Plug and play trailer wiring - 7RV conversion

[ComatoseLlama]

Hello,

Quick question, I have the factory trailer wiring plug marked C321A-9E, which feeds to two grey plugs, to a 6 round plug, I need 7 RV plugs for my trailers.

Googling that part number brings up a few options for plug and play solutions. But none of the websites say they’re compatible with my truck. Are any of these the correct plug?


https://www.amazon.com/dp/B000NUEO8G/ref=cm_sw_r_cp_api_i_L0iQEbWJ36ADQ

https://www.amazon.com/dp/B000NUD7MA/ref=cm_sw_r_cp_api_i_Y3iQEb2WK9E2P

pics of trailer wiring, along with 2 wires that seem to go nowhere :

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(the go nowhere wires are aftermarket i figured out. Something to do with the camper that used to live in the bed

 

[chillman88]

Any of the plug and play options are NLA (no longer available). I did the same song and dance with my truck. In the end, I bought a repair harness that would work for a... 2008? And wired it in so I'd have a standard plug to reference and replaceable parts.

If you would like me to do a little digging I'll see if I can find the link to the one I ordered.

EDIT: https://www.amazon.com/dp/B000BGHV6Y/ref=cm_sw_r_cp_awdb_t1_nGlQEb7ABJGZM

That's what I ended up going with for mine. Will require wiring it in though.

 

[79jasper]

All you really need is the socket. For most, the 7th wire is just reverse lights.


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[ComatoseLlama]

Guess I’ll wire in an aftermarket one!

Having trouble finding a pinout of the plugs,

one plug has

white/red
Green/red
Black/purple
Orange blue

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I assume these are turn signal and brake lights, etc

other plug is thicker wire, with

white
Yellow
Red/green
Blue/black

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Isn’t that one too many wires?

 

[chillman88]

Yes it is. I don't remember if I ever figured it out honestly. I checked them all with a multimeter for function. I think one of them runs into the cab in the bundle for the brake controller. One of the green and red ones. Going by memory so I could very well be wrong. I left it unhooked on mine.

 

[79jasper]

Probably be better off with a wiring diagram than the plug pinout.
You can't look at it going into your current trailer plug?

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[79jasper]

CIRCUIT COLOR CODE CHART
CIRCUIT FUNCTION - OLD COLOR* - SAE COLOR*
Trailer LH Turn/Stop - LG/O - Y
Trailer RH Turn/Stop - O/LB - DG
Trailer Brake Lamp From Controller - R/LG - R/LG
Trailer Electric Brakes Solenoid - BL/BR - DB
Trailer Back Up - BK/PK - R/Y
Trailer Ground - W - W
Trailer Running/Tail - W/R - BR/W
Trailer Power (Battery Charge) - Y - O
Trailer Brake Control Feed - R - R


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[ComatoseLlama]

Thanks Jasper!
FIRST PLUG::

Trailer LH Turn/Stop --- Light Green/Orange

Trailer RH Turn/Stop --- Orange/Light Blue

Trailer Running/Tail --- White/Red

Trailer Back Up --- Black/Pink



--------------

SECOND PLUG::


Trailer Ground --- White

Trailer Power (Battery Charge) --- Yellow

Trailer Electric Brakes Solenoid --- Blue/Brown

Trailer Brake Lamp From Controller --- Red/Light Green

----------------

Need to find ::


Trailer Brake Control Feed --- Red

My truck has the brake controller plug by the e brake, should I find where that pops out or just run a red wire back from the controller?

 

[79jasper]

I found that on a bronco forum. I searched 1989 f250 factory trailer wiring diagram.
One of those is fir the brake feed, I would run a newer larger wire. Ford (and any manufacturer of that era) was known for undersized wiring.

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