Does Touching Battery Cables Together Reset the Car Computer?

does touching battery cables together reset the car computer

Your vehicle’s computer system (ECU) is fundamental as it monitors and regulates vital functions that enable your car to run efficiently. Sometimes the computer encounters issues that may affect your vehicle’s functionality, and when this happens, you need to reset the computer and clear all the trouble codes.

Does Touching Battery Cables Together Reset the Car Computer?

Touching battery cables together will easily drain the capacitors, your vehicle’s clock will lose memory, and you may need to reset the radio stations. Additionally, the ECU’s fault codes will be cleared, the vehicle’s drivability will be erased, AC will take some time to relearn, and all the systems requiring security codes will need resetting.

What Happens When You Touch the Positive and Negative Battery Terminals Together?

When you touch the positive and negative battery terminals, the electric current will flow from one point to another. Due to the flowing current, the wiring will heat up and eventually burn.

The wires become too hot that they damage the insulation. It is also worth noting that when the positive and negative battery terminals touch, the battery may also overheat and become damaged. This is not safe.

Touching the positive and negative battery terminals creates a surge in electric current. Since the positive battery terminal is usually non-earthed, doing so will cause the electric current to flow through your body. Additionally, touching positive battery terminals together may result in a huge spark that could easily burn the cables and terminals.

Therefore, if you do not want to risk electrocution from your car battery, it is recommended that you wear protective gloves every time you are working on the components inside the hood. You should also be careful not to touch any of the vehicle’s metal parts while handling the battery terminals.

The risk of getting electrocuted by the battery terminals increases when handling an electric vehicle (EV) or hybrid vehicle with a bigger and more powerful battery. These batteries usually have up to 400V worth of power, so you can be shocked by touching the battery terminals with bare hands.

However, whether it is safe or not to touch the positive and negative battery terminals together mainly depends on the voltage of the battery. For instance, you may touch the terminals of a 12V battery with bare hands and remain unscathed. Such a battery is only likely to harm you if any of the following happens:

  • If you touch the battery terminals with wet hands
  • If you bring any flammable substances close to the battery. Such substances can cause an explosion, especially if there is leaked hydrogen gas close to the battery.
  • If the battery has an internal problem
  • If the battery’s acid splashes on your uncovered body. Battery acid is harmful and can easily burn your skin if it splashes on you. Burn injuries can be even more devastating if the acid spills on a vital organ. 

You will most likely be shocked if you touch the positive and negative terminals of a battery with greater power than 42V. Therefore, it is best to be careful since not all cars have 12V batteries.

Which Battery Cable Should You Disconnect to Reset Your Vehicle’s Computer?

If you want to reset your vehicle’s computer, experts recommend that you start by removing the negative cable first, followed by the positive one. However, removing the negative alone should get the job done if you only want to reset the ECU. On the other hand, when reinstalling the battery cables, you should always start with the positive cable followed by the negative.

If you connect the negative cable before the positive one, it won’t arc. If you connect the negative cable first while touching any metal component of the vehicle, your body will become part of the circuit; hence arcing will occur through you.

How to Safely Disconnect Battery Cables?

Your car’s battery is undoubtedly one of the most important components of your vehicle. A slight malfunction with your car’s battery can easily leave you stranded on the road. However, like any other electronic component inside your vehicle, the battery is likely to wear out, become damaged and even stop working after some time.

When this happens, you need to know how to safely disconnect the battery to clean it or replace it with a new one. Even the slightest mistake while disconnecting your car battery can easily ruin it or cause you serious harm.

Therefore, you want to ensure that you get the procedure right to disconnect the battery cables safely without any unnecessary complications. Before you begin the process, you need to ensure that you are not wearing jewelry such as rings, watches, or bracelets.

You should also carry out the entire process outdoors and on a dry surface while wearing the right protective gear. Here is a step-by-step guide on how to safely disconnect your battery cables:

  • Switch off everything and find the battery

Before disconnecting the battery cables, you must ensure that the ignition and all electrical components are switched off. Once you switch off the ignition, remove the key. You should also leave the driver’s door open since disconnecting the battery could lock everything. If you own a manual car, ensure it is in first gear.

On the other hand, if your vehicle is automatic, ensure that it is in the ‘Park’ position. Open the hood to access the battery. If your battery is not in the hood, refer to your owner’s manual to locate it. Ensure that you remove the red plastic cover fitted on the positive terminal.

  • Disconnect the battery cables

At this stage, use a wrench to loosen the nut that holds the negative battery cable in place. You can remove the cable using your hands. However, ensure that you wear protective gloves.

Removing the negative cable first reduces the risk of sparks coming from the battery. Once you remove the negative battery cable, place it carefully on a dry surface away from the battery terminal.

Disconnect the positive cable the same way. The positive cable should not come into contact with any metal components since it has some leftover charge in its system. The vehicle’s electric circuit will be compromised if the positive cable comes in contact with any metal component circuit.

  • Remove the battery strap and remove the battery

A car’s battery is held by a metal bracket or strap. Therefore, you need to find the holding mechanism and use a wrench to loosen it. You can now remove the battery from the hood or trunk. However, be careful to avoid spilling the acid inside. Place the battery carefully on a flat surface.

  • Clean the battery terminals and contacts

After removing the battery, you may notice that the terminals have been corroded due to exposure to moisture. Fortunately, you do not need expensive cleaning equipment to clean this corrosion. You can always use some of the cleaning materials at home. For instance, mixing water with baking soda to make a cleaning solution.

Once you have made your cleaner, use a wire brush to clean the inner surface of your car battery’s cable connectors. Brush the surface until it is smooth and corrosion-free. Then, dip a toothbrush in the cleaner and clean the battery terminals. You may need to use a lot more force to clean the terminals since some of the corrosion and grime may be hard to remove.

After cleaning and drying the battery terminals, ensure that you spray some anti-corrosion grease or apply petroleum jelly on them to prevent additional rust from forming. If you skip the cleaning stage while the terminals are covered with corrosion, the engine may not start due to poor conductivity.

  • Put the battery back or install a new one

Lift your old battery or the new replacement and put it back in place. Once the battery is back, place the holding mechanism over it and tighten the nuts. Reconnect the battery cables starting with the positive cable followed by the negative one. Ensure that you tighten both battery cables. Afterward, reset the digital clock since it may not be displaying the correct time.

What Does Disconnecting the Negative Battery Cable Do?

When you disconnect the negative battery cable and unintentionally complete the circuit to the ground, there will be no current flow. This is because the ground clamp is already grounded. Therefore, disconnecting the negative battery will not cause any sparks.

What Does Disconnecting the Positive Battery Cable Do?

When the positive battery cable is disconnected, it will form an electric current with just about any metal component of the vehicle. In fact, the positive battery cable does not have to touch metal to create the electric current. It can also go through the metal tools you use while handling the battery. These tools include wrenches, spanners, pliers, and screwdrivers.

How Long to Leave the Battery Disconnected to Reset the Car Computer?

For some vehicles, it may take 15 minutes for the car computer to reset after disconnecting the battery. On the other hand, some vehicles require you to drive up to 100 miles for the vehicle’s computer to monitor all the sensors, register the results and relearn.

Sometimes it may take up to 500 miles for your vehicle to relearn the fuel values. Once you drive your car for a while, you can now connect the OBD Ⅱ scanner to check the status of the ECU. If it tells you that the ECU is not ready, you may need to drive for a few more miles. If your vehicle has the ‘not ready’ status, it will not pass the smog emissions tests.

Will Disconnecting a Car Battery Harm the Computer?

Up to date, there is no irrefutable evidence that disconnecting a car battery will harm the computer. However, you should only attempt disconnecting your car’s battery once you confidently understand the entire procedure.

If you are unsure how to navigate the entire process, leave the work to a professional mechanic. This is because disconnecting a car battery incorrectly can result in severe harm and damage to your vehicle’s components.

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