Screwed up the ground, I think.

[Oregon Brew]

Don't know why I don't understand this 12v stuff.

I brought my wiring connection - a pigtail - into a junction box. I connected each of the five wires to the appropriate knobs. I then ran four-way trailer wire plus a blue auxiliary wire to the back of the trailer. I ran a neutral (white) wire to both the tail lights. Now I get running lights all the time but no brake lights and no turn signals. I think the white wire must not be grounded to the frame. Don't know how to ground the lights, since they are mounted on the galley door, and that door is just plywood and aluminum. Can I ground them in series or something?

Clearly, this is not the same as wiring a house, where the white wires can all be hooked together. Help!

[eamarquardt]

There isn't enough detail in your post to allow me to figure out what is going on. That said, you can't rely on the color codes because not many outfits adhere to whatever the convention may be. So, you have to have a schematic (either drawn or in your head) and keep track of each wire and wire it to the right place.

Not sure about your nomenclature but in DC there is no "neutral". You have battery which is positive, switched, and is the supply for your bulbs and ground which is the return of the power to the battery's negative terminal. For a circuit to work you gotta have the power (brake light, tail light, brakes, etc) which is switched or controlled in the tow vehicle and a return path to your battery's negative terminal.

It's common practice to combine the ground conductors and run just one wire back to the battery but you can't combine positive leads and retain individual functions (brakes, tail lights, battery charge, etc.)

I'm kind of rambling but I hope I've cleared things up a bit. Just sort things out one at a time and only combine your ground leads. All other functions brakes, tail lights, brake/turn lights, battery charging, etc. must remain separate from each other.

Cheers,

Gus

[48Rob]

Don't know how to ground the lights, since they are mounted on the galley door, and that door is just plywood and aluminum.

For a tail light/brake/turn signal light fixture, there are two wires coming out of the fixture.
Both are positive.
One posititive supplies the tail light function.
The other positive supplies the brake light and turn signal function (brake and turn signal both work on the same single wire).

If there is a third wire, it is a negative, or ground wire, not many lamps have them.
Most often the lamp is attached to a metal surface that is tied to the metal chassis, but if it is not, you can run an extra wire to each lamp, and use the screw or bolt the lamp attaches to the body with as the connection point, or, run a jumper wire between the steel chassis, and the "floating" metal panel.
A wire from the chassis to the lamp is best.
If you have multiple lamps, one ground wire can be run, connecting all the lamps.
It is easy using an electric tester or meter to determine which wire supplies which function.
Turn on the tow car ignition, and choose a function, say right turn signal.
Place the ground lead of the tester on a good ground point, then test each wire until the test light blinks, or the meter display flashes between zero and 12.5 volts.
Mark the wire with its function, and then do left signal, then tail lights.
Often, even when the ground connections on the trailer are wired correctly,the ground is lost between the tow car and trailer (the tow ball is not meant to be the ground connection).
Be sure you have a dedicated wire that connects the tow car chassis, to the trailer chassis.
Better yet, is to have a wire that runs from the tow car battery, through the wire harness to the trailer chassis, and lamp body.

Rob

[len19070]

Does your Tow Vehicle have Yellow Turn Signals?

If so you need a Tail light converter.

http://www.reese-hitches.com/products/119130

Happy Trails

Len

[absolutsnwbrdr]

Does your Tow Vehicle have Yellow Turn Signals?

If so you need a Tail light converter.

http://www.reese-hitches.com/products/119130

Happy Trails

Len

They won't necessarily be yellow. My Subaru has red.

If the turn signals are separate from the break lights, then the converter is necessary.

[Dale M.]

A "typical" wiring diagram can be found here...

http://www.etrailer.com/faq-wiring.aspx

Lots of help here...

http://www.etrailer.com/faq-4-5-way-tro ... oting.aspx

As mentioned above... Many lamp assemblies expect to be mounted on grounded surface... Just because surface may be metal (hatch) does not mean it has a ground.....With some lamp fixtures it may be necessary to run dedicated ground wire to fixture.... Also at times lamps will search for a [missing] ground and cause it to illuminate with a false "current loop"... The missing grounds can drive you nuts... Sometimes a long wire with a couple of clips on each end is best tool as you can clip one end on known ground and touch other end to (shell) of fixture and lights may begin to operate properly... This is good indicator of missing ground...Also missing grounds are the hardest to locate because lamp indications are different than all known possibilities....

Dale

[Oregon Brew]

I used a standard 5-pin pigtail. Wires were labeled:

Green – Rt Turn,
Yellow – Lt Turn,
White – Ground,
Brown – Tail,
Blue – Auxilary.

I also bought a 20 length of commercial trailer wiring using the same color convention.

In a trailer junction box, I connected green to green, yellow to yellow, and so on.

The two tail-lights have three wires coming from each – Brown, green, and white.

From the junction box to the right tail light, I connected green to green, brown to brown and white to white.

From the junction box to the left tail light, I connected yellow to green (since the lights seem to be interchangeable), brown to brown and white to white.

The blue wire currently isn’t hooked up to anything.

As far as I know, the white wire is not grounded to the trailer body at all. When I get home tonight, I’ll run a wire from the J-box to somewhere steel on the trailer and see if that makes a difference.

Problem should not be in the tow vehicle because I had it professionally wired.

Am I missing something?

[eamarquardt]

Yes you are missing something. You can't trust that your "professionally wired" vehicle was wired correctly unless you have tested it with a known good trailer, a test device, or a test lamp.

You can't rely on the color coding to ensure success. You have to understand the function of each wire and connect it accordingly.

As a start, I'd test each of your trailer's circuits with power from a battery to ensure that each circuit works properly. Then I'd check each of the circuits from your tow vehicle to ensure they are getting the right output when the brakes are applied, the turn signals activated, and the running lights are turned on. This should help you determine what is taking place and make the needed corrections.

Hope this helps.

Cheers,

Gus

[bobhenry]

To eliminate the ground gremlins temporarly run a very long wire from the battery of the tow vehicle's negative post.

Connect this wire to the white wires of each light one at a time while energized. This will let you know if it is the missing ground connection.I think you will find it to be a floating ground. I took all my negative white wires to a common grounding block then a heavy white ground to the plug in pig tail. I also spliced in a ground wire that actually clamps onto the tow vehicle to give a positive ground connection. No light problems for 4+ years.

I have found that the harbor freight ( I have 2) frame mounted lights rely on a rather bad ground to the frame. I fought these gremlins until I added a white ground wire by trapping it under a worm style mini hose clamp and around the outer case of the brass light socket now all is well.

A seperate hard wired ground has proven to be far more reliable than a frame ground in my opinion.