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Discussion Starter #1 (Edited)
OK guys. Been racking my brain here on the simple idea of converting the 4 PIN to a 7 PIN connector. Read the forums which pointed me to the adapter so I could plug in the factory 4 PIN and that was awesome. Ran 10 AWG wire from the front to the rear for the 12VDC. Ran 10AWG to the inside for the trailer brake controller. Grounded to the chassis(yes i scraped to metal and connected). My question is where in the heck does the reverse light wire go? I've seen people tap into the reverse wire in the rear but I wonder if this is right or wrong. Also the guide says 10 gauge was OK for 12 volts 30 amps up to like 20 ft or so but this wire is really thin. Is that the right gauge for this application?

I still have the fun of wiring up the brake controller. Not hard but just in a time crunch as we pick up the travel trailer on Thursday! Tongue weight of 499 lbs should be interesting for the FJ. I'm having the RV location install a weight distribution hitch to take some pressure off. Fortunately I only have to drive it for a long distance once. From there it sits and then gets hauled 10 mins to the storage location.
 

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Sounds right.
I tapped into the reverse light wire in the driver's side rear.
You'll tap into the brake wire behind the brake pedal for the controller.
How about a transmission cooler next?
 

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The green wire with the yellow stripe is the one behind the brake pedal to tap into. You will also need to ground the brake controller.
Run the wires through the grommet by the steering column.
Definitely need a equalizer hitch. Also replaced the stock shocks.
 

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From author Patrick McManus...

Back in 1952, a guy by the name of Milo Psinsky hooked up a trailer to his car, and all the trailer lights worked. Milo was briefly considered for sainthood, but alas, sainthood requires two miracles and not just one.

Outdoorsmen are about the only people nowadays who still use trailers: utility, camping, boat, mountain bike and snowmobile. At the moment, I am down to only three trailers: two boat and one utility/camping. The lights don't work properly on any of them. That doesn't bother me too much, because I know that's the nature of trailer lights.

A highway patrolman stopped me recently and told me that my boat-trailer signal light had indicated a left tum, and I had made a right tum.

"What's your point?" I said.

"I just thought you might be interested," he said. "I have a boat trailer that does the same thing."

"The tum signals on all boat trailers work that way," I said. "If you see a trailer signaling left, you know the driver is going to make a right. It's practically a law of physics."

"Really?" he said. "I didn't know that. Here's a ticket."

I'm not sure if trailer lights are still a major cause for divorce in this country. I believe that was the case at one time, when trailers were generally in common use. The grounds for divorce developed like this. The husband hooks up a trailer, and of course the lights don't work. Typically, there are four wires: yellow, green, brown and white. If there are more than four wires, you should immediately walk away from the trailer and call either a mechanic or a bomb-disposal unit. People have been institutionalized after attempting to hook up trailer lights with more than four wires.

Now, even though there are only four wires involved, the number of combinations in which the wires from the car can be connected to the wires from the trailer is somewhere in the neighborhood of 4,500. To find the right combination, one simply employs the process of elimination. Most of the time, the rigbt combination turns out to be Number 4,499.

The process of elimination requires two people, typically a husband and wife. The wife is usually the one stationed behind the trailer, in the position of observer. The husband either crouches or lies on his back near the respective light plugs of the vehicle and trailer. Then he begins working his way through the various combinations of wire connections.

"Okay," he shouts to his wife. "Did the left rear signal light go on?"

"No," she replies. "But the right rear signal light went on."

The man mutters something under his breath and then shouts, "Is the left light blinking now?"

"No," she shouts back. "But the right rear brake light went on."

They continue in this manner for a couple of hours, by which time the husband begins to suspect that his wife is lying to him, out of sheer malice, about which light went on. Soon their conversation degenerates into name-calling and they eventually end up in divorce court. Trailer lights are not to be taken lightly.
 

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Discussion Starter #5
At first I thought I was spammed but that was actually a very good read. Thanks for that it sounds like the "Office Space" way of thinking about trailer lights. I would go nuts if I had to wire a trailer from scratch. I could do it but worrying about wire gauge and proper protection for fuses and breakers would take me forever. I'm always abou using more than minimal code but at the same time I'd break the bank on the simplist of issues.
 

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Discussion Starter #6
BTW all wires are run and will install brake controller tonight. Checked voltages for all and it all checks out. It's a bit worrisome when you put the wife at the wheel and tell her to put car in reverse to check voltage of aux/reverse lights but she didn't run me over so thats good.

4000 lbs and close to 500 hitch weight still has me a bit nervous but thats only because I don't tow much so I'm just overthinking everything. I am getting a weight distribution hitch put on so that will take some pressure off the hitch weight.
 

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I did the job....
I started out with a big 4 conductor cable (#12) from the hood to the rear...
big 4 conductor (#12) from the brake controller to the hood.
My truck came with the 4 pin harness I wired that to the 7 pin.





Brake controller input signal - to Stop tail lights ( i know i should not do this because a fuse may blow- i don't care - I am not cutting the factory wires).
I did not tie into the tiny ass wires for the brake switch... I used the "brake light on" as the signal wire. temporary... this will cause the brake to pulse when the blinkers are on...or the hazards...
Brake Controller Output signal - to 7 pin connector.
Brake controller power Input power to 12 dc+ 30 amp breaker
Brake Controller Power Input 12 dc- / to frame ground

4 pin -to 7 pin left turn / stop
4 pin to 7 pin right turn / stop
4 pin to ground (no longer needed)
4 pin to 7 pin for running lights.
Battery + / to a 40 amp breaker / to 12 +DC + 7 pin (to charge the camper battery and break away power).
Ground wire frame bolt / 12 - vdc - on 7 pin.

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

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Discussion Starter #8
Thanks High Tech. I'm wiring up the brake controller tonight and will check for voltage once its hooked up. This summer I'm going to have to rethink my battery connections and get an under the hood fuse kit or build my own. Too many connections to the battery going on. If I can get 0-12 volts ramped up on the brake controller pin tonight I will be a happy soon to be camper.
 

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don't forget to fuse it or install a breaker. There is a post here where an FJ burned to the ground because of a non-fused power feed. I have my breakers mounted under the hood atop my fuse box plastic lid.
 

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doing this mod next.
Found threads from here very helpful.. Bought a factory 4 pin kit and "e"-vendor universal 4 -7 pin installation kit.... directions and illustrations pretty strait forward. 10 gauge is the minimum thickness for the long leads. I have 10 but will probably go up a size to 8 gauge for the battery and brake controller leads to hitch plug just to be safe (less voltage drop, less heat) and will wrap and install protective plastic sheathing to prevent issues down the road.
FWIW, the prodigy 2 controller will work with a 20 amp breaker.
 

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I just purchased a 2007 FJ. It came WITH a factory installed hitch package, but the wiring ends at the 4 pin connecter under the body attached to the frame. I need the tail that connects to that and then to a simple 4 pin trailer connector that would sit under the bumper. I see all kinds of units that are far more than I need. The trailer connector is everywhere, but I have no idea what to ask for when asking for the four pin Toyota connector. Can anyone direct me to the easiest way to get this 12 - 18" tail? And where? Thanks.
 

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Discussion Starter #13
High tech, there are 2 30 amp breakers under the hood. One for the 12 VDC feed to the rear and one for the brake controller. Just like the schematics show. I took my time and made sure that I followed the trail others before me had taken when possible. I hooked up this past weekend and towed. I had a short moment of panic when the hazards and brakes didn't work only to find out that the 15 amp under the hood fuse had blown. Easy fix. Other than that everything worked great! I was thoroughly impressed with the FJ towing ability. It was only a 22' trailer but I could barely feel it except climbing inclines but that wasn't too bad either.

5500, if you have the 4 pin kit get that wired up first and ensure it works before moving to the 7 PIN. Keep the 4 pin pigtail connectors so you don't have to cut the wires when you move on to the 7 PIN harness. Follow what others have posted and use the correct gauge of wire and you will be golden. Not hard at all. I spent more time worrying over the details rather than just following the directions.
 

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Im going to be towing a 4x8 uhaul cargo trailer for my club. I installed the receiver but didnt get the wiring. Do I have to run lights to the trailer?
 

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Discussion Starter #15
Yes, the easiest way is to get the factory wiring kit. Several vendors have them on here. Its already wired to the rear driver side underneath and then you put in two fuses. One will go in the driver side kick panel and the other goes under the hood. Hardest part was finding the right slots to put the fuses into. This will give you a 4 pin which is adequate for U-hauls.
 

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I just purchased a 2007 FJ. It came WITH a factory installed hitch package, but the wiring ends at the 4 pin connecter under the body attached to the frame. I need the tail that connects to that and then to a simple 4 pin trailer connector that would sit under the bumper. I see all kinds of units that are far more than I need. The trailer connector is everywhere, but I have no idea what to ask for when asking for the four pin Toyota connector. Can anyone direct me to the easiest way to get this 12 - 18" tail? And where? Thanks.
I'm in the same boat as Geronimo... Factory trailer wiring intact. Don't need elaborate kit... The female 4 pin connector that is in the factory mount to the left of the hitch has corroded beyond use. I could cut off the corroded plug and splice in a new female connector.
I just need to replace the tail with the 4 pin connector. Anybody know where I can buy just this tail? New would be better...
 

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I converted to the 7 pin for trailer brakes, ran heavy wire thru the frame from front to back (not hard, just fish it out of a rear opening hole). Tow a 16' Airstream and don't need weight distribution. Did add Rock-Tamers to the rear hitch for protection from flying gravel into the camper body. Have photos if anybody wants to see set up.
 
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