damn trailer lights

Okay, I hate working on these things!
1st/2nd pic is the connection at the truck, the lone male plug on the right broke off. This connection has 5 colored wires. I have a new plug setup, with only 4 wires, pic 3. The new setup is just like the trailer wires. 5 wires into 4. Which two wires coming from the truck go into the one plug?

I dont know nothing really about electronics for the most part.  But I've had to figure these things out before, and I'll give you my best *guess*.

Looking at the wires, the odd man out seems to be Red.  Since the 4-Wire harness has White, Black, Yellow, and Green, I'm going to make some assumptions.

White and black are most likely power.  Green likely ground.  Yellow, going to really guess here, ON/OFF.

Red looks to me like it would be the same as either black or white (which ever is positive).  Since there are two lights, might make sense that there are two different power feeds, one for each light.

So, I think you could do a VOM reading on the black and white and red wires to figure out where the voltage is coming from.  Bridge the two Positives, and hopefully your good!  Or, just connect it without the red wire, and see if only one light lights up!

Maybe i'm totally wrong though Juan

Oh, and I had too much coffee today 

Okay Al, you got me going. I'm getting the voltmeter out and we'll see where that gets me.
It never fails, I wanted to take the forgotten boat out for a spin today, and it's always something. I love my yak all the more.

I dont know nothing really about electronics for the most part.  But I've had to figure these things out before, and I'll give you my best *guess*.

Looking at the wires, the odd man out seems to be Red.  Since the 4-Wire harness has White, Black, Yellow, and Green, I'm going to make some assumptions.

White and black are most likely power.  Green likely ground.  Yellow, going to really guess here, ON/OFF.

Red looks to me like it would be the same as either black or white (which ever is positive).  Since there are two lights, might make sense that there are two different power feeds, one for each light.

So, I think you could do a VOM reading on the black and white and red wires to figure out where the voltage is coming from.  Bridge the two Positives, and hopefully your good!  Or, just connect it without the red wire, and see if only one light lights up!

Maybe i'm totally wrong though Juan

brakes?
running lights??

I'll take a look at mine later tonight.

This might help?

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

This might help?

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

Well, from the looks of that I'm totally wrong! 

I went the simple route. I ran the red/green coming from the truck, together into the solo green on the new harness. Initial success, until I step on the brakes, then the right blinker goes on.
I'm going to go and check out Alfredo's suggestion now.

White is ground, brown is running lights, green is turn rt, yellow is turn lft. The single one that broke off is your ground.
   The only thing I can suggest on the red is to get a test light, pierce the red wire with the pointed end and ground the other side. Try each circuit(running lights, lft turn, rt turn, and brake) and see what turns on the test light. I doubt that it is power since it connects with one of the other circuits, but if the test light comes on just by connecting the ground and piercing, it is power. I'll research further if need be. I wire race cars and deal with high end cars sometimes. Trailers I do wire once in a while, but I have not seen the extra red wire on a flat plug set up. Only on 6 or 7 pin connectors.

Hey, I have a thought. Does the cover for the plug have an LED light in it? If so, that is what the red is for. Just don't use it on the new one if that is he case.

Together, going by the site Alfredo provided, and what the guy at the auto supply store discovered, I was able to fix the damn trailer lights. Turns out what I wanted to was never going to work out (5 wire into 4). I ended up buying a whole new harness for the truck, $50. What was great is that there is no cutting of wires, no soldering, no electrical taping. You take off the tailight covers to access where the existing harness plugs into the light, and plug the trailer light harness right in.
Before this it was such a mystery!

Glad to hear you got it worked out. I have a new plug-in harness kit to install on my Escape. Sounds similar.

Al