Trailer hook up to RV help

[speedydd]

I have a class A 1999 national Seaview Rv.
Im trying to hook up my trailer to it, to haul my four wheeler. RV has a 6 pin round plug. My trailer has 4 flat plug. I have tried several adapters and nothing still works as it should. I'm at a loss on what to do to make it work properly.
When I push the brake, all lights go out and when I use turn signals, they just stay solid. So we unhooked from 6 pin plug and tried to wire straight to the 4 flat wires and breaks worked ok but turn signals then flashed like emergency lights were on, each side to signal, also tried a tail light converter for independent signal lights and trailer lights won't even come on at all ugh Soooooo I'm exhausted trying to figure it out and need help, if anyone has experienced this and is there any other special way or device I need to make it work. The 6 pin has a black power wire not sure what to do with it to.
Thank you in advance

[ScoobyDoo]

Think I answered this someplace

[speedydd]

Yes u did thank you

[tawakoni]

Troubleshooting electrical problems is one of the toughest things, and there is absolutely no way to do it w/o "hands on". I can give you one bit of advice. Try hooking up ONE THING at a time. Sometimes that will give you a clue as to what the real problem is.

If the "power wire" you speak of is the 12v then that is simply a trailer connection that is used for accessories on the trailer. (Like inside lights on a horse trailer that have their own switch. we use them loading horses at night)

'dave

[speedydd]

Thank you so much that was great advice I'll be working on this the next sunny day

[SmokeyWren]

Originally Posted by speedydd

Im trying to hook up my trailer to it, to haul my four wheeler. RV has a 6 pin round plug. My trailer has 4 flat plug.

First let's gain some knowledge about what those 6 pins and 4 pins are supposed to do.

Click on the following link to see the wiring diagram for a 6-pin trailer plug coming out of the back end of your RV.

https://www.bing.com/images/search?v...x=5&ajaxhist=0

The 6 wires are for
1] tail lights, running lights
2] ground,
3] left turn/stop lights/flashers,
4] RV battery charge,
5] right turn/stop lights/flashers
6]trailer brakes.

The 4-pin flat wire does not have the wire for RV battery charge or trailer brakes. So your trailer must not have a battery in the trailer, and it doesn't have trailer brakes.

So you need a simple adapter. Here's the internet search terms I used in bing.com:

trailer plug adapter 6 pin to 4 pin

And here's one hit:

https://www.delcity.net/store/6-Way-...20group%20%231

[Beowolf]

Isn't there an RV style and a utility style? Would a standard 7 pin to 4 pin work for both wiring schemes on the 7 pin?

[SmokeyWren]

Originally Posted by Beowolf

Isn't there an RV style and a utility style?

Hers is an old 6-pin round plug on the RV. Not a modern 7-pin RV plug. The 6-pin plug was used on large livestock and horse trailers back then, and apparently on some motorhomes. But now they are rare, and even the cowboys use 7-pin wiring.

Yes, the 6-pin plug has two different wiring diagrams as seen in the link to the wiring diagram for a 6-pin plug I posted. But the difference is only which pins are used for trailer battery charge and trailer brakes. Because the 4-pin flat "U-Haul" plug on her trailer doesn't have pins for battery charge or trailer brakes, the adapter should work regardless of which 6-pin plug is on her RV.

Would a standard 7 pin to 4 pin work for both wiring schemes on the 7 pin?

No. A 7-pin adapter will not plug into her 6-pin plug.

A standard 6-pin to 4-pin adapter should work if her 6-pin plug was OEM equipment on her motorhome. But I suspect it was an aftermarket add-on by a previous owner, and not wired to the standard 6-pin specs.

If a standard 6-pin to 4-pin adapter won't work, then she needs to have a trailer wiring expert re-wire the 6-pin plug on her motorhome the to be sure the 4 wires for
1] tail lights, running lights
2] ground,
3] left turn/stop lights/flashers,
5] right turn/stop lights/flashers
connect to the correct pins on the 6-pin plug on her motorhome.

The two wires for
4] trailer battery charge, and
6] trailer brakes (brakes, not stop lights)
should not be connected to the 6-pin plug because her trailer doesn't have a battery or brakes, and I suspect it's those two wires that are giving her fits.

[speedydd]

Originally Posted by SmokeyWren

Hers is an old 6-pin round plug on the RV. Not a modern 7-pin RV plug. The 6-pin plug was used on large livestock and horse trailers back then, and apparently on some motorhomes. But now they are rare, and even the cowboys use 7-pin wiring.

Yes, the 6-pin plug has two different wiring diagrams as seen in the link to the wiring diagram for a 6-pin plug I posted. But the difference is only which pins are used for trailer battery charge and trailer brakes. Because the 4-pin flat "U-Haul" plug on her trailer doesn't have pins for battery charge or trailer brakes, the adapter should work regardless of which 6-pin plug is on her RV.



No. A 7-pin adapter will not plug into her 6-pin plug.

A standard 6-pin to 4-pin adapter should work if her 6-pin plug was OEM equipment on her motorhome. But I suspect it was an aftermarket add-on by a previous owner, and not wired to the standard 6-pin specs.

If a standard 6-pin to 4-pin adapter won't work, then she needs to have a trailer wiring expert re-wire the 6-pin plug on her motorhome the to be sure the 4 wires for
1] tail lights, running lights
2] ground,
3] left turn/stop lights/flashers,
5] right turn/stop lights/flashers
connect to the correct pins on the 6-pin plug on her motorhome.

The two wires for
4] trailer battery charge, and
6] trailer brakes (brakes, not stop lights)
should not be connected to the 6-pin plug because her trailer doesn't have a battery or brakes, and I suspect it's those two wires that are giving her fits.

Thank you so much for this info im gonna pass this to my helper and hopefully get it working ill post update when im finished. ☺[emoji106]

[YC1]

Your symptoms scream of a bad ground.

Use a test light and NOT a voltmeter. Leave the trailer disconnected.

Make a clean ground on the frame. Grind or sandpaper if needed.

Clip test light to that ground. Now with note pad in hand test each pin of the rv.

With that sorted you can move on to the trailer. Scratch a clean ground onto that frame. Connect a wire between the two units. A car jumper cable is excellent for this test.

Now use a single scrap wire to jump from a pin on the RV to the pins on the trailer. You can use the test light as that jumper but things will be dimmer but you won't blow a fuse either.

You probably have more than one problem on the trailer. Crappy grounds or corroded sockets will make a qualified tech go mad.

If you have a battery handy you can skip the RV at first and go about making the trailer lights function. You do need a jumper wire with a fuse inline for safety. You can buy these at any automotive store. Grab a bag of fuses too. 10 amps for testing is fine.

In any case, you must have a clean ground or you may as well not try.

[ScoobyDoo]

Originally Posted by YC1

Your symptoms scream of a bad ground.

Yes, if all lights act up the ground is likely the problem because all light use the same ground.

Use a test light and NOT a voltmeter. Leave the trailer disconnected.

With a volt meter I can normally tell if a circuit is marginal, a test light is less accurate, but will get the lights working. I don't want more problems later, so before I call myself done it all will be checked with the meter. YMMV

Make a clean ground on the frame. Grind or sandpaper if needed.

Clip test light to that ground. Now with note pad in hand test each pin of the rv.

With that sorted you can move on to the trailer.

After the good start;
"Your symptoms scream of a bad ground."

You want to move to the trailer without checking what you know to be the most likely problem?

OP, if you have found you have good power on the tail pin you can leave one end of testlight on that pin, and put the other on the ground pin to check that it is in fact grounded (Bet it fails this test)

Scratch a clean ground onto that frame. Connect a wire between the two units. A car jumper cable is excellent for this test.

This statement is enough to get you benched as trailer lighting tech...

Once you are sure everything on the TV is working as it should, plug in the light cord, with nothing else making contact TV/trailer and check the lights. If you still have issues, do the checks on output of adapter. If good, then check at the end of cord, find the bad ground
Over decades I have worked on truck and trailer lighting. And sometimes, if a trailer had been setting out in the weather for years I would find more than one problem. Most times that fixing one thing didn't solve all the problem it is because somebody has messed with it...

[SmokeyWren]

Originally Posted by speedydd

... hopefully get it working ill post update when im finished. ☺[emoji106]

Unasked for advice:

A plain ordinary 12-volt test light will work fine to be sure you have power on the correct pins on the 4-pin plug on the adapter. My test light is a tiny LED light with a two-wire pigtail that plugs into the female pin recepticles on the 6-pin plug on the motorhome. It looks like the one at the top right of the page of the Wikipedia website:
https://en.wikipedia.org/wiki/Test_light

You need to test:

1] tail lights, running lights
2] ground,
3] left turn/stop lights/flashers
5] right turn/stop lights/flashers

You need a helper to test the plug, to step on the brake pedal when required, turn on the flashers when required, and turn the lights on and off when required.

1] To test the tail lights, the lights must be on so the tail lights on the motorhome are lit. Then the pin for the tail lights should be "hot" when you have the black wire of the test light in the correct pin and touch the ground wire of the test light to the ground pin of the plug.

3] To test the pin for the left turn signal light, the motorhome lights should be off, and the left turn signal on so the left turn signal on the motorhome is flashing. If the pin is hot when the turn signal is flashing, then the next step is to turn off the turn signal and step on the brake pedal. If the pin is hot when the brake pedal is mashed, then get off the brake pedal and turn on the flashers.

5] To test the pin for the right turn signal light, repeat the test for the left turn signal except on the pin for the right turn signal.

If those three pins are hot when they should be, then the ground pin is working as designed. When you plug in the adapter to the 6-pin plug, the 4-pin plug on the adapter should work when you plug the trailer's 4-pin plug into the adapter.

[YC1]

Benched as a trailer lighting tech????????????

I'm a telecommunications technician with over 40 years in the businees and over 50 years in electronics.

I own an electronics repair center where we deal with hundreds of vehicles every year. "Scratching a ground" is often done with a dremel before using a screw and star washer to install a good ground.

After training too many technicians to count over the last 40 years I doubt I will get kicked off the work bench. As a matter of fact I have been the go to guy for most of those years.

IMHO

[YC1]

The reason for recommending a test light for a novice is a digital meter can read full voltage but not have enough voltage to light a bulb.

For example, You can put the negative lead of your digital meter on the battery post and then with your positive lead between your fingers on one hand then touch the positive post of the battery you can literally make the meter read the full battery voltage.
There is not enough current to light a bulb.

So it is easy to get fooled with a meter. My 12 volt test lights live right next to one of my meters. If it is light bulb issues the test light is my go to first test.