SmartPlug Power Inlet Upgrade

There are some upgrades you do because they solve a problem you already have, and other upgrades you do because you want to avoid a potential problem. The SmartPlug probably falls in the latter camp for most new Airstream owners.

SmartPlug Upgrade

The reason is that the standard electrical inlet on the side of every Airstream is pretty good. Problems like melted plugs, worn-out prongs, corrosion, and loose plug heads generally only crop up after years of use—or under challenging conditions.

But it’s the peak of summer now, and many of us are camping with the air conditioner cranked up all day long. That’s when your power cord and inlet are being strained to their utmost.

When a problem happens and you lose power on a humid day in the 90s, it’s little consolation while you’re sweltering to know that a better replacement can be added…tomorrow. So if you are the type who likes to get ahead of a potential problem, the SmartPlug is for you.

This is basically an industrial-grade replacement to the inlet that came with your Airstream. It has twenty times the electrical contact area, which means it is much less likely to get hot when the electrons are flowing at maximum. That’s its big claim to fame, because heat build-up at the plug and inlet is the cause of melted plugs.


The larger contact area for the plug means a better electrical connection, and less susceptibility to the effects of corrosion. (If you haven’t inspected and cleaned the plugs on your Airstream’s power inlet and power cord, you should soon. There’s a kit on the Airstream Life Store specifically for this purpose. Corrosion causes problems.)

There are other nice features of the SmartPlug inlet, such a blue LED that shows when there’s power, and a nice self-locking mechanism that secures the plug in place, but our big concern when considering this review was the difficulty of installing it. We figure many Airstreamers won’t want to do the upgrade if they have to pay a technician to install it, so we obtained a SmartPlug to try it out.

The instructions that come with the SmartPlug were obviously written for boaters (this was originally a marine product, which is why weatherproofing is a big selling point too). But the instructions apply equally to an Airstream.

SmartPlug installation

Basically you just remove the four screws holding the inlet in place, pull it out, unscrew the three wire attachments, and then replace with the SmartPlug using the same four screws. There’s no sealant required because it comes with a gasket, and the only tool you need is a screwdriver.

We encountered a problem initially because the original inlet wouldn’t come out. It turned out that during assembly Airstream sealed the backside of it with a huge circle of sealant, which was gluing the inlet into place. We obtained access to the inside by removing some drawers, peeled off the sealant by hand, and from there the installation was easy.

original inlet glued on back
original inlet glued on back

Attaching the wires to the SmartPlug is easy. They are color-coded (black, white, green) so even a non-electrician can connect them correctly. The wires just slip into sleeves are locked into place with an Allen wrench that is supplied with the kit. No wire cutting or stripping is necessary unless the wires are damaged. Our installation was done in about 45 minutes, of which 15 minutes were spent figuring out the mystery of the sealant on the inside.

It’s clear from handling the inlet that it’s a quality product. Even though you’ll never see the interior portion of the inlet once it’s installed, it was obviously designed by someone who wanted it to be functional and look every bit worth the price. The plastic casing on the inside is thick and nicely crafted.

The exterior is pretty snappy too, if you go for the stainless steel model. SmartPlug does offer plastic versions for the white box RV and marine markets, but we’d strongly recommend going for the stainless. It just looks great on your Airstream, and it will probably last much longer.


Plugging in is a little easier with SmartPlug. You just push the plug straight in, without twisting like the original inlet. When you plug in, two springs catch the plug and lock it into place. The stainless steel outlet cover also snaps down to grab the cord on top. Weather seals ensure that moisture won’t get in, which is important for long term prevention of corrosion.

SmartPlug Packaging

Overall, we like the SmartPlug. The only downside we can see of this upgrade is that it is a little expensive, running around $190 to 250 in the Airstream Life Store, depending on whether you have 30-amp or 50-amp, and whether you choose the factory molded cord or modify your existing cord.

Unquestionably it’s a solid upgrade, so the decision whether to go for it really depends on how much you rely on shore power, and how much you would like to avoid a power problem in the future.

Fixing mysterious electrical problems

The worst problem you can have with any vehicle is not a total failure. It’s an intermittent failure. Those little quirks that crop up but can’t be reliably reproduced can drive you batty, especially when you haul the Airstream into the dealership and they come back to you with a note: “No problem found,” or “Unable to reproduce customer complaint.”

Of these, the most common are electrical problems. Flickering LED lights, problems with the refrigerator or electric brake actuator (if your trailer has disc brakes), short battery life, and dim lights can all be symptoms of one common problem: bad electrical grounds.

In 12 volt DC wiring systems, every device (light, water pump, fan, furnace, etc.) has a 12v+ (positive) and 12v- (negative) connection. The negative connection goes to “ground” (or “earth”) in British English) to complete the circuit. Generally, all of the ground connections in a travel trailer or car end up being attached to the metal frame of the vehicle.

When the ground connectors get corroded or loose, all kinds of strange problems can occur. Electricity wants to find a path, so if the ground is poor, the current may run in unexpected ways, even backwards through a circuit. This can cause appliances to fail, work incorrectly, or intermittently.

Late model Airstreams usually have one or two external grounding points that provide the main electrical path to the frame. On vintage Airstreams the ground may be inside. Once located, these grounds can be easily checked. On a late model Airstream one is usually toward the front, possibly beneath the A-frame where the propane tanks sit. Look for a thick bare copper wire that is bolted to the frame or to a propane gas line with a small copper clamp. The location may vary—on some trailers it is located near the front curbside stabilizer jack.

If this wire looks corroded or exceptionally dirty, unscrew the clamp that holds it in place and clean up the clamp and wire with sandpaper or wire brush. The copper should be shiny where the wire makes contact with the clamp, for a good electrical connection. Don’t paint it!

There may be a second ground wire located inside the rear bumper compartment, which can be serviced in the same way. After cleaning, you can coat the area with dielectric grease (or pure silicone grease) to reduce future corrosion.

Checking the grounds is not just a good diagnostic step, it’s good maintenance that might help you avoid mysterious electrical symptoms later. Since it’s easy to do with just a screwdriver and sandpaper, considering doing this procedure once a year.

The 7-way cable on an Airstream

Most people don’t think about the fat black cable that connects the Airstream to the tow vehicle—until something doesn’t work, like taillights or brakes.

It’s called either the “umbilical” or “7-way” cable, and keeping it in good condition is important because it’s the critical link for correct operation of trailer brakes, lights, and signals.

The 7-way, explained—

Dirty 7-Way plug
Don’t let your plug look like this

Since 1989 all Airstreams have used the same wiring arrangement. (Earlier trailers may have different wiring, but typically they have long since been rewired to fit modern tow vehicles.) Each location in the 7-way plug is dedicated to a specific signal. Two of them—the 12 volt positive and 12 volt negative—supply power to keep the battery charged while towing to prevent depleting the battery while using the electric brakes. The other pins carry signals to activate the clearance lights, turn signals, brake lights, and back-up lights (if the trailer is equipped with them).

Is your cable too long?

Take a look at the 7-way cable the next time your Airstream is hitched up. Does it drag on or very near the ground? It will wear away quickly if it touches the ground during ordinary towing. You can use a bungee cord to take up the slack. (Drooping to touch the ground only in a sharp turn is okay, since that contact with the ground will be very brief.)

The cable should have enough slack so that the tow vehicle can make very sharp right and left turns in a parking lot without pulling the cable taut. If your cable is too short, you can buy an extension cable or (better) have the entire cable replaced. On vintage Airstreams, old stiff cables are common, so replacement is a good idea anyway.

When hitching up…

…double-check that the plug is inserted fully each time. Often it feels like it is in all the way when it really isn’t. To be sure, kneel down and look at the connection from the side. There are little tabs on the plug and the lid of the receptacle on the tow vehicle, which lock the plug into place. If the plug isn’t inserted fully, you’ll be able to see it from the side much more easily than from the rear, and this will ensure it doesn’t come loose while towing and make sparks on the freeway.

Avoid corrosion

Corrosion is the major cause of problems for the 7-way plug. Just a little moisture over time will result in greenish or white corrosion on the connectors, and that will cause problems like inoperable lights or brakes.

Be sure to position the plug between trips so that the head of plug is hanging downward. That will help keep rainwater from settling in the plug. At various RV stores you can find a generic “7-way plug holder” that mounts to the A-frame, which gives you a place to lock the plug when it’s not in use.

Periodic maintenance…

…for the 7-way plug on the trailer is important. Periodically you should clean corrosion from the seven spade connectors. It’s difficult to do without the right tool, so we recommend a kit available in the Airstream Life Store which includes a burnishing tool (a special file designed for electronic use), a premium electrical contact cleaner, and instructions.

You can also use the same tools to clean the connectors in the tow vehicle’s 7-way outlet, if they need a little help. Plan to do this simple cleaning job at least once a year as preventative maintenance. With the right tools it takes just a few minutes.

With those simple checks and a bit of annual maintenance, you’ll have eliminated the most common causes of problems with trailer lights and brakes.