Trailer Lights driving me mad

[ThePerchik]

Hi,

I have a practically new Karavan trailer. I have a 4 pin connection on my highlander. Last time towing home I noticed that the right side turn signal was not working on the trailer. Hitting the brakes would light up the box and would change the brightness when the head lights were on. So it looked like one coil on the two coil bulb may have gone to crap or something.

I came home and unscrewed the light from the trailer, opened it up. There are two bulbs in there. A small bulb that has two coils. And a very small bulb that seems to slide in. The pulled out the bulb with two coils. I tested it and one coil would not light. I popped in a new bulb and now both back lights on both sides will not illuminate under and conditions. The two orange lights at the front of the trailer are still working.

I put on of those small LED testers into the plug on my car and all works fine. After reading the forum i figured it is most certainly a grounding issues. BUT, the trailer is not wired to groud and each light has a ground wire going directly into the light.

Does anyone have any ideas?

 

[Silvertip]

Re: Trailer Lights driving me mad

Take a very close look at the little nubs on the brass shell of the bulb. You will notice that one is positioned higher than the other. The socket the bulb goes into is built to match that different alignment so you cannot (or at least shouldn't) be able to insert the bulb the wrong way. However, the sockets are made so sloppy that you can actually get the bulb in 180 degrees wrong. I think that's what you've done.

 

[ThePerchik]

Re: Trailer Lights driving me mad

I noticed that the little points were on different levels. I did make sure to insert it the right way.

But even if i did insert it the wrong way, i am not sure what the issue would be, why would it cut out the other side?

 

[Fisherdave67]

Re: Trailer Lights driving me mad

Are you saying that near the tounge of the trailer one of the wires coming from the four prong is not grounded to the trailer?

 

[ThePerchik]

Re: Trailer Lights driving me mad

The ground from the socket on my car is not connected to the actual trailer frame anywhere. So if you touch the ground wire on the socket on the actual trailer and the trailer frame with the tester there is no signal. BUT, each of the lights has a ground wire going into it so they are grounded.

 

[mark_gober]

Re: Trailer Lights driving me mad

I'm with FisherDave. I'm questioning the ground at the trailer side. Certainly the car side connector is grounded. But what about the pin on the trailer side. If each light has it's own ground, how is the trailer getting grounded to the vehicle. (and please don't say through the ball, that might work with a new trailer, but will likely cause you much problems down the road) On my trailer, I landed a screw and a ground right on the tongue and put the pin on the trailer side right there.

One other option might be the bulb. Plug your original one in and see if you get your original symptoms back. I've seen very strange problems occur when the wrong style/type of bulb is inserted into the plug.

Mark

 

[ThePerchik]

Re: Trailer Lights driving me mad

All the grounds into the lights seem to be split off the ground from the 4 pin connector. I have tried putting the original bulb in and both back lights are still dark. I think today, i will try to put the bulb in reverse, maybe I did put it in backwards. I will also try to ring the ground in the 4 pin connector to the ground in the rear light box and see if that shows a good signal.

 

[flycaster]

Re: Trailer Lights driving me mad

Disconnect your trailer from the towing vehicle, keeping the electrical wires attached. Check out the lights.
IF THEY DO NOT illuminate, you don't have a ground connection from the towing vehicle to the trailer frame. This will indicate to you that you need to make a GROUND connection from the trailer connector to the trailer frame.
After you verify that you have a GOOD ground, reply back with the symptoms and helpful hints should be forth coming.

 

[windsors03cobra]

Re: Trailer Lights driving me mad

Sounds like a ground issue all day, the tip of troubleshooting while the ball is disco'ed is a good one Thanks !

 

[Silvertip]

Re: Trailer Lights driving me mad

You definitely DO NOT need a trailer frame ground if the ground from each fixture on the trailer terminates at the white wire in the plug. All a trailer frame ground accomplishes is that it eliminates a bunch of white wire. Grounding each light to the trailer frame is no different than running a white wire from each fixture to the white wire in the plug. I too agree that this is probably a grounding issue, but I don't believe it is because there is not trailer frame ground.

 

[ThePerchik]

Re: Trailer Lights driving me mad

OK, so did some debugging today. I think the reason the bulb went on the practically new trailer is that there is a short. When i put one tester wire to the ground on the 4 pin connector on the trailer and the other tester wire to the pin next to the ground on the connector i get a tone. When i run a REALLY long wire from the ground on the 4 pin connector to the tester and then touch the other end of the tester to the ground and one of the two positive leads in the light i get a tone. So it seems that the ground and a positive wire are shorting on that side.

The four pin wire harness breaks into 8 wires. Of those eight, 2 go to the front orange lights, 3 go to the left and 3 to the right. It looks like the three that go down the left and right sides have some kind of connections between the tongue and the actual light. At the tongue the three wires are joined to eachother. At the actual light they are three totally separated wires and one is longer than the others. It is my guess that it is down the right side that there is a short at this connection.

How does the theory sound?

Also, how do i pull them out. I can probably disconnect the ground from the light, but the other two leads are permanently attached. Does this mean i am gonna have to cut them at the light at pull them out from the tongue?

 

[bruceb58]

Re: Trailer Lights driving me mad

So it seems that the ground and a positive wire are shorting on that side.

How does the theory sound?

You just measuring continuity through the bulbs so that isn't the problem.

 

[ThePerchik]

Re: Trailer Lights driving me mad

Hm... OK

So its a fresh day and I figure i explain the test cases that I tried yesterday. I tried hitting the ground pin in the connector on the trailer against the trailer and I got no signal. So the trailer frame isn't grounded, but this shouldn't be a problem since each light has its own ground wire.

Car hazards on:
With the light bulb out in the rear right NONE of the lights works, neither of the back lights and both up front orange lights. They are all dead with one exception. The #57 bulb in the rear light without the 1157 bulb pulses very dimly. As soon as i put the 1157 bulb in, the 57 bulb goes dark but the orange lights up front start flashing in sync with the hazards.

Nothing I could do actually made the rear lights flash or light up.

I would love to see an accurate wiring diagram for this connector and the actual trailer. The connector has 4 pins that connect to the car and 8 wires that come out. It looks like two wires go to the orange lights, and 3 wires run to each of the rear lights. But who knows what other splits are in the actual frame.....

I guessing to test for shorts I will pull all the bulbs and see if touching the ground pin to the next pin gives me a tone.

 

[ThePerchik]

Re: Trailer Lights driving me mad

You just measuring continuity through the bulbs so that isn't the problem.

So why does it only give me a tone when hitting the ground and the second pin. Shouldnt all the pins ring through the light bulbs then?

 

[freddyray21]

Re: Trailer Lights driving me mad

it should only have four wires coming out of the trailer connector end. The white is a ground and your setup seems it splits off into seperate grounds. The brown wire is a common for tail and marker lights. It sounds as if someone split that wire off too to run to the two tail lights and the marker lights. There will be a green wire and I always forget if that is the left turn and brake or right turn and brake, but in any even the other wire is yellow and goes to the other turn and brake whichever. when your park lights are on you should have continous 12v if you put your meter ground to white and the meter hot to the brown trailer wires. with one turn signal on ground still to white you should get a flashing 12 v to either the yellow or the green wire. change turn signals and the other wire will have a flashing 12 v. If you don't have that at the back of your trailer plug then something is amiss there and no sense going further. if you do then trace back. Each tail light will have three wires coming out. white is ground, brown is common and one will have a yellow and the other a green. Match the colors. Again the brown wire will be common and will split off somewhere to go to both tail lights for tail lights and marker lights. Green goes to one side and yellow to the other.

 

[mla2ofus]

Re: Trailer Lights driving me mad

Disconnect all the white wires from lites, connect the long test wire to the ground wire on tlr plug. Then check w/ tester to be certain you have a good ground path from the tlr plug to the end of each ground wire. I think you have a problem in the ground circuit(s). I prefer using the frame as a ground path and in the case of a tilt tlr a short wire connecting the the frame at the hinge point.
JMHO,
Mike

 

[ThePerchik]

Re: Trailer Lights driving me mad

Disconnect all the white wires from lites, connect the long test wire to the ground wire on tlr plug. Then check w/ tester to be certain you have a good ground path from the tlr plug to the end of each ground wire. I think you have a problem in the ground circuit(s). I prefer using the frame as a ground path and in the case of a tilt tlr a short wire connecting the the frame at the hinge point.
JMHO,
Mike

Yeah, i think this is the next step.

Thanks all for the help thus far. I will try to test tonight and report back.

 

[Silvertip]

Re: Trailer Lights driving me mad

You would have much better luck troubleshooting this with a simple battery charger and/or voltmeter. Plug in the battery charger and connect the ground lead to the ground pin on the trailer connector. (The trailer is disconnected from the car by the way!). Now put a nail in the positive lead of the charger and touch each of the other three pins. The appropriate lights should come on. Those that don't but should are the source of the problem. Obviously the turn signals won't flash but they should light the brighter of the two filaments. And just so you know, a short will not pop a bulb. It can't do that because a short implies the wire feeding the bulb is shorted before the bulb thus current can't reach it to pop it. Besides, the bulb operates on 12 volts so 12 volts won't pop it. Age and shock will however.

Brown wire in the harness is the running lights that operates the orange and red marker lights as well as the tail (running lights). The turn signals are yellow and green wires in the harness.

A wiring diagram for these very simple circuits is not necessary. Current from the car enters the brown wire on the trailer, splits into two circuits (one down each side) and connects to the orange and red marker lights and then passes on to the tail (running lights). Each light has a ground wire (white) from it (according to you) so current passes back to front of the trailer to the ground pin on the plug then to the car. With the one of the turn signals on, again current enters the plug and passes down the applicable side of the trailer to the rear dual filament bulb and then back on the white wire to the plug. Same for the other side. This is a really simple circuit and testing it with a buzzer is not a good technique -- which obviously has wasted a bunch of yoru time. A voltmeter would be a better choice. Follow the voltage until you lose it. That's where the trouble is.

 

[Mark_VTfisherman]

Re: Trailer Lights driving me mad

First: green is right and left is yellow, or should be.
Second: use the Ohms scale on your meter with the 4-way unplugged to check for continuity between ground and the other three 12V connections. With the bulbs in, you should have continuity in all of them. If not, then you know which wire to chase. If you do, then remove all the bulbs, and check continuity again. There should be no continuity. If there is, then you know which wire(s) to chase.
Third: many trailer lights have push-in connectors for the wires. These can get corroded, stray copper strands can cross to another contact, or they can simply not have adequate contact. That is another area to look at even if above solves the issue.
Fourth: if the trailer wiring has been modified with ScotchLoks, or crimp butt connectors, get some heat shrink tubes and a soldering iron and redo all the connections. I remove crimp-style connectors and cut new, clean wire and use new crimp connectors AND solder them, then heat-shrink over them.
Fifth: 4-way flats are a wear item. Occasional need for replacement is not uncommon.

OK- don't know how I missed Silvertip's response (just ahead of this one) that basically says the same thing. Sorry. Silvertip's advice will achieve what you need.

 

[Biggems]

Re: Trailer Lights driving me mad

Is this the diagram that you are looking for?

http://www.google.com/imgres?imgurl...5YmPBw&sa=X&oi=image_result&resnum=1&ct=image