Wiring to Tow Vehicle

Willky · 07-13-2018, 04:38 PM

Hi. I have a 2009 139x and the recent owner did not use the trailer brakes and converted the plug to the standard 4 pin connector. That works fine as far as the lights but I want to go back to the 7 pin circular connector and use the brakes. On the 139x I have a blue, black and yellow wire that has been cut off. Which wire is what? I am all set with the locations on the connector but not what they cut. thanks.

**LJAZ** · 07-14-2018, 10:05 AM

Blue is for the trailer brakes, Black is 12V power and Yellow is usually for the left turn signal. There are some variations though, especially if the PO did some rewiring.

Chirpz · 07-15-2018, 05:06 PM

Check out this link.... nice diagrams.

https://www.ajtnt.com/7-way-rv-plug-diagram/

There are many others.... just google it.

Willky · 07-20-2018, 03:07 PM

Thanks guys. Unfortunately they did rewire it wrong. What I have now from the 4 prong connector is: 4prong green is now to brown on the FF harness, 4 prong yellow is hooked to red on the FF, 4 prong black is hooked to green on the FF and 4 prong white is hooked to white on the FF. That leaves me with blue, black and yellow on the FunFinder. And yes the tail lights, brakes lights and turn signals do work properly when I hook it up so unfortunately they must have done some serious rewiring inside the trailer or at the lights also.

**LJAZ** · 07-21-2018, 09:33 AM

Yikes. They should have just connected the 4 wire plug wires to the corresponding colors on the 7 wire harness. What they did seems like a lot more work. Now you're going to have to trace everything back to where they made the cuts in the original trailer harness. Fortunately, most of it should be accessible from under the trailer.

snlsmith · 07-21-2018, 03:54 PM

Quote:

Originally Posted by LJAZ

Yikes. They should have just connected the 4 wire plug wires to the corresponding colors on the 7 wire harness.

Even easier and better, just use a 7-pin to 4-pin adapter plug.

**LJAZ** · 07-22-2018, 10:01 AM

Quote:

Originally Posted by snlsmith

Even easier and better, just use a 7-pin to 4-pin adapter plug.

Yeah, makes you wonder if the PO somehow damaged the trailer wiring harness and came up with this kluge with whatever materials were on hand.

Willky · 07-25-2018, 06:41 AM

Thanks. The 7 to 4 pin adapter works fine but the trouble is legally it is heavy enough so that I need the proper wires for the electric brakes and charging to the camper. Plus I want to do it for safety.