Adapter Solution for Going from Military 12 Pin Trailer Connector to Standard 4 or 7-Way  

Question:

Expert Reply:

We do not offer any wiring adapters to convert a 12-pin female connector on a military vehicle to a standard RV-style 7-way like # 37185 or a 4-pole like # 18252. But you can install a different type of trailer socket on the truck by hardwiring one.

Based on the information I could find about your military connector the wires have letter codes on them and carry the following functions common on most trailers:

J is the right turn signal
B is left turn signal
E is tail lights
D is ground
K is 12 volt power

Usually trailers use the same wire/light for both stop and turn signals. On a 4-pole trailer connector the green wire carries right turn and stop signals and the yellow wire carries left turn and stop. If this is how your trailer lighting is set up you'll need a tail light converter on the truck to combine the stop and turn signals. You can use kit # 119250KIT. This kit includes a circuit tester to help you confirm the function carried on each wire.

The above wires will connect to the 4-pole harness as follows:

J is the right turn signal and connects to the GREEN wire.
B is left turn signal and connects to the YELLOW wire.
E is tail lights and connects to the BROWN wire.
The harness' WHITE ground wire with ring terminal grounds to the frame.

If you decide to convert this 4-pole to a 7-way format you can use part # 37185. This will plug in to the 4-pole and provides 3 additional wire leads with butt connectors for the extra circuits. Typically these extra circuits are for trailer brake signals (blue wire), reverse light signal (purple wire) and for 12V auxiliary power for the trailer (black wire).

If you do need trailer brake signals then instead you can use our kit # ETBC7 which has a 37185 plus other items to give you a fully-functioning 7-way, such as wiring, circuit breakers and connectors. I have linked an install video for the ETBC7 to show you the process in a 1994 C/K series pickup.

expert reply by: Jameson C

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