4 prong trailer wire replacement

[7lazy77]

I am replacing the (vehicle end) trailer plug-in since it is old & pretty beat up. Sorry for my "lack" of correct terminology, I am far from being an electrician. When I tore off the electrical tape, this is what I found:
The green (trailer) wire is connected to the green (vehicle) wire & the yellow (trailer) wire is connected to the yellow (vehicle) wire. But here is where it gets confusing.....Both the brown & black (trailer) wires are connected to the brown (vehicle) wire & the white (vehicle) was not spliced to anything! Why would the two be spliced into the one & why wouldn't the white be connected to anything???I am trying to figure out how to splice in the new plug-in, but I am lost. Any help is greatly appreciated.

 

[Silvertip]

Re: 4 prong trailer wire replacement

Here again, a voltmeter or test light is your friend to identify what wire is what. However, the brown wire should not have anything spliced to it. It is the constant +12 volt feed to the tail and marker lights. White is ground. The white wire in the new truck end of the harness conencts to the chassis (clean connection) but it could be spliced to the current white wire but you have no idea whether that is good or not. Yellow and green are the turn signal connections.

 

[7lazy77]

Re: 4 prong trailer wire replacement

Better pic.


Silvertip: There is no current white wire coming from the trailer end, there is a black though. Does the black (trailer) wire hook up the white (vehicle wire)?

 

[roscoe]

Re: 4 prong trailer wire replacement

Better pic.
View attachment 117252

Silvertip: There is no current white wire coming from the trailer end, there is a black though. Does the black (trailer) wire hook up the white (vehicle wire)?

no, as you stated the black wire is spliced into the brown wire.

The white wire should be bolted down to a bare metal area on the trailer frame.

There should not be a black wire on the trailer.

This would be easier if you would just rewire the entire trailer. Sounds like someone did a hack job on the trailer wiring.

The lights are usually grounded to the frame, then the frame is wired to the white wire at the front harness.

More and more the more prominent trailer manufacturers are running a ground wire from the light back into the harness, as this eliminates the most common problem for faulty lights.

I would buy a new set of lights that comes with the wiring harness and install - all new.

Then pack the old lights away to use as spares when you need them.

 

[7lazy77]

Re: 4 prong trailer wire replacement

Sure looks like the original wiring on the trailer, the "hack job" appears to be in the splice to the vehicle plug-in wiring.

 

[roscoe]

Re: 4 prong trailer wire replacement

.Both the brown & black (trailer) wires are connected to the brown (vehicle) wire



That is not original.

 

[sje0123]

Re: 4 prong trailer wire replacement

This should help a bit to sort everything out...

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

 

[dpoff]

Re: 4 prong trailer wire replacement

I`m thinking someone replaced a brown wire from one side of the trailer with a black one because black wire is all they had. Trace the black wire back and see where it goes. If it runs to your running lights your OK.

 

[Rocky_Road]

Re: 4 prong trailer wire replacement

Could be that someone added side markers, and used what wire they had on hand (black). In that case it would be spliced with the standard brown (running lights) wire.

Happy boating!

 

[bassman284]

Re: 4 prong trailer wire replacement

So how was it all working without a ground?

 

[roscoe]

Re: 4 prong trailer wire replacement

We don't know that they were.

But if they were, very unreliably.

But the lights are grounded to the trailer frame, and the frame grounds to the tow vehicle thru the hitch.

 

[7lazy77]

Re: 4 prong trailer wire replacement

All lights were working without the ground wire.

 

[mxcobra]

Re: 4 prong trailer wire replacement

untill the cops are behind you

 

[jetterbug]

Re: 4 prong trailer wire replacement

untill the cops are behind you

I hear you there. That's how my luck goes. Usually after being out on the boat all day with a full cooler