Other people have mentioned the tow vehicle ground. I have a question...
My tow vehicle has a factory installed connector in the wire harness for the trailer wiring. This cable and converter plugs right into that connector.
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With that setup do I need to be concerned about the vehicle ground or anything else related to the vehicle wiring? Is it (normally) safe to assume that the factory installed harness is properly wired?
I'm way ahead of you, Bob!
The lights were the last task in my periodic maintenance exercise. The tires are fine and inflated to proper pressure - including the spare, the wheel bearings were repacked, the hinges and other hardware were removed, wire wheeled and coated with RustOleum Cold Galvanizing Compound and the fenders were removed painted. While the trailer was on the jack stands I inspected the underside, the axle, etc. I checked the safety chains and their connection at the trailer. It all looks good.
Funny story about the jack. I've been using a wheeled jack for years. It sure makes it easy for me to move the trailer around in my driveway. A few years ago I found that after I swung the wheel down, it would hold the trailer up but as soon as I tried to move it, the jack would start to collapse. Turns out that the nut end of one of the carriage bolts that holds the jack to the pivot plate had sheared off and the part that was left just barely caught. It was fine while in the vertical or horizontal position, but as soon as any lateral force was put on the bolt, it shifted just enough to move out of the pivot plate and cause the jack to collapse. You couldn't tell that the bolt was sheared unless you stood directly over the jack and looked down into the space where carriage bolts came out of the back of the pivot plate. It all looked good from the outside. It's now one of the things I check on a regular basis.
So, now, the only thing left to deal with are the lights. My only real concern is the brightness of the tail lights. Rewiring has long been on my list of things to do, but if an LED upgrade will improve the tai lights, I'll be satisfied for now. I've got an 900 mile round trip to my daughter's college in a couple of days and don't have time to rewire the trailer before then. If the LED's are brighter with the existing wiring, then they'll already be there when I get around to the rewire.
So unless you have a new trailer, why not just replace the whole socket assembly. Sockets deteriorate over time. Some of the new lights are much nicer than putting a plug in bulb in. They over more leds so if one fails you still have others.
I spent some quality time with the trailer today and here's what I found.
First, the replacement 1157 LED bulbs didn't work very well. It's not that weren't they bright enough, the problem was the directionality. The socket inside the fixture is positioned such that the bulb "lays flat" as opposed to pointing straight out. The incandescent 1157 bulbs spread the light across the entire lens. The LED bulb acts more like a flashlight, only lighting up 1/4 of the lens in the direction it points. In fact, my wife thought the LED side was out until she stood directly behind the trailer. While the section that was lit was a little bit brighter than the incandescent, she said she would rather be following a trailer with the incandescent than the LED. I also tested it at night and about 3/4's of the lens was lit up, but there was still a dark void, unlike the incandescent who's lens was fully lit.
OK, so now I decided to look into the ground situation.
Just so you know what I'm working with, the trailer has the following set up:
- Six GE193 side markers, which are grounded via the screws that hold them into the trailer shell
- One GE193 license plate light, which is grounded via a pigtail to a self tapping screw into a trailer frame member.
- Two 1157 (dual filament) tail/blinker/stop lights. The left side is grounded via a pigtail to the same self tapping screw as the license plate light and the right side is grounded via a pigtail to a self tapping screw into a trailer frame member on the other side of the trailer.
- One 1156 (single filament) bulb for an interior light in a switched fixture which is grounded via a pigtail to the same self tapping screw as the right tail light.
The following tests were all done with the trailer disconnected from the tow vehicle hitch to eliminate the hitch connection from the equation. The only connection was the vehicle flat four to the trailer flat four. The vehicle flat four cable is attached to a factory installed connector in the vehicle's wiring harness and uses this cable and converter:
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When I started testing, I had removed the LED bulbs and the tail light sockets were empty. The side markers, license and interior bulbs were all installed.
The first thing I did was disconnect the ground wire that went from the trailer's flat four to the trailer's tongue, removing the trailer's frame as the ground. I ran a dedicated ground wire from the trailer's flat four to one of the rear tail light assemblies. When I turned the tow vehicle lights on, the voltage read 12.85 V at that tail light. Obviously, no lights came on because there was no bulb in the tail light socket and the rest of the lights had no ground.
I then ran a pigtail from the tail light's ground to the ground screw at the rear of the trailer that normally supplies the ground for that tail light and the license plate light. That screw goes into the frame of the trailer. When I did that, the side markers and license plate lights came on and the voltage at the tail light dropped to about 11 volts. When I inserted the tail light bulbs, the voltage dropped to the 9.5 V that I had been reading without the dedicated ground.
That tells me that whether I use a dedicated ground from the flat floor to the tail lights or use the frame as the ground path, I'm still going to get that voltage drop.
I then ran a dedicated ground directly from the battery's negative terminal to the tail light. There was no improvement. 12.85 volts with no bulb in the tail light socket and the rest of the trailer not grounded. As soon as I added a pigtail to the trailer frame, the voltage dropped almost 2 volts. Then when I put the tail light bulbs back in, I was down to the 9.5 level.
I went around the trailer pulling side marker bulbs and each time I pulled a bulb the voltage at the tail light went up by 0.2 - 0.5 volts. It was not consistent which tells me that each bulb was drawing a slightly different amount of current.
I think the next test is going to be to start running dedicated grounds to each fixture and see what happens. Since each fixture that uses the trailer frame as ground added to the voltage drop, there doesn't seem be a single cause for the drop, i.e. it's not one bad fixture causing the problem.
Heck, as long as I'm running all those grounds, I might as well just rewire the whole trailer. Running the extra ground wire to the side markers won't be that hard, but since the current ones are single wire fixtures with self tapping screws, I'll either need to use a nut, bolt and lug for the ground or replace the side markers with 2 wire fixtures.
I just wish I knew before I started rewiring whether or not a dedicated ground to each fixture is really going to resolve the voltage drop issue. Running a temporary ground wire is as much a pain as rewiring since there is really is no good way to attach the ground to the current side markers unless I make up bunch of clip leads and clip the ground to the ground bracket on the housing.
Maybe I should just do all my driving at night. The lights are easy enough to see when it's dark.
I doubt the ground is the problem, given the tests you have done. What is the voltage from the tail-light connection to ground when the lights are lit? If it is 9.5 volts, the problem is in the tow vehicle wiring. Use voltmeter from the connected trailer plug to the tail-light on the car. If over 1 volt (I like to see less than .2) the problem is in the trailer wiring connections. If voltage at the tow vehicle tail light is also low with the trailer connected it is a problem with the main tow vehicle wiring.
You have just demonstrated why a lot of these after market lamp replacements, particularly LEDS are not certified for use on the road in most counties of the world.
On top of that at least some countries require WIRE ground connections back to the vehicle . The tow ball is not accepted as a connection.
I doubt adding wire grounds will fix the problem. As I see it you still have a single bad connection and every lamp you add increases the drop. You should be able to measure the drop across each connection (less than a volt) then one of them will be higer and you have got your culprit.
Please clarify what you mean by "use a voltmeter from the connected trailer plug to the tail light on the car".
From what pin on the trailer plug? To what on the tail light on the car?
And if the problem is with the tow vehicle wiring, what is the problem? What would I be looking for if the voltage you want me to check is over 1 volt?
try connecting a positive wire to a positive socket connection for he tail light .....
your problem is likely a bad plug assembly, a direct connection from the ba ttery positive should brighten things.....
in fact the one connection will likely brighten all lights
trailer plugs are cheap, you could make up a test plug with light bulbs, an d plug it into the tow vehicle......
or make up a test tow vehicle end connection to power the trailer, add a sw itch or two to duplicate brake lights etc
but i would still suggest rewiring the total trailer, you will find trouble s, corroded contacts, poor connections, and in the case of one trailer i wo rked on the main traler wire insulation was badly worn, in a hidden area it would of shorted and taken out all trailer lights..... found when pulling new cable.
if you rewire go at least one size heavier......
if the wire is 16 gauge, go to 14 gauge, it will be stiffer, but work bette r...... of course use straded
the last trailer i worked on, the trailers plug assembly connected inside a small metal box on the frame. taking the cover off revealed its backside w as rotted out, allowing water coirrosion of the connections....'the damage wasdnt visible from the outside
you should seal all crimps with blobs of silicone caulk all around every co nnection so water cant get at them....
Hmm. Souns like a inadquate wire size or poor connections; crimping, screwed down with star washer, rust causing poor conductivity, etc. I don't know how old the trailer is. When I had my fiver, I used to inspect wiring at start of every camping season. if something is ??? I remedied it. And LED needs good diffuser lens, reflector to be effective. LEDs comein many different forms, shapes, specs.
Thanks for the suggestions. The most that will happen this week will be a possible test with an external 12 V source, or perhaps a different tow vehicle if I can get someone with a flat four connector to stop over. That would at least eliminate my tow vehicle as the issue.
The trip to my daughter's college is on Wednesday and as long as everything is working at this point, I'm not messing with any wiring on the trailer or tow vehicle so soon before the trip.
From the wire that feeds your taillights at the plug to any of your tail-lights on the tow vehicle. You want to do a "voltage drop" test. It will show if there is resistance between where the tow vehicle tailights get their power and where the trailer gets it's power - which boils down to the adapter wiring. If you have no voltage drop there, check the voltage from ground to the tow vehicle tail light - if the voltage is low there, you have bad wiring or a bad switch in the tow vehicle.
On MOST cars without a trailer towing package, you are smart to install a relay box (or electronic equivalent)) and feed it with a #6 wire from the battery (fused) and have the tail lights, signals, and brake lights on the trailer fed by the relays, and the relays turned on by the equivalent circuit on the tow vehicle. You can put the relay on the tow vehicle, or if you also run a live feed to the trailer, you can put it on the trailer (which means it is good for more than 1 vehicle, but any tow vehicle MUST have a live feed to the trailer)
Good idea also to have the live feed relayed so it is only on with the ignition to prevent power leakage and corrosion in the circuit - and having a switch so you can disconnect the power to the hitch is also a good idea (again, so nothing is live back there to encourage corrosion when not connected to the trailer)
It would tell you if you had wiring trouble on the trailer. If it works from the pack, the trailer is A-OK - ready to go. Don't waste time on the trailer, look at the tow vehicle.
One thing that you need to remember when testing trailer lights. If the lights go "wonky" when you use the signals you have a bad ground - period. Signals on, tail lights off, and side markers glowing with the signal? Bad ground. Period. Bad TRAILER ground - not bad lamp ground, most likely - and if it is a bad lamp ground it will be on the lamp that causes the interaction.. If the signal can't get a good ground it will back feed through the tail lamp filament, which will eventually find a ground through the tail lights of the tow vehicle - making the low wattage side markers glow.
If there is no interaction between signals and other lamps you can be
99.999% sure it is NOT a ground problem. If there is interaction,
99.9999% sure it is.
I assume that you want these readings taken without the trailer plugged in.
The reading is between 0.071 and 0.084 V. It varied each I started the van and varied from side to side.
I checked it using both grounds, the ground on the flat four and the ground at the bulb socket. 13.24 volts at the tail light using both grounds. 13.3 volts at the flat four plug using both grounds.
Resistance reading from tail light ground to flat four ground with the tail light bulb out reads 0.5 ohms.
Seems to me that the problem is in the trailer, correct?
Si junction drop is considered to be .6V-.7V but diodes can easily drop over 1V at higher currents. Perhaps you're thinking about Schottky diodes? They're closer to .3V at very low currents and perhaps .7V at higher currents.
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