Frustrating electrical snafu

[hauntedwinter]

Greetings everyone,
I just recently purchased a Harbor freight utility trailer. Have to assemble yourself. Everything went together great EXCEPT one thing. My lights are all messed up. I wired it exactly the way the directions said. Went to plug it in and noticed the plug was different then what was on the truck. Ok. Put new plug in truck and connected the 2 together. Here is where it gets interesting. Turn on driving lights and they work but as soon as I hit the brakes, lights go out. Ok. Figured it was a grounding problem. Created a new ground to bare metal on both the truck and the trailer. Try it again and still does it. I decided to try the turn signals. Put on the right directional and BOTH will blink on the trailer (while driving lights are on). In between blinks, they go out completely. Tried the left directional and did the same thing. Turn off driving lights and still did it. Rechecked the ground connectors and are securely fastened. Went to wally world and got 2 new plugs for the truck and trailer. Still does it. I have no idea whats going on. So, I decided to hard wire directly into each tail lamp. Yellow and brown wires to the left and green to the right and left the ground where it is. Used my multimeter to find the right wires for each one and tried again and it still does it!!! On the trailer, the green and brown wires go to the right side and the yellow and same brown wire go to the left.

Is it possible that one or both of the light assemblies are bad and allowing current to flow back through the brown wire to the opposite side??? Any help would be greatly appreciated!!!

[Shadow Catcher]

The first step is to find out if what is coming from the truck is working correctly, brake light converters go bad frequently, about six or seven dollars for a tester or use your meter.
Ditch the ground to the frame idea and run a ground wire, if it is not bad now it will be.
Easy enough to check to see if you have continuity/short problems

[hauntedwinter]

Hi Shadow,
I have checked the continuity from the trailer coupler to the frame of the truck with the trailer disconnected and all but the ground disconnected and was good. I am assuming that the ground will suffice for now until I figure this problem out. What else can I check? Also, I checked the power to the plug on the truck with the trailer unplugged. I am getting power to all the prongs in the way it should be. Example: Yellow will fluctuate power readings when the left directional is on and same with the Green wire when the right directional is on. When the brakes are applied, both yellow and green keep steady voltage. When driving lights are on, got steady power to the brown wire. I checked the brown wire while I had directional on and it was steady. The prob has to be in the trailer?

[Treeview]

Did you transpose the right and left tail lights?

Joke

Using a multimeter or test light start checking the signals at the vehicle plug, I think that you did. Then at the ends of the four wires that feed the trailer lights before you connect the lights.

Look to see that the wires are in the right order on the trailer plug. I can't imagine that they would be molded on out of order...but who knows?????

Do you have a good ground on the trailer too?

Tom

[hauntedwinter]

Hi Tree,
I have a good ground on the tonque of the trailer to the frame of the truck. I am starting to doubt the ground through the tail lamps though the more I think about it. The bolts holding the tail lamp brackets are suppose to be the ground to the frame. I think I will have to do a continuity test real quick..Be back shortly...

[hauntedwinter]

ok, I am getting resistance from the tail lamp bolts to the trailer. I suspect that may be the problem. I think I will run ground wires from each lamp to the white ground on the tongue and see what happens..

[parnold]

HW. I bought a little tester at Walmart. I think it was about 5 bucks. It has leds to indicate each circuit. Get one of those and check that the truck is putting out what it is supposed to before you drive yourself nuts.

One problem I found personally with the tester though, since leds draw so little power, I didn't discover the faulty wiring in my car until much later. I had a connector that worked fine under small load (led tester) but when it had the full power of the actual lights through it, the connection broke. It was one of those crimpy things where you connect two wires together without cutting, splicing, or soldering. Needless to say, splicing and soldering solved my mysterious problem.

Since you said you had to replace the plug on the truck, I would go with the assumption that the fault lies somewhere in the truck.

Good luck.. hope you have plenty of hair, you're likely to be pulling some of it out.

[Treeview]

Those 'crimpy things' shouldn't be used for anything permanent. having wire nuts and dielectric silicone is a step up. Solder and shrink tube is the best.

I've never had run an extra ground wire from taillights. Try cleaning the mounting holes or under the nuts. Cover with a dollop of dielectric silicone or dielectric grease. Of course, running a ground wire from the tow vehicle back is the most sure way of having a ground.

[Dale M.]

Those 'crimpy things' shouldn't be used for anything permanent. having wire nuts and dielectric silicone is a step up. Solder and shrink tube is the best.

I've never had run an extra ground wire from taillights. Try cleaning the mounting holes or under the nuts. Cover with a dollop of dielectric silicone or dielectric grease. Of course, running a ground wire from the tow vehicle back is the most sure way of having a ground.

WIRE NUTS are NOT THE SOLUTION the are usually the problem...

Crimp Connectors ( done properly) are the answer along with dielectric grease...

About grounding at tail lights... Yes they usually ground through bolt to chassis, you need to have a bare metal contact surface at bolts (scrape paint off) also all "joints" in assembly is painted.. none are good conductors... Running total wired ground to all lights may be solution...

As for wiring....

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

Remember wire colors are for people, electrons are colorblind... Wire for function (purpose) not for color match...

Something like this can be your best friend...



Dale

[Treeview]

These are the 'crimpy things' that are the source of a lot of electrical problems on vehicles:

http://www.amazon.com/3M-Scotchlok-Inst ... B0000AZ9H9

These are a better solution:

http://www.repairconnector.com/products ... -Pack.html

Solder and shrink wrap has always been the most durable.

I've had really good success using wire nuts with dielectric silicone to glue everything together....your mileage may vary. When I have had failures I can't remember it being one of my connections. It's usually where the wires come out of lights because the lights are cheap and don't have any sort of strain reliever.

[Goatdog]

Went thru this recently with my CT conversion. My 5x8 came with a flat four, my 4Runner had a seven pin. I decided to switch the trailer to a seven pin instead of using an adapter. Why? because I wanted to use the hot wire coming off the tow vehicle to recharge my CT battery.

I matched the yellow from the new seven pin I was splicing in with the yellow from the CT. I did the same with the other colors. I
had your exact results and a couple hours of frustration.

Turns out that the colors from the trailer wiring harness had not followed the norm (yellow left, green right) and whoever originally wired it had either been completely colorblind or didn't care. My guess is the latter.

It took me a while to figure out what colors worked with the trailers haphazard setup but I got er done.

I bought the trailer brand new in September.

[bobhenry]

Been there !

Do you want the answer ?

Like to drove me nuts and I have wired several hundred car/trailer combos in my 2 years as a U haul center manager.

What I had to do was add a ground wire to the outside of the bulb socket.
In the stock wiring design there is a problem with the socket barrel not getting a good ground. To eliminate the problem I added a white wire and placed it on the socket barrel and secured it with a worm drive mini clamp ( like a radiator hose clamp only smaller). I did this to both sides and ran the now hardwired ground back to the tongue to a common ground bolt. I went one step further in that all my trailers are set up so I can clip a lead from a tow vehicle ground to the afore mentioned common ground bolt on the trailer tongue.

99.9% of all trailer light problems are bad grounds especially if they are lighting and disappearing.

I would like to offer a bit of advice to all new builders...... HARD WIRE GROUND EVERYTHING. Do not rely on the frame as the return path.
It will save you a ton of on the road misery.

After you have tried this if I am full of S^$%#T let me know!
If it works let the rest know!

[Treeview]

Plumbing leaks=pile of water on the ground

Electrical leaks=clouds of invisible electrons in the air

Without tools/multimeter or really good logic or problem-solving skills electrical leaks are difficult to plug.

Hardwired grounds is a great idea!

Tom

[aggie79]

As others have said, on my HF utility trailer, I ran individual grounds to each light from the get-go. For connectors, I did use the marine-type crimp connectors that have heatshrink integrated in the connectors. I've never had any problems with lighting.

[hauntedwinter]

Hi everyone,
I did run individual ground wires from the lamp brackets on each side all the up to the white ground wire where it is screwed into the tongue of the trailer. Everything works awesome now. Thanks to all of you!!