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Trailer Wiring for 4 wire and 6 pole receiver

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After searching the forums is became apparent that there is a lack of information on wiring trailer harnesses to the MJ. Although it would be nice to get one of those 'plug and play' type kits that are available for the newer vehicles, they are in very short supply for the 86-92 trucks we drive (at least down here).


Jeepcomj had a great idea in one of his posts, go to the junkyard and get the under body to stop/turn/parking light harness connector (both sides), leaving enough loose wires to create your own 'plug and play' set, but that still does not address our hook-up problem...so:


The rear stop/turn/parking harness has 5 actual wires in it, and although there are numerous factory splices to duplicate wires to each of the plugs, the wire codes are as follows:


Brown: Right turn and brake light

Black: Ground

Blue: Tail (parking) lights

Brown with white tracer: Backup light

Grey with black tracer: Left turn and brake light


Another way to explain it: Assuming you are standing at the the back of the truck, the LEFT side being the drivers side, and the RIGHT side being the passenger side, the main body ground will be behind the left tail light, and the plugs on the left side will have the gray w/ blk tracer wire. The right side will have the brown wire.


To hook up a six pole receiver you have six wires:


White: Ground (Don't ask why...)

Brown: Tail (parking)

Yellow: Left Turn

Green: Right turn

Blue: Electric trailer brake

Red: Auxillary



Harness TO Receiver:


Brown TO Green

Blue TO Brown

Black TO White

Brown w/white TO Red (my choice - my trailer has reverse lights)

Grey w/black TO Yellow


For a 4 wire flat connection it would be:


Harness TO Flat 4:


Brown TO Green (sometimes with yellow tracer)

Blue TO Brown

Black TO White

Grey w/ black TO Yellow



Hope this helps! :cheers:

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Thanks for the great write-up!

I used this to take it a bit further and create a plug and play trailer harness using both ends of the connector from a spare rear wiring harness I acquired.

It just goes between the rear harness of the mj and the tail light harness :thumbsup:

Worth the effort in my book as spares my tail light harness from being hacked up; and luckily for me the spare harness had already been hacked up and had the flat 4 connector with it.


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As a Retired commercial truck driver, I love 7 wire. Its expensive but it keeps all the wires together in one package and if you are out on the road and need a replacement. Any truck stop has it on hand. 

My comanche wire all go into a junction box. With ring connection. Water, mud, rodents resistant. Then it goes to a 7 wire RV plug. Then if needed I have an adapter to 6/4 plug. 

My trailer has a junction box too. Easy to replace the lead to the trailer if ground down from dragging.  Also its easier to chase shorts. Picture coming soon. 

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