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Create Your Own Electrical Repair Kit

Originally Published in MotorHome Magazine

It was a typical hot, humid night in Florida. We had parked on one of those funny arms that runs along the coast, thinking it would be cooler and close to the beach for a nice stroll in the morning. It was so hot and sticky you could drink the air. To move was to sweat. Sitting outside was an open invitation to every blood-sucking insect for miles around. No problem, we thought. We just turned on the generator and flipped the A/C to high. It’s part of the luxury of traveling in a motorhome, right? Everything was about as comfortable as it could get, and then I pushed the switch to raise the electric step.

Poof! Darkness! No fans, no lights, no music, no TV, no water. We had no clue what had caused a total electrical failure. All the LED lights on our foolproof sophisticated breaker panel were dead, but we knew our bank of Odyssey deep-cycle batteries was fully charged.

This was one of those electrical nightmares that motorhome owners dread. In fact, electrical problems, aside from health or total mechanical failure, are just about the worst thing that can happen. Back in the days when vehicles relied on fuses you could count on one hand, there was no auxiliary fuse panel buried in the engine compartment. No super fuses or mini fuses. Just little round AGC fuses in a block under the dash. That’s over.

So many electrical circuits control today’s high-tech motorhomes, it’s a miracle we can drive down the road without something going wrong, and when it does, you need to be prepared. We have assembled a comprehensive electrical repair box for those exciting occasions. It started with a roll of electrical tape and a $1.99 test light, and grew out of experience and paranoia. Like our first-aid kit, we hope we never need to use it, but experience tells a different story.

The first step in organizing an emergency electrical repair kit is to know your vehicle. As we dissected our own travel kit recently, we realized how many items we had that only applied to previous vehicles. They had no black boxes and still used incandescent bulbs. Today’s trend toward LED, halogen and fluorescent lights presents new problems.

The Smart Glow Fuse actually glows when it blows, making troubleshooting easier.

The Smart Glow Fuse actually glows when it blows, making troubleshooting easier.

Pulling out a fuse and replacing it is about the easiest electrical repair you can make. Finding which fuse has blown can be considerably more difficult in the dark. We have found the Smart Glow Fuse, which actually glows when it blows, makes the identification of the dead fuse much easier.

A blown fuse usually means a short or an overload. Now it’s getting more complicated, but there are tools that can isolate the problem.

The least complicated but still useful is a simple test light. The basic test probe just tells you if there are 12 volts between a ground and a source. The Innova 3420 Smart Test Light (MSRP $27.45) does about the same thing, but with internal LED lights. It will also tell you the relative power of the positive or ground you are testing. Sometimes a short pair of alligator clips can help reach a terminal or extend a wire you need to test. It’s easy to make your own.

A digital multimeter can be invaluable. A small one like the Equus 4320 (MSRP $17.96) can handle many tests. The more advanced Innova 3340 (MSRP $147.86) has additional features, including a temperature sensor and an inductive pickup clamp, though it is more complicated for the non-electrician to understand. (If you have a more sophisticated tester, chances are one of your RV neighbors will know how to take advantage of it.) A resettable fuse can be useful while you are searching for the short or overload without depleting all your replacement fuses. If a fuse does blow, putting in the next size up is not a safe solution.

Innova 3347 DMM Inductive Amp Probe

The Innova 3347 DMM Inductive Amp Probe can read the amount of current passing through a wire when plugged into a compatible multimeter.

A good tool for troubleshooting is the Innova 3347 DMM Inductive Amp Probe (MSRP $135.86). By simply clipping the probe around the wire in question, and plugging the leads into any digital multimeter, you can read the amount of current passing through that wire. This can be ideal for testing alternator output, starter and battery current draw, and other mysterious drains on your system without disconnecting them.

If a faulty alternator or battery drain is suspected, an inexpensive plug-in battery monitor like the Innova 3721 (MSRP $26.85) can give you a quick idea of what’s going on. It plugs into any cigarette lighter socket. On the AC side, you never know what’s coming out of an RV campground’s 120-volt AC receptacle, so before you blame your own system, use a plug-in AC power-line monitor, available at RV/camping stores, to see if it’s a ground or a low-voltage problem.

We can’t forget the ultimate electrical troubleshooter. Computers and their related black boxes control virtually all our vehicles, and the only way to access their information is with an OBD2 scanner and code reader. The Innova 3100 CanOBD2 (MSRP $199.99) will identify trouble codes and turn off check engine lights. The more advanced Innova 3150 (MSRP $357.13) will also diagnose codes.

With these or similar testing devices, you can usually identify an electrical problem. Repairing it can be another story, but surprisingly, when you get this far, the fix is often obvious and elementary. Electrical current is like water. It flows in predictable ways. Having the proper tools and parts can make the job go much faster.

When warmed with a heat gun, propane torch or any flame, Quick Cable Guardian Heat-Shrink connectors shrink around the wire crimped to the terminal.

Our repair kit has a small selection of 2- or 3-foot pieces of red and black wire in a few different gauge sizes. If it’s a frayed wire, you will need to splice in a new piece or tape the damaged area. Splicing is best done with quality butt connectors. We highly recommend the QuickCable Guardian Heat-Shrink connectors. These are unique in that they have a built-in heat-shrink sleeve. When warmed with a heat gun, propane torch, or any flame, they shrink around the wire being crimped and glue the ends shut for a moisture-proof permanent bond. We have never had one fail, come apart or corrode. QuickCable has a full line of virtually everything needed for a basic or professional repair kit.

Speaking of connectors, probably half of the simple electrical failures we have had over the years have been the result of sloppy work and the use of poor-quality crimp sleeve connectors that tap into the wire. They are dangerously easy to use, and designed for temporary noncritical inside connections. We call them “crud-locks.” When installed correctly, at best, they only touch two or three wires in a strand of many, and they are open pathways to moisture and corrosion. This is not the kind of connection you want on your brakelights or anything that’s subject to weather.

Properly preparing a wire for crimping to any connector requires stripping the insulation off the end. There are many ways to do this, but by far the easiest is to use a wire stripper (a knife or diagonal cutters risks cutting wires at the same time). One of the most important tools you can add to your kit is a pair of high-quality crimping pliers. A poorly crimped connector often pulls apart, and you’re back where you started.

A roll of electrical tape also is a must. We carry both black and red to identify positive and negative wires. A product called Rescue Tape can also be useful for a multitude of repairs. Some short pieces of heat-shrink tubing can make a clean protective cover on a splice or terminal connection.

Four rolls of duck tape on granite counter

Electrical tape or Rescue Tape can make quick and permanent repairs.

Once the problem has been isolated and fixed, small clamps and wire ties help to isolate wires, organize them into bundles and prevent movement. Wire is made of copper, and if you flex it enough, it will eventually break. A couple of wire ties and a 2-inch piece of split heater hose can keep groups of wires from rubbing on sharp edges.

Back in Florida, in the light of day, we found the interesting cause for our total power failure. Despite the fact that our motorhome had been carefully engineered with a 120-volt AC and 12-volt DC distribution center using quality Blue Sea marine circuit breakers to avoid the use of fuses, someone had installed a 30-amp fuse in the primary power wire leading to the bank of Blue Sea circuit breakers. Raising the electric step was just enough to overload and blow it.

All this points to a few primary preventative measures that can save time and frustration down the road. Corrosion is a major problem, especially in humid, salty climates. If you’re replacing a bulb or some other plug-in connection, a little dab of dialectic grease will prevent future corrosion. It’s available in small tubes at automotive stores. When installing accessories in your motorhome, do the work yourself if possible, so you know where to look if there is a problem. If that’s not practical, at least watch and ask questions. Use the correct-size wire for an application. Never mix insulation colors, and standardize for ground and positive wires. Use quality connectors. Tape or heat-shrink every connection. Isolate all wires from sharp edges or hot engine components. Install an auxiliary fuse box if necessary, like those made by Painless Performance or Blue Sea to avoid overloading any single circuit.

Electrical problems can be aggravating at best, and even catastrophic in some cases. Fortunately, most are preventable or repairable if you have the basic tools and parts.


 Blue Sea Systems: 800-222-7617, www.bluesea.com

Equus Products/Innova: 800-544-4124, www.iequus.com


Littelfuse: Smart Glow Fuse, www.littelfuse.com/smartglow

Odyssey: 800-538-3627, www.odysseybattery.com

Painless Performance: 888-350-6588, www.painlessperformance.com

QuickCable Corp.: 800-558-8667, www.quickcable.com

Rescue Tape: 877-847-2628, www.rescuetape.com

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