A isolation harness contains a set of relays; one each for the brake, turn signals, and running lights. Your bike is full of relays that control the lights, horn, and many other circuits.  In short, a relay is an electrically-controlled switch.

When installed on your bike, the isolation harness uses your signals circuits as the triggers, but it draws power for the trailer lights directly from the battery.  This means your trailer lights are running at full power and they are separated from the rest of the bike.  Even if a short developed and rendered the trailer’s lights inoperable, it would not affect the bike’s lights.

Installation

This plug-and-play isolation harness is for a four-wire trailer and a Harley.

An isolation harness can be installed on any 12 volt motorcycle. A popular relay package I often use has three components: 1) the relay package consisting of a weather-sealed epoxy package with a passel of wires, 2) a 5-to-4 converter package for use with four-wire trailers, and 3) a subharness.

The subharness, consisting of four wires terminating in a four-pin plug, is installed first. If you own an ’88 to present Gold Wing or Harley touring bike you can use a plug-and-play style subharness that plugs into your bike. All other bikes require a universal subharness which contains a set of quick taps. We’ll assume you have something other than a Harley or Wing and need to use the universal subharness because your installation will require a little more effort.

Job one is to identify which wires run your bike’s running lights, left and right turn signals, and brake. If you have added a brake light modulator or other aftermarket accessories, you may already know. It’s times like these that it pays to have the shop manual for your bike or access to an online owner’s forum.

Remove the seat from your bike and look for a wiring harness that runs toward the back of your bike. On many bikes there is usually only one wiring harness running to the lights in the back. Without the shop manual you can still figure out which of those dozens of wires are the right ones to tap. Remove your lights from the back of the bike and make a note of the wire colors for each light. All of your lights should have one color in common and that common color should be the ground side of your wiring. Locate the other color wires in the wire bundle running under the seat. You will need to pull away some of the wrapping around the harness so you can get at enough length of the wires to tap into them.

Before you start tapping, I’d advise that you take an extra step just to make sure you’ve flagged the right wires. Using a pair of pliers, push a straightpin into one of the wires until you’ve punctured the insulation. Attach a test light or voltmeter (set to a range of 20 to 50 volts) with the positive lead on the pin and the negative lead on the negative battery post. Turn on the bike to check the light you’re testing. If you’re checking a turn signal you can expect to see the test light flash on and off just light the turn signal. On a voltmeter, the needle will swing as the voltage on the circuit rises and drops. Do this for each wire and you can feel confident you’ve identified the right wires.

The subharness comes with a set of quick taps. If you haven’t used quick taps before, they’re an easy way to splice in a wire into your harness without actually cutting into your harness. A quick tap has two slots that hold the wire you are tapping and the wire you are adding. Using a pair of pliers, push the metal tab down until it penetrates the insulating jacket of both wires, then fold the plastic tab over the body of the tap to clip it shut. Do this for each of the four signal wires and you have just completed the most difficult part of the trailer harness installation.

After installing the sub-harness, you’ll plug in the 5-to-4 converter if required. You’re probably wondering, “How do I know if I need this?” The easiest answer is to check your owner’s manual or look at your wiring harness.  If you have a separate wire for brake lights and each turn signal, you have a five-wire system. If the wiring diagram in your owner’s manual shows your brake lights combined with the turn signals, you have a four-wire system. This is similar to the wiring scheme used on boat trailers and motorcycle haulers.

If your trailer is a four-wire system, you need to install the converter. Your bike has separate lights for brake and turn signals, so they can operate independently. The converter adapts the bike’s wiring so the trailer’s lights can operate properly, allowing the turn signals to override the brake lights on the trailer. Without a converter, your turn signals will only work when the brake is not applied.

With the 5-to-4 converter in place (or not), you’re now ready for the relay package. The relay has a four-pin connector that plugs into the sub-harness (or 5-to-4 converter), two power leads, and five output wires. Find a spot where you can tuck the relay package. It’s built to be weather resistant but you can usually find one little spot under the seat if you look around.

Next, run the power leads. The relay package uses power directly from the battery to operate the trailer lights.  The relay package contains a set of crimp connections and a fuse to wire to the hot lead of the relay package. Always wire in the fuse! The connectors on the package require a crimp connection. To ensure you get a good crimp, use a real crimping tool to attach the terminals, not a pair of pliers.

With the fuse and terminals wired onto the power leads, connect the relay package to your battery.  Disconnect the negative lead entirely from the battery before connecting the positive lead. This avoids a potentially dangerous situation. When working around the positive terminal, you can’t accidentally short out the battery if the ground lead is disconnected. After disconnecting the ground, connect the positive lead to the positive side of the battery, then connect the negative side, reconnecting the main ground lead.

Before you go further, it’s a good idea to check your work at this stage while everything is easily accessible. Attach a voltmeter or test light to the outputs of the relay package. The ground lead of your test device connects to the ground wire on the relay package. Connect the positive lead of your device to the wire designated for the running lights. Key the bike to the “on” position and check your test device. A test light should simply light up while a voltmeter will read a steady 12 volts on the scale. Check the other lights including brake and turn signals. Make sure the leads of these wires do not contact the ground lead while you are testing.

How did that turn out? Just fine, I’ll bet. Now you are ready to wire on a plug and button up the bike.  I’ll discuss this step in a future installment.

Photo Courtesy of Alan Cleaver

Thinking about buying a trailer, but need to get it past the home budget czar? Really like a particular trailer but find it’s just a little out of your range? Here’s a list of ways you can save money when buying a trailer. Depending on your circumstances, it is entirely possible to cut your cost for a trailer by more than half. So, I hope this helps you get the trailer you want, and a price you can afford!

Buy Off-Season

This may be the most obvious of suggestions, but making a trailer purchase in the off-season will save you money. In October, we’re still mourning the loss of fair riding weather for the year, and haven’t started looking forward to next year’s rides. Very few people are thinking about trailers. As we begin to approach riding season on the calendar we suddenly remember – Oh yeah, I guess I’d better get that trailer ordered!

Do yourself a favor and budget for your trailer purchase between November and January. There’s a good chance you will find special shipping deals, discounts on leftover models, and incentives on orders for the new year.

Buy a Complete Package

Do you need a hitch and wiring for your bike along with the trailer? You may be able to get a package deal and save money on the extras when you buy everything all at once.

Buy a Trailer Timeshare

Have you and a buddy talked about buying trailers for your future trips? If you have similar tastes in bikes, you may be able to save by splitting the cost of a trailer with your friend. Think of it as a “trailer timeshare.” People buy timeshares of beach condos, exotic sports cars, and airplanes, so why not a trailer?

When traveling together, you’ll find that a 25 cubic foot cargo trailer can easily handle the gear of two couples. You’ll also have the use of a trailer when you go off on solo trips. You’ll need to agree on a common color choice, how the trailer will be stowed, and how to allocate its use when you are not riding together. But if you find you can agree on these things, sharing a trailer means you’ll get all the trailer you want for half the money.

Make a Group Buy

Maybe you and your friend like to travel together, but you know a trailer sharing agreement would never work.  You can also save by buying with a friend or with a group if you purchase trailers from the same place at the same time. A package deal will allow a willing dealer to create some incentives for a group purchase.  Shipping two or more units to the same location can also help reduce your freight costs by as much as a third.

Terminal Pickup

Speaking of shipping, it’s possible to save a big chunk on freight by picking up your trailer at the freight terminal of the truck company handling your delivery. Often, delivery to your door is expensive because the shipping company will need to run a special truck to your house. If you have a pickup or a flatbed trailer, or access to either, picking up your trailer at the terminal will often save you $150 or more.

Make It a Vacation

I’ve sold trailers to many riders who avoid crating and shipping fees altogether by making a vacation out of picking up their trailer. Escapades are manufactured in the Virginia mountains while American Legends are made in the midwestern heartland. Mini Mates come from Pennsylvania and WAGS are in Iowa. All are great riding destinations.

Cash Talks

Dealers who accept cash or personal checks for payment may be willing to give you a discount.  They would be paying the discount to a credit card company, so why not give it to you instead? Card discount rates usually run 1.5 to 2.5 percent. Potential savings: A cash discount on a $4,000 trailer would put $100 in your pocket.

Go Color Neutral

If you’d like to have your trailer color-matched but want to keep your costs down, consider buying a neutral color. Most trailers are available at no extra cost in stock colors. Fiberglass trailers are usually available in a white or black gel coat.  Gel coat is a hard finish used to give fiberglass a finished look.  It is not as glossy as paint, but if a black or white trailer would look good with your bike, even if just for a year, you can get it painted later and spread the cost of the trailer over time.

Get Only the Critical Stuff

Finally, take a really hard look at what you absolutely need and order only the most critical things with the trailer. Most trailers have a long list of options you can bolt on to the trailer.  Many of these are cosmetic enhancements that may add to the appeal of the trailer, but don’t necessarily change its performance. Many options such as coolers, luggage racks, spoilers, chrome trim, extra lights, can all be added at a later date.  There are a few options that make sense to have installed at the factory.  For example, if the trailer you choose offers interior carpet as an option, have that installed by the factory.  It would be difficult, time-consuming, and probably more expensive to have carpet added later to your trailer.

Let’s take a real example. Let’s say you’re interested in an Escapade LE trailer (25 cubic feet, air suspension). You really want it color matched to your bike but you need to keep the price down. On an Escapade, as I mentioned above, the only critical factory-installed option is the carpeting. That’s it. Don’t let another dealer tell you otherwise. Everything else can be bolted on later. Chrome wheels? Chrome tongue? Luggage rack? These can all be added later with no problem. Stone shield? Skip that and have a car detailer install a clear stone guard on the front. Cooler? Bolt on.  Garmet bag? Bolt on. Spoiler? Bolt on. Not as easy as adding some of the other things, but it’s still a bolt on.

When you take off all the things you can add later, guess what?  A color-matched Escapade LE that would have cost you $4590 with all the popular options is now $2,865.  Later, if they’re important, you can add your accessories. But for now, the important thing is, you have a color-matched trailer for almost half the price of a full-loaded trailer.

How Do You Save?

I’ve shared a handful of ideas for saving money on a trailer purchase. What’s your strategy?

Here’s the first one: What does owning a trailer help me achieve as a rider? Why am I even thinking about owning a trailer? For most people, the answer to this question can be summed up in a word—convenience.

How much time do you spend before a trip trying to figure out how to get all your gear on the bike? How many strategies have you concocted for getting all your gear on board? Ever had a fight with your co-rider about who gets what space? Adding a trailer to your bike will almost surely eliminate the fussing and carping that precedes any long ride.

Packing up in the morning is a snap.  Toss your gear into the trailer, drop the lid, and ride off. When you’re riding with friends, you’ll make the whole trip more enjoyable for your buddies when you offer them a little extra space to pack some gear in your trailer. And you’re not limited to towing your trailer with your motorcycle. You can easily tow your trailer with any vehicle.

Pulling a trailer has some potential safety benefits, too. Trailering makes your bike more visible on the road. Your physical size on the road increases, making you easier for other vehicles to spot. Your trailer also improves your conspicuity at night with its extra lights. And, if you’re the type who stacks their bike high with gear and a co-rider, a trailer will make your ride safer simply by eliminating the top-heavy feel of your bike and restoring its balance.

Trailering with a pop-up camper makes motorcycle camping a blast. Have you passed the age when sleeping on the ground was fun, but still enjoy sitting around the campfire with other riding buddies? A pop-up camper will allow you to really enjoy this aspect of riding. Campers not only making setting up camp easier, they are also more comfortable when you need to ride out a bad weather spell. And have you priced hotel rooms lately? Even at middle-level hotels? For the price difference, you can recoup the cost of a motorcycle camper in just a year or two if you attend a couple of rallies each year or take a couple of long trips.

Trailering your gear means it will stay dry and secure. It means you won’t need to stop to put rain covers on your soft luggage, and your rain gear, kept on top of everything else in your trailer, will be easy to get to quickly without unpacking a bunch of stuff.

Your gear will be far more secure, too, than when strapped to your bike in a couple of soft bags. When you stop for lunch or call it a day, you can easily secure your trailer and its contents without spending time securing your gear or worrying about it when it’s out of sight for a few minutes.

The bottom line is this—a motorcycle trailer will help you enjoy the motorcycle touring experience and, quite possibly, encourage you to ride further and take more trips. How can that be a bad thing?

“I know this guy who knows a guy who heard that a guy was towing a trailer and it caught the edge of a bridge abutment and yanked his bike so hard it threw him over the bridge onto the Interstate and a truck runned over him.

“I heard about this guy that had a pop-up camper and it popped open whilst he was a running down the Interstate and caught like a parachute and throwed him off.”

“I heard about this guy who…”

Once you’ve heard a few of those stories, you probably start thinking, “Jeez, is towing a trailer safe?”

I understand what people mean when they ask this question, but it’s the wrong question. After all, is riding a motorcycle safe? Motorcycling is an activity that entails risk. Those who ride have judged that they are willing to accept the risks in order to enjoy the reward of riding. Smart riders do things to reduce their risks.

Similarly, towing a trailer with a motorcycle can add some risk to the act of riding. Sometimes people forget they are pulling a trailer or ride too aggressively, and when the trailer hits an unexpected bump or falls off the shoulder of the road, it can momentarily upset a bike’s handling. If you’re caught completely off guard, it might lead you to over correct and crash. On the other hand, if you’re a smart rider, you choose the right trailer, and you learn good habits, your actions can offset those risks. One of the primary aims of this site is to help you make good decisions and learn good habits.