Wiring A Jeep Tj For Towing

Good evening,

My daily driver vehicle is not the tow vehicle - that honor belongs to the family wagon. However, my vehicle has a trailer hitch on it, has a 2k tow capacity, and I’d like to wire it up so I can use it for short distance convenience tow trips without having to go home, switch vehicles, yadda yadda. I’m mostly thinking of chores like collecting the 560 from the storage yard before a trip or running it around town for a trip to the wash rack, those sorts of things.

The vehicle in question is a 2001 Jeep Wrangler with the 4.0 straight six. Adding a 4 pin harness should be very straightforward - it already has a harness in the rear quarter panel I can simply plug into.

Converting the 4 pin to a 7 pin isn’t that much more challenging - just have to run a power wire to the battery and ground the adaptor to the frame. I don’t need the brake output signal wire because we have the Autow brake controller on the 560.

Finally, the question: Im looking at a handful of wiring solutions to convert the 4 pin to a 7 pin. One kit comes with 3 circuit breakers for use in the power wire - a 20amp, 30amp, and a 40amp and it says “install the one you need.”

So, uh, which one do I need?

 

Since you're just using it to add lights and turn signals wouldn't it be the same amps that you Jeep lights and signals use? Probably 20amp?

 

I believe the circuit breaker is intended for the power line that runs from the TV battery to the 7 blade adapter and enables the TV to charge the 560 battery.

 

Give Cary a call to be sure.
I used the Curt 4/7pin wiring kit, same setup as you; power back from battery, autox.
Be sure to put a fuse on that close to battery, use 10ga/30a, and waterproof the Curt harness connections.

 

The CTEK D250SE charger asks for a 30 amp fuse (circuit breaker) in the manual. With that in mind, the fuse is there to protect the wire. The fuse/circuit breaker should be as close to the battery as possible to avoid any wires being pinched and causing a short and probable fire.

The wire size calculator I use is here. Based on some wire length guesses - wouldn't 10 be a bit small? This calculator is saying 6 or even 4...The 10ga would give you a significant voltage drop based on its calculation....

Funny this comes up --- I'm looking at an XJ in the same situation


View attachment upload_2023-3-21_7-15-3.png

 

The 7 pin conversion kit I’m eyeballing comes with 10ga wire. To be honest, I’m not looking for a solution that provides optimal charging output. I’m just looking to stay legal when I collect the trailer and run it to the car wash for a bath. The Jeep TJ has a short wheel base and won’t be a prime towing option for anything but errands.

I was considering skipping the power wire and just plugging a 4way into a 7way adaptor without running anything extra. But, I was advised that if a trailer has electric brakes, it is legally required to also have a power connection to ensure the trailer battery will have some juice to power those brakes in case of a breakaway. This seems silly to be because I know my 560 battery is always going to have some juice in it. But alas, just want to be legal, and all it takes is running a power wire from the battery.

 

There's that question of legal

It really depends on the length of your run. I'm always over cautious. eTrailer.com FAQ on this seems to be happy with 10 amp. You'll probably be ok with it based on that. But for a charge wire bigger is better...voltage drops are less, and greater current capacity.

But I'm a safety sally and always tend to overbuild....

 

Totally understand the inclination to overbuild. I’m also there, sometimes. On this one, I’m leaning towards not worrying about it just because the Jeep will see such light/limited duty as a tow vehicle.

 

Is that 2k with electric brakes? If you can get away with towing it unbraked I would try it. I just paid a rv shop $800 to put in 7 pin wiring and a brake controller

 

I believe it’s 2k with brakes. It’s a 21 year old Jeep, it’s a little tricky finding solid literature on it.

Either way, I can install the 7pin and wiring myself. Only cost me 120 or so for the parts from e trailer.

 

Long, - yes trailer brake regs are state by state. CA is #1500 and above must have brakes on trailer, for example.

Dirty: I agree with safety first on key equipment- with precious cargo. Murphys Law #375 is that brake will be needed just when bat-tree is dayed.

Sweeney, Craig suggested the 10ga/30a run from battrey front to rear Curt harness.
And Re-running the new power wire internally to be sure no cuts or rubs,
plus waterproofing the Curt harness which was all crusted with ice ...on picking up my CO at the Nest.
(which surprisingly to me wasnt in the Curt kit, or done proper by the ND vw indy tuner shop - my bad for not inspecting parts before or thinking out my instructions better...

This change solved the persistent blowing fuses on 12ga/15a fused line that worked fine on old 4pin tent trailer.

Sweeney; err thanks my brother...
what I think you are diplomatically saying is what Cary tells me (every time I call with a dumb question RTFM? Lol.

In my defense I added the CTEK and solar roof before picking up and so never HAD the manual...

Its been read and reread btw since...lol. Pretty slick bit of tech.

 

10 gauge will probably be just fine. As I said my tendency to overthink things like this is a tendency. I'm the guy who uses a torque wrench on just about everything. Mostly because I have the tendency to turn until it cracks, then back it off a quarter turn. 6ga is what the wire calculator says but I've never seen that actually used...

 

Yeat would be my concern....the voltage drop is probably not so much since you were still above 13 volts, should still get a charge though not as fast.

When it comes to moving angry pixies around bigger is better interms of wire size, you're not using 20 gauge wire.

 

Alright, I’ve bought and installed a 4 pin kit easy peasy.

I’ve also mounted a 7 pin kit and now I’m wiring it.

I’ve basically got 4 extra wires to deal with:

Hot 10 gauge runs to battery positive, too easy.

Ground goes to the frame. Too easy.

Blue wire coming out of the 7pin gets capped, weatherproofed, and ignored. It’s intended to go to the TV brake controller, but since we have an Autow-brake on the 560, this wire is useless to me. Too easy.

I have one more wire coming out of the 7 pin. It’s an aux wire generally intended to splice into the TV reverse light signal so the trailer can see/use the reverse lights.

Does the 560 utilize that wire in the 7 pin harness? Can I cap/weatherproof /ignore this one? Or will I be losing some functionally it I decide to not splice into the TV reverse circuit?

 

Dirty call Cary or Craig to be sure, but see the owners manual for which wire goes where in the CI 7 pin plug.

Dunno about your state regs on wiring for reverse- if its helpful- a tip; you can get away without power or reverse signal in a pinch;

By using the CI lighted frame option as backup lights by flipping the manual toggle on-off switch on frame.

That also comes in handy as a work light, powered by the CI battery.

My 12v AGM TV starter batt kept blowing the 15a fuse on 12ga wire on hookup of my pickup at the Nest...the CTEK only pulls 6A normally, so Craig says, while charging the house battery- so it was resistance in my powerline including harness, up to the trailer plug...

Craig and Cary meticulously double checked everything refusing to let me go until figured it out, with the very kewl custom rollable electric test table...*

The short term fix was to disconnect the power at the CTEK charger. I too have Autow so I was safe and legit in any state requiring brakes.

I had my VW mech friend re-run a new 10 ga power lead- all thru the firewall, internally just to be sure there were no rubbing worn spots or kinks that contributed to the old 12ga lines high resistance,
along with re- wrapping the curt 4/7 harness better, to prevent moisture there in future.

Here is how he ran the power it to battery bus vs the pos terminal, and fused it there. (See pic)

*PS: Betsy I owe you and Craig, and Craigs spouse a dinner for keeping them both at the factory wayyy past closing time on a Friday night.

 

The reverse lights on the trailer come on when I put the vehicle in reverse? I thought they only came on when I manually flipped the switch for them. But still - this tow solution is just for chores around town, not real trips. I’m good with no reverse lights on the trailer as long as everything else works.

Yes, for sure - there is a 40amp circuit breaker about one foot shy of the Jeep battery on my power line.

Say more about waterproofing the Curt 7 pin? I got mine all installed today but didn’t do anything that I would consider waterproof.

 

Used the heat shrinkable covers on wire connectors and wrap well with electrical tape.

There may be a better way some here could suggest...

 

Yes, the reverse lights are wired into the 7 pin on mine as well. Not that it much matters since you can turn them on manually.

 

Ah, ok, I’ll cut that connection and redo it tomorrow with solder, heat tube, and then a mess of tape. Good tip.

 

I guess I should pay better attention! To be fair, on the list of items taking up my mental bandwidth when I’m backing the trailer up, “are the reverse lights on” is down there in the neighborhood of “what color car was behind me when I turned off the freeway” and “if we say Australia is down under, do Australians say we are up top?”