Weird Science (7 way plug, help!)

[Blakradish]

I decided to be a hot shot and try and replace my 7 way trailer plug and wire (they were cracked and frayed respectively).
I purchased both correct parts and when I unwrapped the mess of electrical tape holding the old cord together I found 2 sets of 2 extra wires spliced (poorly) into the old cord. My question is, should I just re-splice them into the new cord and forget about it, or should I find what they go to and do it right.
I am NOT mechanically inclined nor can I afford to hire someone who is.
I'm pretty sure they are 2 ground and 2 hot wires and they are black and white.

Thanks,
Blake
'63 Avion H-24

[GeocamperAS]

If everything worked well, I would install the new one just as I found the old one. Tracing wires could be a long and involved job.

[remcolent]

I'll gues frayed means burned.
If there are extra wires there has been a problem before.
Tracing wires and use a volt and ohm meter is not rocket ceience.
Do you have a wire diagram of your trailor ?
A bad conection on the wire can genarate a lot of heat and when your unlukky a lot of flames.
Remco

[overlander64]

Greetings Blake!

This is a guess on my part, but I would be highly suspicious that the extra wires spliced into the bundle may be for your break-away-switch and possibly for an electric tongue jack. It is my understanding that the break-away-switch didn't become standard equipment until later in the 1960s, and often electric tongue jacks were added after-market to make the chore of hitching easier.

Good luck with your project! I have attempted the project twice - - once with near perfect results and the second time it was an exasperating experience that resulted in a trip to a qualified RV technician.

Kevin

[jdalrymple]

Any chance the two "extra" identical pairs are the headed to the brakes? If they are tied together, that may be what they are.

I would set a battery near the front of the trailer. Ground the negative post to the trailer frame, and one at a time touch the wires to the positive post and see what lights up. A safety net would be to hook a fuse holder, available at wal-mart, to the positive post and touch the trailer wires to the fused wire. If the fuse blows, that wire does not belong to a positive supply.

This process would identify your wiring harness. The brake magnets will hum when you apply power. Keep the time you have each wire attached to the power to a few seconds until you know what it goes to.

Not everyone will agree, but with just a little common sense this works fine.

Good Luck,

[Blakradish]

Thanks all,
I've got an electric tongue jack so I think thats one, The others wires reach back to about mid trailer and are on the [U]outside[U] of the belly pan (like somebody didn't feel like going in so they just strung new wires on the outside). I'll try and visually trace these and if that doesn't work I'll try the battery thing.

Thanks again,
Blake
'63 Avion H-24

[Blakradish]

OK,
I found where the wires definitely go. One set is to the brakes and the other set is to the electric jack. Thanks for the insight guys I really appreciate it.
I have a concern though (I have lots, but lets talk about one), The hot wire for the jack is spliced in such a way that one wire runs from the jack directly to the battery (so that it doesn't have to be plugged in to the truck) and the other runs from the trailer plug to the jack (in case the house battery is low?) they are spliced together, and so isn't that 2 12 volt sources opposing each other? I have used the jack in past whilst plugged into the truck and I don't think there's been a problem. What am I missing (besides common sense)?

Thanks
Blake
'63 Avion H-24

[remcolent]

There is no problem that 2 12 volt sources opposing each other.
As long as there no conection made between a hot wire and a ground wire.
Your car is charging the trailor battery while driving.
Make sure that the wires are spliced good and that there is a good conection.
The brakes takes a lot of amps.
If there is only a little bit or recistance in the splice your brakes may not work properly.

Remco

[Blakradish]

Thanks Remco,
So dumb of me, I didn't even think about the charging scenario.

Blake
'63 Avion H-24

[Blakradish]

Hey All,
Another Question. I'm into this screwed up cord which is really confusing me. I've spliced all of the wires except for the BLACK wires (of which I have 3 trailer side) and the WHITE wires (also 3) all of these have to be spliced to the 1 BLACK and 1 WHITE on my Tow Vehicle cord.

Question 1- Can I run a 2 of the trailer side White ground wires to the frame instead of to the cord (they are for the jack and brakes).

Question 2- Is the 1 Black wire enough to power everything? granted I won't be using the Jack and Brakes at the same time but... and what is the black wire for INSIDE the cord anyway?
Is that my 12v charging wire?
Also the yellow wire on both sides were not in use nor is the center post on the TV plug
I'm confused.

Thanks,
Blake
'62 Avion H-24

[remcolent]

Hi Blake

Do you have a wire diagram of your trailor.
You can send it to me by email it makes things a bet easyer to explane.

Q1 The ground of the brakes MUST be on the cord and have a good conection.
Also the ground for your outside lights should be on the cable.
The rst can be on the frame as they use the batery of your trailor.

Q2 Yes as long asa it is thick enough 4 mm sq is ok

Remco

[overlander64]

Greetings Blake!

Originally Posted by Blakradish

Hey All,

Question 2- Is the 1 Black wire enough to power everything? granted I won't be using the Jack and Brakes at the same time but... and what is the black wire for INSIDE the cord anyway?
Is that my 12v charging wire?
Also the yellow wire on both sides were not in use nor is the center post on the TV plug
I'm confused.

Thanks,
Blake
'62 Avion H-24

The one thing that I may be able to help you with is the center post of the typical 7-pin connector. When wired to the current standard, the center pin usually handles backup lights. My experience has been that the trailer centers who have wired in my tow vehicle connectors refuse to connect the backup light circuit unless I put it in writing and remind the sevice manager that I won't be paying his bill until this part of the job is completed.

Generally, the black wire inside of the Bargman umbilical cord is a the 12-volt charge wire, but this varied over the years according to the manufacturer of the travel trailer . . . . the modern standard would be 12-volt charge lines, but the modern standard goes out the window when working with Vintage travel trailers of any brand.

Good luck with your project!

Kevin

[Silver Goose]

If the world was perfect, the color coding of the wires would be identical on all TT and all TV. In fact most are, but to say with absolute certainty that the white wire is ground on your trailer without testing isn't prudent. This diagram should be helpful. The pin numbers should match the functions on your TV.

The bottom line is that you will find 7 wires:

1. Ground
2. Electric brakes
3. Tail/marker lamps
4. +12V charge line (may be tied to hot side of breakaway switch
and power tongue jack as well as TT battery + post)
5. Left turn/brake lamp
6. Right turn/brake lamp
7. Backup lamp

A 12V test lamp that you can find at any auto parts store is a simple way to confirm the function of each line on the TV socket. It is an inexpensive tool you may find useful later on to help isolate other possible 12V problems. As mentioned earlier, using a fused +12V probe is a straight forward way to apply voltage to each line on the TT end. I would use a 10A fuse. It should only blow when you find ground, otherwise you should see which lamps light up. Be prepared for some sparks whenever you touch the probe to a line; turn the gas off just to be safe. Do not leave the power applied to the electric brakes for a prolonged period to prevent brake coil damage. The combined current draw from all coil magnets may blow the fuse, particularly if one of the coils has worn down to the wires.

Hope this helps.

[Blakradish]

Thanks for all of the Information everyone it's helped A LOT.

I have finally figured out (and tested) all of the wires in my cord, and low and behold they are all correct and working! Stupidly I thought that the brakes (which were wired OUTSIDE the cord) were on the 12v wire when they were on the blue brake wire (say that 3 times fast).
I also disconnected the cord from the jack to the TV. I live full time in her and am not traveling much at the moment. I can replace it if needed, and I also have a hand crank.

ONE MORE THING.
I cannot tell if the black 12v wire from the cord in the trailer goes to the battery. If I place a grounded meter on the wire I get nothing. Shouldn't it feed back a charge?
(Remember that the PV spliced off of the 12v to the Jack which was also connected to the battery, could that wire also have been be the charge wire?)
When I tested the batteries yesterday with the Jack/TV splice in and the cord plugged into the truck the meter read 13.87v. Today when I took the splice out and retested the meter read 12.87. Crap, I just realized that I probably cut the hot charge line to the battery.

Sorry, but writing through this helps. This forums awesome.
Are there any good looking Female Electrical Engineers who want to move to Washington State? I'm single.

Arghhh!
Blake
'63 Avion H-24