trailer wiring (4-wire and 7-wire)

Hi again,

I have a question still related to hitches but in an electrical vs a mechanical sense this time. When I purchased a hitch on-line, I used their "accessories wizard" to choose an appropriate trailer wiring kit. It seems straightfoward enough to install (open the plastic panel on the rear driver's side and stick this T-connector between the tail light harness). The brand name of this wiring kit is called "Hoppy." The box says it is a "4-wire flat trailer connector." Sounds peachy for a lighter, smaller trailers.

Now, later, what if we are interested in towing a trailer that will be equipped with electric brakes? From what I understand, this 4-wire connector only deals with the light mechanisms (right, left, brake, tail lights). And from what I have read it seems like trailers with electric brakes have 7 wires (same as the 4, plus backup lights, electric brakes, auxiliary power). Since 4 < 7 and this "Hoppy" is 4... how to achieve support for the 7 (or at least the electric brake part of it)?

I see that there are converters (examples on: http://www.hitches4less.com/adapters.html or maybe http://www.hitches4less.com/brakematekits.html ) but it would seem to me that the 3 extra functions would just get tossed out, since the Hoppy connector only deals with the 4 lights.

So... (again brief preface: the vehicle is a 1996 Cherokee Classic that has no towing package)

(1) Does the Jeep come pre-wired to support a brake control (or, anything more than the 4-pin). It seems like this beast exists (inside a kick panel I think), but would this be only if you had the towing package?

The owner's manual mentions that electric brakes are necessary for vehicles with ABS (as this one does) but doesn't elaborate any further besides one sentence! Not much help there.

If wiring does not pre-exist, does this mean that wiring must be rigged from the trailer 7-pin's "electric brake" section into the Jeep where-ever the brake controller would be mounted?

(2) Is this "4-wire Hoppy" contraption the right or wrong adapter to have?! The "wizard" I used only showed this one available for my vehicle, so I thought it was a no-brainer. Until after I received it and then read more about different possible trailer connections. I saw ChiXJeff metioned he (I will quote: "wired a pigtail to the back of the 7 wire connector, and plugged the 4 wire into that. I added another pigtail (a 4 wire with 1 lead trimmed off) for a dedicated ground, 12V positive, and electric brakes.)" From this statement, it sounds like it is possible to somehow re-use this "Hoppy" in a 4-wire and a 7-wire application. As I don't understand some of the terminology above, I'm not really sure what's going on in that description (I guess I'm more of a visual learner).

Of course I would never try these things myself, and would ask a mechanic or an RV place to do this. I would like to better grasp the workings behind this, and know did I buy the correct wiring kit in the first place (so I can return for a refund if not!)

(3) For those of you who have wired your own trailer kits, where did you route the wires? I have not even opened the plastic panel yet to see if there are some choices from there, but would the wires go somehow through the undercarriage of the Jeep, or perhaps through one of the rear light enclosures?

I guess not only am I not too mechanically inclined, neither am I too electrically inclined. Oh well... that just means there's more that I can learn!

Again, thanks for any information you may impart, or your own experiences with this (or a similar) type of setup.

there is an adapter from Hoppy and the other trailer wiring places that will plug into the 4 flat and leave the 3 pigtails for the brake, etc. check this link http://www.naxja.org/forum/showthread.php?t=53327&highlight=trailer+wiring you may have the one with trailer harness and the other end for the brake controller is up front I'll try and find it for you, John

I built my own equivalent of what John is referring to. The Hoppy 4 wire is handy for getting the basic brake/turn signals and tail lights, I added a constant 12v, electric brakes and replaced the ground.

I also rigged mine with connectors so that I could remove it while off-roading easily, and put it back on afterwards.

Edit: Oops..... missed the reference to my own post early.

Yes, you can (and probably should) use the Hoppy adapter. You'll end up using the left brake/turn, right brake/turn and taillight leads, and wire in your own 12v constant and electric brake lead. I also wired my own ground (ignoring the one coming out of the Hoppy) back to the battery to handle the increased current from the electric brakes.

I am going to be doing the same thing this weekend only on our Durango. Check out this link on Pirate that shows how to wire up a brake controller on a vehicle without the factory tow package. I purchased a Tekonsha Prodigy brake controller and they also have instructions on their site. I have the Hoppy 4 pin flat - 7 pin RV converter that I will be using. Good luck! :repair:

Yup, read the Pirate post.
Go with the first part you listed, plug your 4 way into it, hook up the white ground wire, the blue is for the brake controller, the black for the 12V and the purple is auxillary. All the details are in the Pirate post, and it is not as difficult as it sounds.
None of the XJ's came prewired for a controller. I mounted mine to the right side of the steering column.
I actually mounted my 7 way connector in my factory rear bumper. Got a hole saw and went to town.
Yes, I do tow with it. I work for an RV dealership and I pull trailers to RV shows.
Something like this.

Everybody,

Thanks for your replies and links. I have not had access to a computer for several days, but printed out and read over the pirate4x4 document, and the Tekonsha brake control document.

It sounds like I should keep the hoppy 4-pin, and stick it into a 7-pin adapter. The other important wires (brake controller, auxilary power) will be wired into the 7-pin adapter.

I did a brief image in MS Word, which is really a plagiarized version of the pirate4x4 picture with the added "Hoppy:"



Now a few more questions, for those who don't mind:

1) Is it OK to use the negative battery terminal as the ground for the brake controller? The Tekonsha document showed this in their wiring legend.

2) What and where is the stoplight switch? It sounds to me like it is related to the light in the rear that is lit when pressing the brake pedal. Is it readily visible and identifiable if I peek under the steering column?

3) We have a 7-wire adapter above; but where is the seventh wire? From what I have read, it sounds like this would be a wire that is tied to backing-up the trailer. But I don't see where the comes from anywhere within the vehicle.

4) What were your strategies for routing the wires, from battery/breakers to the brake controller? And from the battery/breakers and brake controller to the 7-pin adapter in the back? Inside, around the edges of the car? Via the undercarriage (sounds risky)? The 4x4priate document had some descriptions for other types of vehicles, but wondering how some of you folks did it for your Jeeps.

Any recommended place(s) to mount the circuit breakers in the region under the hood?

Again, thanks for everybody's experiences. It's great to know (and see) what folks have been doing to tow the trailers that have electric brakes. Regardless if I end up doing it or not, it's interesting knowledge. The 4x4pirate link helped me understand the wiring concept a little more. And that the next vehicle I purchase for a towing use will already have this stuff pre-wired and pre-mounted!

My dad owns 3 RV dealerships and ive worked in and around them for several years. Any trailer heavy enough to have electric brakes is probably too heavy to pull with the XJ. OTHER THAN say a flatbed trailer that weighs 2000 lbs. A 6000 lb travel trailer is going to push and pull that jeep all over the road.

oang said:

1) Is it OK to use the negative battery terminal as the ground for the brake controller? The Tekonsha document showed this in their wiring legend.

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I wired up our Durango last weekend. This is how I did mine.

oang said:

2) What and where is the stoplight switch? It sounds to me like it is related to the light in the rear that is lit when pressing the brake pedal. Is it readily visible and identifiable if I peek under the steering column?

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Directly behind the brake pedal. When you press on the brake pedal, it hits a plunger in the switch causing the brake lights to come on. I haven't looked at the wiring on the XJ so I can't say for sure which one is the cold side but can look it up in the FSM if you have trouble.

oang said:

3) We have a 7-wire adapter above; but where is the seventh wire? From what I have read, it sounds like this would be a wire that is tied to backing-up the trailer. But I don't see where the comes from anywhere within the vehicle.

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I didn't hook up the auxillary wire. I'm guessing that it is for accessories such as interior lighting on an enclosed trailer. I could be wrong about this one.

oang said:

4) What were your strategies for routing the wires, from battery/breakers to the brake controller? And from the battery/breakers and brake controller to the 7-pin adapter in the back? Inside, around the edges of the car? Via the undercarriage (sounds risky)? The 4x4priate document had some descriptions for other types of vehicles, but wondering how some of you folks did it for your Jeeps.

Click to expand...

I zip tied the wires (neatly packaged in flexible plastic conduit) from battery-breakers to the hood latch cable in the Durango. From the breakers-controller, I went in through an existing grommet and did the same under the dash. From the trailer plug to the controller and breakers, I came back inside the body through a grommet for the brake light wiring and routed the wires under the plastic side moulding up to the front.

oang said:

Any recommended place(s) to mount the circuit breakers in the region under the hood?

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I mounted the circuit breakers on the firewall pretty close to the drivers side. Just make sure there isn't anything behind where you want to mount them. One other consideration is that you aren't going to lean on them when you are working under the hood. I would imagine that it wouldn't feel to good to short across the two terminals with your body.

oang said:

And that the next vehicle I purchase for a towing use will already have this stuff pre-wired and pre-mounted!

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Amen! It isn't really hard to add all of the extra stuff, just time consuming. Well worth the extra cost IMO!

olivedrabcj7 said:

My dad owns 3 RV dealerships and ive worked in and around them for several years. Any trailer heavy enough to have electric brakes is probably too heavy to pull with the XJ. OTHER THAN say a flatbed trailer that weighs 2000 lbs. A 6000 lb travel trailer is going to push and pull that jeep all over the road.

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I disagree with most of that. Yes, a 6000lb trailer will push an XJ around, but there are many lighter trailers that have brakes. That one I posted a pic of weight about 3500lbs dry. We sell many tent trailers in the 2-3k lb range with brakes. If they are there, they should be used.

The 20amp breaker should be a self-resetting type, not the style where you need to get out and push a button to reset.
Smaller trailers can have electric brakes, but do not exceed the CGVW for the XJ, I've seen more than a few wrecks where the tow vehicle was too small for the trailer being towed. Spring bars and sway control are important safety items.
The seventh wire on my sisters 26' is for back up lights.
Where in California are you located?
Have fun,
Tom

olivedrabcj7 said:

Any trailer heavy enough to have electric brakes is probably too heavy to pull with the XJ.

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I have to disagree. I've been pulling trailers since I was 16 (hint: Richard Nixon was president at the time!). I used to pull a boat behind a 1/2-ton pickup. The boat and trailer weighed a total of about 1,200 lbs. The trailer didn't come with brakes, but I added them. I would add brakes to any trailer that weighed more than about 1,000 lbs. total weight, ESPECIALLY for pulling behind an XJ.

Hi All,

These responses are interesting! Thanks for the tips and personal experiences.

I guess I should clarify that if I decide to hook up a trailer to the Cherokee, it would definitely be a "small" cargo trailer, not a travel trailer, or a pop-up.

Originally, I was thinking of a mid-sized container (17' long, 7' wide, 7'6" tall, curb weight of 1700 lbs). But now I am thinking of something roughly around the dimensions of a 10' Haulmark Cub trailer (13' 4" long total, 6'8" wide, 6'9" tall, curb weight of 1000 lbs). Its payload weight is 1980 lbs, and I would likely not be transporting stuff to that capacity. Even though this type of trailer (single-axle) of any brand never comes standard with brakes, I would (if not by law, then by my not trusting my vehicle's braking system to handle any additional load) insist on an electric brake package. Although I've never personally felt it on the road, I've heard enough stories about how crummy the Cherokee's rear braking is that I would want additional stopping power for any size object I would be towing.

Boatwrench has brought up the notion of spring bars (is that equivalent to weight distribution bars?) and sway control. This is of import to me, because at some point, this hypothetical trailer may be used for long-duty highway transport, and I'd like anything that can alleviate a sway situation. For a trailer of the size I described above, is the "dual cam" sway control worth the extra $400 (although it does come with weight distribution bars, which dual cam requires anyways), or is the "friction" variety sufficient - at least in one's own experiences. From looking at usenet posts, it seems "dual cam" is preferred, but it's always in the context of 20'+ (usually travel) trailers. I'll probably ask some guys at the RV store about this, though I think the guys at the store around here will state "dual cam" mostly for the purpose of seeing a bigger possible sale from the semi-informed consumer.

Now, to the specific Cherokee information. As I mentioned earlier, I have a 1996 Cherokee with no tow package. But I peeked under the steering wheel and there is this turquoise wire labeled with tape as "Electric Brake." I believe it connects to some unknown adapter in rear hatch where the light wiring (the "Hoppy") goes. That seems strange to me; why provide an electric brake wire for a vehicle that's not tow-ready? What kind of adapter would fit into the other end (or maybe it's easier just to splice that wire directly into the 7-pin adapter).

I may need some help for anybody who knows the brake wiring. I think I found the assembly itself- a declippable harness again under the steering column (not labeled). I only hope it is the right harness - I detached it and pressing the brake pedal didn't illuminate the rear lights. If this is it, does anybody know which is the stoplight switch? The harness has wires of these colors (2 rows of 3 columns):

(top) black - pink - blue
(bottom) pink/white - white - yellow/red

I was thinking the other way to figure this out is to buy a test light, touch it to each of the contacts one at a time, and depress the brake to see which one lights up only when the brake is down.

As for the self-resetting breakers, is this something I can just pick up in a home improvement store, general electronics, or generic auto parts store? Or I guess I could buy these online, although I haven't seen if shipping is more than the parts themselves!

spaulman's description of routing the wire from the battery inside seems to be the way to go. But it looks like routing might need to take into account the fact that the heat produced in certain areas under the hood might melt the wire sheaths? I was thinking of routing the wires (from the battery) directly towards the windshield (towards the wiper fluid container, then across over to the driver's side and into the "grommet(?)" where the hood release wire comes in.

Boatwrench, I am currently located in Petaluma, California. But probably not by the end of the year. It's too expensive to make any kind of realistic home purchase here unless you've got an pre-established amount of equity (ie: owned property here before 2003) or got lucky being a start-up company bought out by a larger corporation. So already, I'm batting zero for two.

Although I'm still speculating whether or not I'm really going to go do this, I'd like to be as well-informed as possible so as not to endanger myself or others on the road. As always it is good to hear about others' towing experiences, because there's really no other way to consider the various equipment and situational scenarios - short of me actually going out and towing something around myself. But in the meantime, I still prefer to hear how others have dealt with the towing situation. Thanks again for everybody's responses.

I work at an RV dealership, in the parts department, so you can take this for what it's worth.
I think the Dual Cam would be overkill for you. They are generally geared for larger trailers. I would suggest getting a tandem axle trailer, it will resist sway much better than a single axle unit. Spring bars (or a weight dist. setup) would be a good idea. They will help keep everything level and resist a lot of sway. If you start with that, and it's not enough, you can add a friction sway control or upgrade to the Dual Cam if you want to.
As far as that brake wire, manufacturers will often run the wiring and just tie off both ends. That way, the hard part is done at the factory, but most people never see the wiring.
When you get a brake controller, do yourself a favor and spend the extra money on the Prodigy, it is, hands down, THE BEST controller out there. You will be hard pressed to find anyone that will disagree with me. Someone online had them for $99, but I can't remember who.
HTH

olivedrabcj7 said:

My dad owns 3 RV dealerships and ive worked in and around them for several years. Any trailer heavy enough to have electric brakes is probably too heavy to pull with the XJ. OTHER THAN say a flatbed trailer that weighs 2000 lbs. A 6000 lb travel trailer is going to push and pull that jeep all over the road.

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In CT any trailer over 2000 pounds is supposed to have brakes. The XJ is rated to tow 5000 pounds.

Just FYI, my 2000 XJ had a factory wire harness tucked behind the spare by a previous owner. I ran it down through the gromet in the body just in front of the bumper. The hole is already there with a solid center gromet in it and the factory trailer harness had a mtching gromet already on the wires. I hate trailer harnesses dangling out the hatch...

Ogrebonz said:

Just FYI, my 2000 XJ had a factory wire harness tucked behind the spare by a previous owner. I ran it down through the gromet in the body just in front of the bumper. The hole is already there with a solid center gromet in it and the factory trailer harness had a mtching gromet already on the wires. I hate trailer harnesses dangling out the hatch...

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Can anyone else confirm the gromet being there? I'm trying to run the wiring on my 97 SE with a OE receiver. Not sure if it was factory or dealer installed, the build sheet doesn't mention the receiver or a towing package.

http://www.naxja.org/forum/showthread.php?t=982057 post #5, mentions a gromet disk behind the driver's tail light assembly, can anyone confirm that either?

The grommet was there on my 96, I had to remove it to put the wiring in properly. I'm hoping to find another grommet with a cable hole to seal it up, if not, pipe insulation and e-tape + silicone it is.