How to TIG Weld on a Modern Car

In many cases, TIG welding can be the best choice for automotive welding on a modern car, but there can be some definite drawbacks.

So how do you TIG weld on a modern car? The most important aspect of TIG welding on a modern car is protecting the car’s ECM and digital electronics, which can otherwise be damaged by the high frequency generated during the TIG welder’s initial voltage spike while starting an arc. TIG welding can be performed safely once these electronics are protected.

The risk factor of TIG welding on a modern car may intimidate some metalworkers into not even trying it, but as long as you take precautions, it can be done. Keep reading to learn more about the dangers of TIG welding on modern cars and how to do it right.

TIG Welding and Modern Automotive Metalworking

TIG welding is one of the most popular forms of welding in the modern automotive industry, especially when it comes to the finer points of welding repair and customization on a vehicle. MIG and stick welding are usually deemed good enough for frame work, but often a lighter, more precise touch is called for when welding other components on a modern car.

Because TIG welding lends itself to a stronger, more shatter-resistant weld than MIG or stick welding, it is the method of welding type preferred by vehicle safety standards in both consumer vehicle assembly and competitive racing.

Advantages of TIG Welding on Modern Cars

TIG welding, as a welding technique on modern cars, has many advantages over other forms of welding. The benefits of TIG welding in automotive assembly are the reason it has become the quality standard for vehicle construction.

Here are some of the benefits of TIG welding on modern cars:

• Versatility: TIG welding can be used on more types of metals and alloys than any other welding method, which allows automotive welders to incorporate stronger-than-steel exotic metals such as titanium into their builds.
• Clean, quality welds: TIG welding is the best welding methods for clean-looking welds that are showroom quality, which makes TIG welding a good choice for working on modern cars where aesthetics are a concern.
• Avoid sparks and splatter: This is a useful quality in TIG welding when working on modern cars, especially when working in an inverted position beneath the frame.
• No dealing with slag or flux: TIG welding doesn’t require having to mess with cleaning up slag
  or flux, which is convenient when trying to go for a tidy look to your weld without a lot of
  clean-up.

TIG Welding Heavy Pieces vs. Thin Pieces on a Car

Though TIG welding can be used for both types of metal, TIG welding performs a different function when welding thin metals together in a car such as patched panels versus welding thick ones, such as frame pieces.

High welding temperatures and fluctuating temperatures like the ones generated by MIG welding rigs can cause distortion and other issues with thin metals; as a result, TIG welding is usually recommended for these jobs.

While TIG welding is suitable for either thickness of metal, MIG welding rigs can get away with welding on larger, thicker pieces on a car because larger pieces act as a heat sink and are less susceptible to warping and other negative effects of heat application due to their bulk.

Risks of TIG Welding on Modern Cars

TIG welding is a great option for welding on modern cars, except for one major catch: the high frequency involved in TIG welders damages sensitive electronic equipment, such as the highly sensitive electronic control modules (ECMs) and other sensors that run your average twenty-first century car.

This means that if done incorrectly or by an inexperienced technician, a TIG welder can easily short out your project car’s main computer module or other digital components, frying the electronic system and in some cases, transforming the car into the world’s least impressive paperweight.

In order to TIG weld on a modern car without risking massive amounts of electrical damage to the car’s more delicate systems, anyone planning to TIG weld on a modern car needs to understand how high frequency welding damages electronics, and how to prevent that damage.

How High Frequency Welding Damages Electronics

The danger in TIG welding on a modern vehicle is due to the electrical noise generated by high frequency welding. During the process of welding, this high amperage current is conducted into the frame or body of the vehicle.

In most cases, this doesn’t cause any problems, especially if proper grounding has taken place prior to the start of the weld. But in some cases, rogue electricity can be conducted to the wiring harness or the car’s ECM, where the sharp spikes in voltage caused by starting a TIG arc can quickly short out the car’s electrical system.

Once a car’s electrical system is damaged by the kind of electrical pulses generated by a TIG rig, there is often no choice to repair the vehicle other than to replace the ECM or the wiring harness.

Anyone who has ever looked at what it costs to repair electrical systems in a vehicle will know how brutally expensive it can be, and a car’s electronics are never guaranteed to work correctly again after a mishap like this happens.

Results of Damaging Modern Cars with a TIG Welder

The reason that working on modern cars with TIG welders is such a harrowing ordeal for those who aren’t experienced with it is that all groups of techs have horror stories about car electrical systems being fried by an improperly grounded TIG weld.

These damages usually involve catastrophic failure of the engine control module (ECM), the car’s electrical wiring harness, or both. The replacement of these parts in a car can easily run well over a thousand dollars between parts and labor.

Even if the car can be repaired, once a car has sustained electrical damage, many mechanics know that once a car’s electrical systems have been damaged by voltage, there is likely hidden damage in the system that still hasn’t shown itself yet.

This kind of damage can greatly depreciate the value of a modern car and in many cases can keep the car from running at all unless attended to by an electrical wiring specialist, which can cost hundreds of dollars an hour to both diagnose and replace the ECM as well as reprogram it. Reprogramming of an ECM or other car computer models typically must be done at a dealer.

Protecting Electronics in Cars During TIG Welding

Despite the fact that TIG welders can cause massive amounts of damage if used improperly on a modern car, they are still the welding tool of choice for the bulk of the automotive industry. This is because, with some basic protections put into place before a TIG weld, welding can be done on a modern car without any sort of problem.

There are a variety of different methods for protecting electronic components of a modern car during a TIG weld, including the following:

• Moving car components out of the way
• Grounding the car correctly
• Using a battery surge protector
• Disconnecting the car’s battery or ECM

These methods can be used separately (or even better, in conjunction with each other) to ensure that any TIG welding done on a modern car is completed without catastrophic damage inflicted on the car’s sensitive digital systems.

Moving Car Components During TIG Welding

It seems like a simple solution, but in many cases, a part that needs to be welded on a modern car can simply be detached from the vehicle, welded at a welding bench, and refitted. This decreases the amount of time the TIG welder is in potential contact with the vehicle’s electrical systems.

Often it is easier to remove a piece for precise weldwork that can be done on a welding bench under bright lighting, rather than try to weld a part while it is on the vehicle, which often involves welding in an awkward position and, in the case of TIG welding, figuring out how to control the TIG torch pedal while you weld in said awkward position.

In some cases, if welding has to be done near the seat of the ECM, it can be a much better option to remove the ECM from the vehicle completely until the weld is complete, and then replace it. That way, there is no threat of electrical damage to the ECM unit.

Grounding a Modern Car During TIG Welding

The most important aspect of TIG welding on a modern car is making sure that the car is grounded close to the area that you’re welding on. Arguably, this step is more important than any other precaution you could take with regard to TIG welding on a vehicle.

Not only does properly grounding your weld help prevent electrical damage to the car’s digital systems, it also helps to prevent the metalworker from being accidentally electrocuted. 

Modern Cars Have Many Potential Ground Loops

While there is a greater risk to TIG welding on a modern car, modern cars also possess many potential ground loops in comparison to older cars. So as long as you are properly grounding the vehicle prior to welding, there really is no excuse for shorting the car’s electrical system.

These ground loops provide many potential grounding points to ground the vehicle prior to a weld so that the metalworker can ensure that the car is grounded as close to the welding area as possible.

Auto Surge Protectors for Automotive TIG Welding

One method that people use to protect their modern car’s electrical system while performing a TIG weld is to install an auto surge protector, which hooks into the car’s electrical system and protects it from high voltage spikes that may damage sensitive electronic equipment on the car.

These surge protectors are designed specifically to protect against electrical surges associated with damage caused by high frequency TIG welding, so even though they can be a bit pricey, they’re a lot cheaper than replacing the ECM or wiring harness on your car.

Auto surge protectors are a good thing to put into place as a complementary precaution alongside grounding the car before and during a TIG weld.

How to Disconnect the Car Battery Before TIG Welding

One way to protect your car’s electrical system before you begin a TIG weld is to disconnect the car’s battery. This can be performed easily on most vehicle models. To disconnect the car battery before beginning a TIG weld, perform the following steps after securing safety goggles and some gloves for hand and eye protection:

• Turn the key in the ignition and power the car off. Remove the key from the ignition. 
• Find the negative terminal on the top of the battery. It tends to be black in color and have a minus symbol.
• Loosen the nut at the negative battery terminal.
• Repeat this process on the positive battery terminal. 
• Make sure that the positive connector on the battery cable does not contact any metal surface of the vehicle.

Once the battery cables have been disconnected, the car no longer has power to its electrical systems and can be safely welded on without damaging any electrical components. However, there are some downsides to disconnecting a battery or ECM on a modern car.

Disconnecting the Car Battery or ECM Can Cause Problems

Despite being the best way to protect the car’s electrical system during a TIG weld or other electrical work, disconnecting the car battery or ECM in a modern car can cause a number of problems with the car related to its electronic systems. The least effect you’ll see is that you may lose the time on your car’s radio display or lose presets in your electronics system.

There are deeper electrical issues that can potentially come into play. A car’s ECM can learn to work through minor faults in the mechanical system and can operate the car fine and work through those idiosyncrasies.

But once the ECM is rebooted, the computer forgets these shortcuts and quick fixes to cumulative issues in the car’s systems, and this can cause the car to begin having problems in operation that it didn’t have prior to disconnecting the electrical system.

Many technicians get blamed for fried electronics after working on cars in repair shops, but the truth is that during repairs, the electrical system is often disconnected, and once reconnected, faults may pop up that were already present in the system, just buried under the car’s various electronic coping mechanisms.

Safety Risks of TIG Welding on Modern Cars

The largest safety risk posed to a metalworker TIG welding on a modern car is the risk of electrical shock. Electrical shock in industrial accidents can often result in serious injury and possible death.

There are a number of ways that metalworkers can protect themselves from electrical shock while TIG welding on modern vehicles:

• Disconnect the car’s electrical systems. This protects both the car and the metalworker and prevents the car from being accidentally started up while the metalworker is underneath it.
• Wear dry, insulated welding gloves in good condition. Gloves should be periodically inspected for damage or wear and replaced when necessary. Gloves should form a solid shield against accidental skin-to-electrical contact.
• Avoid touching the TIG torch electrode with either skin or damp clothing. Direct contact with the tungsten electrode on a TIG torch will result in electrical shock. It is effectively like touching your hand to a live wire.
• Inspect your tools. The TIG torch electrode should always be inspected for damage prior to a weld, as well as the welding cable and the TIG torch insulation. This insulation is important to maintain since it prevents the metalworker from accidentally touching the electrically “live” components inside the torch.

On top of secondary shock, metalworkers who use TIG torches are also at risk from primary voltage shock, which can happen when the metalworker touches “live” parts of the welder inside the insulated case or makes contact with the TIG torch’s power source.

A primary voltage shock can be 120-575 volts, more than enough current to kill even the strongest metalworker. This makes it important to take electrical safety while TIG welding seriously. 

Inverted TIG Welding

When performing a TIG weld on a car, you’ll often find yourself doing an inverted weld or welding in an overhead position. The difficult part about TIG welding while welding in one of these positions is that it can be awkward to control the pedal while also controlling the filler rod and the TIG torch. 

TIG pedal control can be achieved on an automotive weld in one of the following ways:

• Create a platform or pedal holder. If you’re having to twist yourself or work overhead with a TIG torch while welding on a car, set up scaffolding or some way to position your pedal where you can easily reach it from your welding position. Pedal holders can hold the welding pedal at a functional angle to the weld spot.
• Bring in an assistant. Having a metalworking friend adjust the pedal on your verbal commands can be an efficient way to deal with TIG torch pedal logistics on an automotive weld.
• Take advantage of TIG finger controls. These remote TIG controls allow the user to keep precise control over the amperage of the weld regardless of what your weld position is, which makes it a good choice for automotive welders or anyone who has to weld away from the welding bench.

Finger Controls for TIG Welding Modern Cars

When it comes to welding on modern cars, precision is important for both protecting the car’s electrical systems as well as making sure you end up with a clean, high quality weld at the end of the day. Finger controlled TIG torches are expensive in comparison to some workshop upgrades, but the control you get over your weld is worth the investment.

Because a modern car is so sensitive to high frequency TIG welding, the more control you have over the process, the less risk you have to take, causing electrical damage to the car’s systems.

How to Prep Car Metal for TIG Welding

In welding, preparing the metal to be welded is one of the most important aspects of the welding job, despite the fact that it is one step often overlooked by novice or shoddy metalworkers.

Because cars are both lubricated for mechanical work and exposed to tons of road dust and other contaminants, any area to be welded on the car needs to be meticulously cleaned prior to welding.

The main reason it’s vital for a TIG weld to be clean is that dirty welds introduce contaminants to the weld pool that increase porosity and otherwise reduce the strength of the resulting weld.

When you’re talking about metal pieces that need to be able to withstand hundreds of pounds of impact weight, it’s even more obvious why a clean TIG weld is important when welding on cars. If a poorly-made weld shatters during a car accident, this structural failure can subsequently lead to death or injury of anyone present in the vehicle.

To prepare metal for a TIG weld, the following steps should be performed:

• Clean the metal with a degreaser using soap and rinse; dry thoroughly. 
• Use an angle grinder or sandpaper to prepare the area for welding. 
• Saturate the area using a weld cleaner or acetone and wipe away excess. 
• Perform the weld. 

Note: The above steps are to perform a basic steel weld. For aluminum welding, the TIG preparation process is slightly different due to the oxidizing properties of aluminum. Aluminum is brushed with steel wire prior to welding in order to prevent the aluminum oxide layer that forms on its surface and access the raw aluminum underneath.

Tips for TIG Welding on Modern Cars

TIG welding is one of the best techniques to use on modern cars because of how accurate it is and how strong the welds it produces are, but TIG also has the reputation of being the most difficult method of welding to master. This is because it requires a lot of focus and fine motor coordination to maintain a steady hand while traveling the weld.

There are some basic steps to setting up a TIG welder for best results, such as fine-tuning control over heat input and adjusting the current being used on the torch, but there are other methods you can use to ensure that your automotive TIG weld is successful. Here are some tips for a higher quality TIG weld on a modern car:

• Monitor the filler rod carefully. Keep the weld pool small by only adding as much filler to the weld pool as necessary to keep the weld traveling. Pushing too much filler into the weld pool can lead to splattering or runs that can mar the surface of the metal. Drips are especially a concern when performing inverted welding.
• Take advantage of adjustable frequency control. Many types of TIG torches come with an option for adjustable frequency, which can lead to a tighter arc and a more precise weld with less heat-affected area surrounding it. This can help prevent distortion in thinner, more delicate metals.
• Try pulse welding. Like adjustable frequency control, many TIG torches come with a pulse option that gives the metalworker better heat input control and decreases the heat that builds up over the course of the weld. With a steady hand or foot, a metalworker can also pulse weld manually. This leads to a very clean “stacked dime” look to the weld.

Practice Automotive TIG Welding for Best Results

One of the biggest factors to increasing a metalworker’s skill in performing a TIG weld on a modern car is practice. With practice, a metalworker becomes more confident in their abilities and more familiar with their tools, allowing them to operate on muscle memory and perform more accurate precise welds.

TIG welding is one of the hardest forms of welding to learn and can be potentially risky to perform on a modern car if the proper steps to protect the vehicle’s electronics aren’t taken, but learning how to TIG weld is one of the most rewarding skills to know in any metalworking or welding shop.

Rather than practice on a running car, TIG metalworkers can practice running welds on scrap metal in a variety of welding positions until they are comfortable with the equipment, and if working with an assistant who is running the TIG pedal, practice allows you to refine your communication with each other for increased efficiency and accuracy.

TIG Welding on Modern Cars is Tough, But Rewarding

TIG welding on modern cars is often considered a gamble by techs and mechanics alike, and this is a response to how often techs and mechanics get blamed for a car’s electrical systems going haywire after a welding job.

But with a little preparation ahead of time and some basic safety precautions, a TIG weld on a modern car is no danger to it at all, and in fact, TIG welding can yield some of the strongest and most precise welds on a modern car body or frame.