Basic wiring help

[kmagill]

I'm ready to wire my teardrop marker and tail lights (and license plate light). My tow vehicle has a flat 4 pole connection so I have the matching connection for the trailer and about 20 feet of 4-wire. From looking at basic diagrams it looks like I need to splice into the brown wire in order to run brown down each side of the trailer. Green runs right side and yellow runs left. My question is regarding the markers (front and rear). The diagrams seem to indicate the markers only connecting to brown wire. Do I need to ground the markers to complete the circuit? Otherwise I think I have it figured out.
Thanks
Kyle

[eamarquardt]

Four wires, four connections.

Not sure what the color code is but you can figure that out.

Wire "A" - Ground, connects to all lights on your trailer on the ground side of the bulb
Wire "B" - Right turn/brake
Wire "C" - Left turn/brake
Wire "D" - tail lights, marker lights, any light you want on when your headlights/parking lights are switched on

Hope this helps.

Cheers,

Gus

[Dale M.]

Always found this site to be a lot of help....

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

BUT it assumes your marker lights and stop/turn lamp holders are mounted and grounded to metal chassis of trailer (note ground connection to chassis near plug in diagram) ..... BUT this is not always the case, you probably will have to extend the 'ground' wire to all lamp holders to get fully functional lamps..

Dale

[kmagill]

This helps, thanks. What has thrown me is the ground. The diagram I have been looking at (linked below) are for utility or boat trailers and show the white wire grounded to the frame. The lights in the diagram are attached directly to the frame as well so they are grounded. Because my lights are not connected to the frame my plan is to run the bonded 4 wire all the way around the trailer (interior) tapping in appropriately for each light.
The color code for my system would be...
Marker lights and license plate light - white (ground) and brown connected to the light
Right tail light - green and brown to the light and white to the mounting screw to ground
Left tail light - yellow and brown to the light and white to the mounting screw to ground

This is the diagram I've been looking at http://www.accessconnect.com/trailer_wiring_diagram.htm

Does this make sense?
Thanks

[eamarquardt]

That'll work. Don't bother with attaching your ground wire to the frame. No need if you wire each light to a wire leading back to your vehicles "ground". In theory, using the frame for a ground conductor is fine but as steel rusts the connections need to be maintained which rarely happens. If you run a wire ground to each light you'll be way ahead in the long run.

Cheers,

Gus

[kmagill]

Great. Thanks for that.
K

[kmagill]

So I have all my lights connected...
2 front side markers (amber)
2 rear side markers (red)
1 plate holder with light
2 3 way tail lights (running, stop, turn)
Everything is working fine EXCEPT when the headlights are on on the tow vehicle so that all the trailer lights are illuminated I lose the turn signal function on the trailer. Any suggestions on how to fix this?
Thank you.
K

[Dale M.]

Stop/turn signal function should be on separate filament of bulb from the marker/tail lamp circuit... Sounds like you have something crosses in wiring scheme and its feeding back in to turn signal circuit...

A lot depends on how tow vehicle connector is wired...... Some vehicles use a separate filament in bulbs (3 total) for each function and if you try to wire it to a two filament bulb you need some sort of a converter in tow vehicle to isolate the separate functions.... Before we can give a really good answer to you, we need to know how tow vehicle is wired... You probable should use test lamp and see if tow vehicle is actually wired correctly....

Dale

[kmagill]

Thanks Dale,
The tow vehicle is a 2007 Nissan Frontier. I have only towed very occasionally. I should mention that I had the hitch installed about 6 years ago by Uhaul. Their wiring job failed with 6 months. I discovered this on a dark night (not towing but lost tail lights). I had it repaired. That repair failed eventually. My local mechanic repaired it about 2 years ago. So there is a problematic history.
That said, I put the tester on it tonight (it is a Uhaul brand flat 4) and it all 3 poles functioned (running lights and left and right signals). I followed the wiring as far as I could under the vehicle and couldn't find any sign of a converter. I guess the problem does relate to my wiring of the trailer.

[Dale M.]

This site seem to say there is a converter or relays required to make 4 way connector function correctly... Further research may be necessary...

http://www.etrailer.com/t1-2007_Nissan_Frontier.htm

http://www.etrailer.com/Custom-Fit-Vehi ... 0071175007

First option would be to test functions on tow vehicle to be sure it functions properly before you blame yourself for your wiring in trailer....

My first though would be with history on your vehicle, this tool would be first thing I would test with...

http://www.etrailer.com/Accessories-and ... 30512.html

Harbor Freight has them and probably most auto parts....

Dale

[kmagill]

Again, thanks Dale,
Going back to the original hitch installation at Uhaul, I recall the guy saying something like "I didn't have the right harness for your truck but I made it work". From watching the etrailer video and inspecting my truck I see there are no relays installed under the passenger side kick plate and it looks like the Uhaul guy cut off the factory connector under the back of the truck and hardwired his connector in place. I'll say it now, don't go to Uhaul for anything. Ever. This shoddy wiring installation along with another painful experience I had at Uhaul have finally convinced me. They are incompetent.
So now I am wondering, without the relays, has my trailer hitch wiring ever worked properly?

[kmagill]

As a follow up to my last post, I discovered that the tail lights on the trailer do flash very, very faintly when the running lights are on. The flash is barely perceptible.

[bobhenry]

As a follow up to my last post, I discovered that the tail lights on the trailer do flash very, very faintly when the running lights are on. The flash is barely perceptible.

Drag out your jumper cables and clip one end of either color to the trailer and clip the other end of the same color cable to the tow vehicle. I bet the trouble will immediatly disappear.

Make up a heavy 10 gage wire with 2 heavy duty alligator clips on the ends and clip one to each for the road. Troubles gone !


P.S. Let me know if I am right I am keeping score !

[kmagill]

Thanks bobhenry,
I had high hopes and expectations. I tried as you suggested but alas it did not work. I also spoke to the folks at eTrailer where I bought the lights and they suggested I ground my whole system to the trailer frame ( which I had not done from an earlier recommendation in this thread) but that also did not help. Not sure what to try next...

[kmagill]

SOLVED!
I reversed the wiring on the tail lights and it has solved the problem. Each tail light has a green and a black wire. Following the logic of the wiring color code I wired the lights green to green, black to brown (on the right side) and green to yellow, black to brown (on the left side). I just reversed that (green to brown) and they are working perfectly.