7 Way Trailer Plug / 78 FJ40 / Install advice (1 Viewer)

[Jim S.]

Want to install a 7 way connector to my 78 40. Going to need a converter for the lights. Looking for tips on wiring this up.
Thanks, Jim

 

[WarDamnEagle]

Are you going to install a brake controller?

 

[peesalot]

identify a parking lite lead, both blinkers, stop/brake lead, then you'll have the ground, the brake controller lead, & a 12v power lead, I used a test light to poke the wires at rear harnes to determine, blink, stop, & park leads. I like to leave the plug leads long or make long pigtails so you can tie into harness somewhere easier to work , mine has a rear tank so you may not have this issue.

 

[charliemeyer007]

Poking into wires works, better to use the wiring diagram and avoid making places corrosion can start.

If you plug doesn't have a protective cover when not in use, make or buy one.

Wire it up to UHaul standard plug and pin arrangement.

How to Install Trailer Wiring | U-Haul

Do you know how to install trailer wiring? U-Haul provides trailer wiring color codes and trailer wiring diagrams. Find out about 4- to 7-pin wiring.

www.uhaul.com

 

[B y r o n]

Instead of physically splicing into the wires look into creating a pass-thru connection harness. That would mean that you place it between existing connectors and not damaging the wires.

 

[Living in the Past]

I personally would install a kit that runs a separate power wire all the back to the battery so the lights are not on your not on your factory wiring. I did this on my FJ62 with just a four pin connector. Before the switch trailer lights were dim. I have other vehicles from this century with factory installed seven pin to use on for my car hauler.

I use to tow a single axle travel trailer back in the eighties with my stock 68 FJ40. Early nineties Once towed a friend's larger twin axle trailer. I insisted we temporarily install his brake controller. After a long steep grade it gradually started down hill. Headed down hill the trailer was pushing the 40 trailer started fish tailing. If I wouldn't have had a manual switch to apply the trailer brake I'm sure it would have rolled. That was the last time I ever towed a travel trailer with an FJ40.

I am curious what your towing with a seven pin trailer plug?

Instead of physically splicing into the wires look into creating a pass-thru connection harness. That would mean that you place it between existing connectors and not damaging the wires.

I haven't done that yet but I picked up a cheap pair of used 60 series tail lights that have both sides of the plug just do that.

 

[Jim S.]

There will be a brake Controller installed. Will be towing a Canadian M101 with electric brakes. I like the idea of going back to the battery. Not clear on how to make the lights function.

 

[pb4ugo]

What vehicle are trying to wire? Are you wiring a vehicle with the separate turn and brake lights or a vehicle with a combination stop, turn and park?

 

[Jim S.]

78 40. Stop and turn are separate lights.

 

[pb4ugo]

If the trailer runs a combination light, stop/turn, park then you'll have to get a converter, or you can add lights to the trailer so it has separate stop and turn lights. If you're going to use a brake controller it needs to be wired separately with separate wire running to the plug. Like @Living in the Past mentioned, you need to be able to manually control the trailer brakes from in the cab if need be, along with adjusting the braking power.

 

[Jim S.]

I'm familiar with brake controllers. Where do I wire the converter so I don't over load the trucks wiring for the lights? I would like to wire it up further up in the harness and not back at the tail lights if possible. I should have been more explicit in my earlier post. Thanks.

 

[Living in the Past]

There will be a brake Controller installed. Will be towing a Canadian M101 with electric brakes. I like the idea of going back to the battery. Not clear on how to make the lights function.

If you were in the Phoenix area I would give you a hand. Think running a second controller just to isolate the signal for the trailer brakes is the way I would. That brake signal would come directly from the brake controller so you can apply that brake separately, not that it would be that big of a deal with a quarter ton trailer. I did have set of 84 40 series axles and bunch of other stuff in my M416. Had to slam on my brakes on the freeway. 2nd gen Sequoia didn't have an issue but could tell the trailer was there. The M416 is 500#. Guessing the Canadian version it about the same. Depending on load just be easy with electric brakes.

 

[pb4ugo]

There should be a plug for the tailights at the right rear of the 40. Just inside the corner of frame. I would probably try to tie into the harness somewhere near that rear plug, maybe disassemble the plugs and tap in them, or cut the rear harness and use butt connectors and shrink tubing. You need to ID rt. left, stop, park and a ground. Id mount the converter box and hook it up, then run the pig tail from the box to the trailer. You'll need to run wires to the rear from the brake controller, those wires will go directly to the plug. Id run those wires to the rear along the stk harness.

 

[pb4ugo]

Actually, I'd probably consider adding turn lights to the trailer. I've seen those converters fail.

 

[Jim S.]

The trailer is set up for camping with a roof top tent, probably close to 1000 lbs loaded. The trailer lights are all LEDs. I'm going to run power from the battery to charge the trailer battery. Have a junction box on the trailer and the brake control signal to the brakes will get will use that power source to apply the brakes. Clear as mud eh!! The trailer wiring is all good, works fine with my Tundra.
pb4ugo, That's what I am wanting to know, the best place to tap in to the harness. Thanks.

 

[Living in the Past]

That set would not require a controller. Basically any time brake light comes on the trailer brakes will lock up. You need a variable signal to the brakes which has to come directly from the controller.

 

[pb4ugo]

That's clear. The connector is designed for rt, left, park, brake controller, ground and to the battery for the camper.