Bleah- yet more trailer light issues

[Bobbie Mayer]

This time when none of the lights worked I used a tester. All three lights worked at the car half of the connector if I grounded on the trailer frame. All three lights also worked when I grounded to the ground wire for the trailer wiring. None worked when I plugged the trailer connector into the car connector, which suggests to me that it is the 4-way plug that is bad at one end or the other.

All the lights worked after I drove for awhile and they presumably heated up.

So now I have a new four-way plug and I was going to wire it in and see if it fixes the problem. Does that seem reasonable?

[Thomas G.]

Most test lights have a sharp point to jab a wire. I'd plug in the 4 way connector, then jab into the wires slightly behind the point where the plugs are connected. Your test light should light up, if grounded. You also need to make sure the ground connection is working through the plug. You can do this by stabbing the ground wire on the trailer side and connecting the alligator clip to a hot (energized with 12 volts) pin on the plug.

Once you are done, seal the punctures with glue, like epoxy or liquid electrical tape.

If the plug is bad, replace it. If it checks out OK, you will need to move back to the other wiring to look for a fault. A very common problem is a poor ground to the lights themselves, especially if the frame is used as a conductor.

[Hambone]

Should....or I'm always tweaking my molded 4 prong connectors, cleaning the contacts, spreading the male ends of connectors just a tad with a small screwdriver to get better connection, die-electric grease. Never have a problem with my 7 prong but seems like whenever I use the 4 prongs on my vehicles something is always goofy (usually ground), living in MN with the salt could be part of my issue

"All the lights worked after I drove for awhile and they presumably heated up."
probably getting ground through ball

[Darwin Maring]

I think that when you drove for awhile, you had a ground connection between the ball and hitch which made it work. If so, then you have an open ground in the wiring.

[Thomas G.]

Originally Posted by Darwin Maring

I think that when you drove for awhile, you had a ground connection between the ball and hitch which made it work. If so, then you have an open ground in the wiring.

Good point. The problem may be where the ground wire from the 4 pin connector attaches to the trailer frame - a common issue.

[Bobbie Mayer]

Well, here's what happened. I rewired the new plug in (after figuring out it was the trailer side.) Then the lights worked. Then I taped the connections and hitched up and the lights went out. After much trouble-shooting (with a friend) he tried turning the screw in the light covers (where the ground is connected) and both of them lit up when the screw was wiggled.)

So it looks like multiple ground issues. I may be starting from scratch one of these days. To complicate things the former owner had switched to a seven-wire plug because that must have been on his truck so those wires are now what lead into the trailer, somewhere going back to four wires but I'm not sure where. Not easy to get to- I'll have to remove the mattress and supporting boards and get into the seat storage area. So that job will wait- today I'll wiggle the screws.

I do believe trailer owners must go straight to heaven because dealing with trailer lights is sufficient time in purgatory!

[mary and bob]

Originally Posted by Bobbie Mayer

I do believe trailer owners must go straight to heaven because dealing with trailer lights is sufficient time in purgatory!

try dealing with the lights on big trucks and trailers here in the Northeast. If it's not a ground problem, it's corrosion somewhere!! I've got many years experience with those problems, now retired and don't miss it at all.

[Chris Jones]

I have seen with trailers using the frame as a ground the tongue not passing the ground on to the rest of the trailer. A quick test for this kind of a ground issue is to take a set of jumper cables, hook one end to the tow vehicle tail pipe and the other to the trailer near where the light gets its ground. Make sure to bypass the connection between the frame and the tongue. If the lights work then you have discovered that the lights are good and that the ground is the whole problem. Then you can narrow your search by eliminating connections within the bypass of the jumper cables. This all make sence to me, but I may not be explaining it properly. Good luck with it.

[Thomas G.]

Originally Posted by Bobbie Mayer

.........
So it looks like multiple ground issues. I may be starting from scratch one of these days.........

Actually using the frame as a conductor is a terrible, but common place idea. I'd suggest to anyone rewiring a trailer to run a a separate ground wire all the way from the connector plug to each light and save yourself a lot of grief.

You generally find out the grounding has failed when you are all hooked up and ready to go - the worst possible time.

[Darwin Maring]

Thomas G is absolutely correct. That is what I did.
I also filled an old coffee can full of ground and placed it in the closet. Now I Take my ground along on all trips.

[Thomas G.]

Originally Posted by Darwin Maring

........
I also filled an old coffee can full of ground and placed it in the closet. Now I Take my ground along on all trips.

This is a terrific idea, as it seems you can never have enough ground. Also handy for helping out trailers at campsites with no ground and no working lights.

[Darwin Maring]

2 Thomas G,
It also comes in handy to fill small potholes to level the egg.

[Bobbie Mayer]

Sean was checking the ground with jumper cables and thought it was okay (trailer frame.) But the problem is the intermittence so what is okay one moment disappears completely the next.

Anyway, home safely, they worked (as far as I know) all the way home. I always keep the curtains open front and back so that in case of light failure my brake light is visible through the trailer, just in case. But before I drive south in the late fall I need to do something to avoid a repeat of last year (they worked the day I left, woke up the next morning to no lights- halfway through the trip on foggy mountain roads in Oregon.)

[Thomas G.]

Originally Posted by Bobbie Mayer

........ But before I drive south in the late fall I need to do something to avoid a repeat of last year (they worked the day I left, woke up the next morning to no lights- halfway through the trip on foggy mountain roads in Oregon.)

Seriously - consider running a separate ground wire to the lights. Not that hard and it can be redundant to the frame ground, so you don't need to undo anything.

[Hambone]

"After much trouble-shooting (with a friend) he tried turning the screw in the light covers (where the ground is connected) and both of them lit up when the screw was wiggled.)"

Bobbie, take that screw your friend wiggled to get the lights to work, make it and corresponding connection nice and shiny with some sandpaper. Do the bulb and socket also as long as your in there. I personally coat all electrical connections with die-electric grease before reassembly

[Bobbie Mayer]

Thanks, I've done that before but maybe the grease would keep things working longer. The trailer does spend half the year parked on Puget Sound so gets a lot of salt air (though not much rain this summer.)

[Jared J]

I automatically run new wires, and install led taillights with marine adhesive heatshrink on all connections as soon as I buy a trailer.

After that, they work for years. In some places of the scamp where they had scotch locks (evil things), I had to cut out over a foot of wire to find clean, I corroded wire, and that was inside the trailer.