and boxes :-)

Cheers,
Dan

Most of the adapter's I've seen for adding a trailer wiring harness, and put on my own vehicles just plug in between the tail lights and the rest of the vehicle. I've never owned a purely Japanese vehicle so I'm not sure how that works.

I'm wondering if there isn't a positive and a ground flipped around somewhere in the car where you spliced in? LED's don't work like a normal DC mono filament bulb where the two are interchangeable, juice will only flow one way through an LED. Could be that power is leaching through somewhere else in the fixture if it its a cheap one and that is the little bit of light that you are seeing. Not sure though. Like Carl said, check it with a voltmeter.


Really? f*cking wire nuts? Dude, solder it, heat shrink it, tape it. Wire nuts are only slightly better than the quick splice connectors. Its kinda like crapping your pants with a nice solid BM, or with the runs. Either way, you've just crapped your pants.

The thing that I learned about LED's is that you need a good, solid ground on each of the lights. If your ground isn't great then they wont work worth ****.

You do realize you're responding to an 8 year old post that was randomly bumped to the top by spam?

Well I do now....

Apparently there is some internal circuitry in the LED units that has to have perfect voltage from a very good working 3 way adapter (for those with separate turn signal/brake lights) and mine was not. After a trip to Walmart, $15 later, I had a universal adapter that I soldered inplace of the previous unit on my truck and my new LEDs led strip lighting
led strip lighting outdoor
12v led light bars
work perfectly and are brighter than ever.