Originally Posted by eddieleephd

be sure that you have a good ground between vehicle and trailer!
This can easily create such an issue.
First check that you get a complete circuit at the plug for the trailer, then go to the trailer first checking positive grounding!
The ground may be the most important part of the equation~

Originally Posted by Ron Helmuth

Dragged home a $200 Subie the other day for my 16 year old and could not rent a tow dolly at UHAUL because...

my 4pin tow light connector is not functioning for turn signals-headlights seem to work fine.

I search some threads to convince me to rip apart the drivers side rear cargo area panels to get to the taillight converter black box stuffed in the rear corner. Dang that is a bunch of work to open up that massive a$$ panel, though not particularly difficult.

I convince myself that the 4 pin wiring is bad (it was crimped with wiring poking out of the insulation) and buy a $7 kit to rewire it.

Still not functioning for turn signals. Yes I double checked my wiring and with the color coding I could not find a way to screw that up.

My buddies over at IRBIS OFF ROAD helped me out and let me test my black box and no improvement using their black box

I examine the black box closely and notice that the 6 pin input is really only using 4 wires anyways (1st question-why the heck is this box even needed when a simple connector could do the job?)

so from left to right-clip side up-top row-the 6 pin wiring is green, then green yellow in the middle and right side is empty.

Bottom row from left to right-clip side still up-the wiring is green white and green in the middle and far right is again empty.

So while a 6 pin connector-it only carries 4 actual wires.

That is correct-2 wires are plain green. I call the top left one the headlights and the bottom middle one the left turn signal.

Just for grins I stuck the wiring of the 4 pin cable running to my hitch into the 6 pin ports and voila! it seems to have solved my issues. I am measuring voltage at the 4 pin at the hitch for each function.

2nd question-any reason I can't just bypass this stupid (err smarter than me) black box and wire up the 4 pin leads straight to the wires leading to the 6 pin connector?

3rd question-should I be concerned that the voltage measured is less than 12 volts for any function? All measurements taken with engine off.

I get 11.47 volts at the headlight pin, variable results for each turn signal-digital multimeter used and it just keeps bouncing all over the place.

Anyone with recent experience with this? I welcome your thoughts before I pull a major FUBAR and start cutting pigtails.

I need to put my back end back together...

EDIT: The solution turned out to be-eliminate the Toyota black box and splice in a Hopkins "4 wire flat" to replace the existing 4 pin connector. Hopkins part number #48055 includes 4 LED lights to show what functions are working and which are not. These LED lights are visible at the trailer connector outside the vehicle, making it much easier to keep track of what functions are working properly and which do not. Careful documentation of which wire is which leading into the 6 pin connector-which then plugs into the black box- will assist in wiring up the Hopkins product.

FURTHER EDIT 053009- Ended up also buying a Hopkins #43145 taillight converter box with plug and play wiring harness ($34.75 Amazon) . This product presumes that your 4Runner has never had a 4 pin connector sticking out the back end near your hitch. It plugs into the left and right turn signal harnesses to feed signal to the 4 pin trailer connection. Because I already had an existing Toyota taillight converter box I simply spliced in the 5 -(not 4!) input wires and connected the 4 wire output to the Hopkins LED indicator 4 pin mentioned in edit above. The 5 wires converting to 4 is the whole purpose of the taillight converter. Those input wires are 1/ Left Turn 2/Right Turn 3/BrakeLight 4/ Parking Light/Headlight 5/ Ground.