EMPs and Your Car

protect your daily driver from an electromagnetic pulse.

I’m a car guy—not new cars, mind you, but the “classic cars” of my youth. I had a front row seat for the peak of the “muscle car” era of the 1960s and ’70s; and, during my teenage years, I enjoyed turning wrenches under the hoods of Dodge, Ford and Chevrolet cars and pickup trucks. Back then, all I needed to keep them running were simple hand tools, a vacuum gauge, some feeler gauges and maybe an ignition timing light.

In those days, car makers produced models that could go from the dealer’s showroom straight to the local drag strip and compete head to head. Even so, we were always tuning or swapping out parts to get more horsepower. There were no specialized gizmos or electronic devices to hook up, and the word, “computer,” was not in the automotive lexicon. Anyone with tools and the desire to learn could build or fix anything that ran on gasoline.

In this 1972 Ford Mustang Mach 1 with the optional 429 Super Cobra Jet V8, virtually all major systems were controlled mechanically instead of with electronic signals, as they are today.

Another Kind of Race

As “gearheads” were building engines and laying down rubber at places such as Beech Bend and Pomona raceways, scientists at Los Alamos were designing and testing atomic weapons in their own race to position the United States as the top atomic superpower.

One such test was called Starfish Prime. Part of a series of high-altitude nuclear tests known as Operation Fishbowl, Starfish Prime was carried out on July 9, 1962, in the mid-Pacific Ocean. The W49 thermonuclear warhead was carried into space by a Thor launch vehicle and released to reenter the Earth’s atmosphere, detonating with an estimated yield of 1.4 megatons at an altitude of 250 miles above the ocean at 09:00 Coordinated Universal Time (11 p.m., July 8, Honolulu time).

The mechanism for a 250-mile-high-burst EMP: Gamma rays hit the atmosphere between 66,000 and 131,000 feet of altitude, ejecting electrons (which are then deflected sideways by the Earth’s magnetic field). This makes the electrons radiate the EMP over a large area. Because of the curvature and downward tilt of Earth’s magnetic field over the United States, the maximum EMP occurs south of the detonation, and the minimum occurs to the north.

At the test site on Johnston Atoll, instruments designed to capture data from the event immediately went off the scale, rendering many of the readings useless. At that same instant in Hawaii—nearly 900 miles away—300 streetlights went dark, and microwave radio links from Kauai to the other Hawaiian islands were damaged, shutting down telephone communications. The effects of this man-made, high-altitude electromagnetic pulse (or HEMP) were much stronger than scientists had anticipated; and, with critical data lost due to the underestimation of the energy released by the blast, more tests were conducted.

With the disruptive effects of a HEMP now known, elaborate testing facilities were constructed to evaluate the vulnerabilities of U.S. military fighting vehicles, ships and aircraft and to develop protective measures to prevent them from being disabled by such an event. Simulators that could mimic the electromagnetic pulse were built, and everything from battle tanks to Air Force One was put through multiple tests of increasing magnitude to ensure survivability. Over time, these experiments would be conducted on other systems of national importance, including the U.S. power grid, civilian communications infrastructure and transportation interests (including trains, semi-trucks and passenger vehicles).

A 1970s-era Ford Boss 429. These powerful engines were common on drag strips and in commercial trucks. They were much less complicated to repair and modify than even the most basic auto engine built today.

The EMP Commission

The National Defense Authorization Act of 2001 established the EMP Commission. Its purpose was to evaluate:

  • the nature and magnitude of potential HEMP threats to the United States from all potentially hostile states or non-state actors that have, or could acquire, nuclear weapons and ballistic missiles, enabling them to perform a high-altitude EMP attack against the United States within the next 15 years;
  • the vulnerability of U.S. military—and especially civilian systems—to a HEMP attack, giving special attention to vulnerability of the civilian infrastructure as a matter of emergency preparedness;
  • the capability of the United States to repair and recover from damage inflicted on U.S. military and civilian systems by a HEMP attack; and
  • the feasibility and cost of hardening select military and civilian systems against a HEMP attack.

In 2008, the commission presented a report to Congress and testified before the House Armed Services Committee on its findings. The 208-page report—Report of the Commission to Assess the Threat to the United States from Electromagnetic Pulse (EMP) Attack—included results of a series of tests performed in 2004 (an excerpt from the report is included in the sidebar to the left).

Highaltitude atomic test “Orange” was carried out on August 11, 1958. The device detonated three minutes after launch from Johnston Atoll (11:30 p.m.) and 27 miles above the Pacific Ocean. The light from the blast was visible for five minutes. While not causing the strong EMP later witnessed from Starfish Prime, high-frequency radio communications were disrupted for a short period of time.

According to this report, a small percentage of vehicles can be affected by a HEMP to some degree but, with the increased complexity and number of electronic systems and sensors in today’s vehicles, the likelihood of failure is probably higher than in those built prior to 2004. There’s been little, if any, published information on testing performed by manufacturers in more recent years, but the design and construction of these electronic systems do take electromagnetic interference into consideration. Just how effective this would be against a HEMP is not yet known.

Will Your Vehicle Survive a HEMP?

Based on the 2004 test, if a vehicle isn’t running, it might not be damaged at all—the emphasis here is on might. However, if you’re driving down the highway, things could be very different. Even if your vehicle isn’t permanently disabled by the HEMP, the engine might stall or electronic systems malfunction … leading to loss of control and possibly resulting in a collision.

Many variables can determine the effects of a HEMP: the energy released from the nuclear detonation; distance and direction from the source; the orientation of the vehicle to the pulse; and the shielding provided by metal body panels (the Faraday cage effect).

Eventually, atomic testing in the atmosphere was halted, and nuclear tests moved underground. Hundreds of nuclear detonations have taken place below the surface of Nevada’s Yucca Flat test site. These subsidence craters are the lasting testament to these tests.

A vehicle’s wiring harness is of the most concern: The conductors that run between sensors and control modules will act as antennas. When the electromagnetic field flows over them, an electric current will be induced in them. This current will be passed to the delicate electronics as a voltage spike that could be detected as nothing more than a temporary circuit anomaly; or, it might be strong enough to permanently damage the car’s electronic systems.

Improve Your Vehicle’s HEMP Survival Odds

What can you do to improve the odds of your vehicle surviving a high-altitude EMP?

Well, short of storing your vehicle inside a structure constructed to act as a Faraday cage, there’s not much you can do to guarantee it won’t be affected. However, there are devices advertised to protect your vehicle’s electrical system from an EMP. In theory, they might work.

Having replacement modules, controllers and sensors on hand is certainly possible, but keep in mind that computer modules will probably have to be programmed before they’ll work. Programming equipment is available, but be sure you have everything ready and are familiar with the process before you actually have to do it. These items should be stored in an EMP-proof container until needed.

Graphic of the Van Allen Belt

Most of the components under the hood shouldn’t suffer any harm from an EMP. Batteries, alternators, high-voltage ignition components and the wiring harness, itself, wouldn’t be affected by the transient electromagnetic field, regardless of how strong the pulse is. The same goes for light bulbs and starter motors.

Nevertheless, in many vehicles built today, the switches you think make them do what they do, don’t. Control modules receive a signal from the switch on the dash, and they, in turn, send power to the headlights or start the engine. These control modules might not survive. Spares are normally available, but they might need to be programmed to work properly.

Artist conception of a solar storm interacting with Earth’s magnetic field

Diesel-Powered Vehicles

Newer-model diesel pickups and cars—and even farm equipment and semi-trucks—are just as computerized and as vulnerable as their gasoline-powered counterparts.

While many, if not most, vehicles on the road today would still be operable, there’ll be a very limited amount of fuel to keep them running. A majority of the national power grid won’t survive what’ll probably be more than just one HEMP. An attack against the United States that focuses on taking out our power and communications infrastructure would likely include several nukes detonating at the edge of space to ensure an effective strike.

A major eruptive solar prominence observed from Skylab in 1973
The author purchased a device for under $50 that connects to the OBD2 interface port in his vehicle. When the “check engine” light comes on, it’s a simple matter to connect to the vehicle’s diagnostic port and see what the problem is via a smartphone app. In some cases, manufacturers have made it possible to access trouble codes without any special devices. For the Dodge Dakota, turning the key on and off three times without starting the engine will display DTC information on the odometer. Looking up the code online will give you valuable information needed to fix the problem.
Everything from the headlights to the power door locks is controlled by a module located by the brake pedal in the author’s Dakota. Some of the functions are starting to operate erratically; a look inside at the control circuitry shows a burnt component as the likely cause. This one component will necessitate replacing the whole module!
Behold the EMP-proof 1970 Dodge Challenger T/A: 340 cubic inches and a six-pack carburetor! If you’re going to burn up the last bit of gasoline on the planet, why not do it in “retro” style?
High-voltage ignition system components such as distributor caps, spark plug wires, spark plugs and ignition coils should be impervious to an EMP.
Each and every conductor in the wiring harness is a potential path for stray current to enter the vehicle’s control modules. Through careful routing and electrical ground-bonding, auto manufacturers take measures to reduce electromagnetic interference (EMI).
A look under the hood of today’s automobile reveals a maze of wiring and multiple control modules. Numerous sensors and controllers are scattered throughout the engine compartment. Each one adds to the complexity of troubleshooting and vulnerability to an EMP.

Other Effects of High-Altitude Nuclear Bursts

Nuclear scientists had long theorized about the possibility of the electromagnetic field of a high-altitude detonation interacting with Earth’s magnetic field. However, the Starfish Prime EMP was much larger than expected. Strong electromagnetic signals were observed from the burst, as were significant disturbances in the magnetic field and Earth currents. Energized electrons and radioactive debris were trapped in the magnetic bands that encircle the planet, creating artificial auroras reaching south of the equator for hours. Unable to escape the magnetic field, this debris would continue to cause problems long after the test.

The first commercial communications satellite, Telstar 1, was launched the next day. The delicate transistors within the relay satellite were damaged by the increased radiation from the debris cloud trapped within the Van Allen Belt (a zone of energetic, charged particles that encircle the planet and are held in place by the magnetic field). By November 1962, Telstar 1 had failed, along with at least six other orbiting satellites.

However, atomic weapons aren’t the only source of electromagnetic concern.

In September 1859, a powerful geomagnetic storm, historically called The Carrington Event, was triggered by a solar coronal mass ejection (CME). First observed by British astronomer Richard Carrington, the CME traveled directly toward Earth and made the 93 million-mile journey in slightly more than 17 hours (a typical CME takes days to cover that distance). Besides the stunningly beautiful aurora that extended as far as the equator, the solar storm struck with such ferocity that the interaction with Earth’s magnetic field created an EMP that wrought havoc on telegraph systems across Europe and North America. Were it to happen today, there would be widespread disruption of our power and communications systems.

In 2012, a solar storm of similar magnitude as the one in 1859 sent plasma and energized debris toward our planet, but it passed by with little notice. It missed striking Earth by nine days.

2008 EMP Commission Report

This is an excerpt from the Report of the Commission to Assess the Threat to the United States from Electromagnetic Pulse (EMP) Attack, Chapter 6, “Transportation Infrastructure”:

“The potential EMP vulnerability of automobiles derives from the use of built-in electronics that support multiple automotive functions. Electronic components were first introduced into automobiles in the late 1960s. As time passed and electronics technologies evolved, electronic applications in automobiles proliferated. Modern automobiles have as many as 100 microprocessors that control virtually all functions.

“While electronic applications have proliferated within automobiles, so too have application standards and electromagnetic interference and electromagnetic compatibility (EMI/EMC) practices. Thus, while it might be expected that increased EMP vulnerability would accompany the proliferated electronics applications, this trend, at least in part, is mitigated by the increased application of EMI/EMC practices.


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