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Reset Car Computer After Replacing Battery

Reset Car Computer After Replacing Battery

To reset car computer after replacing battery is one way to do an ECU reset. So why do you need to do an ECU reset and how can it be done besides disconnecting the battery? These are just a few of the things that we are going to discuss in this article.

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Reset Car Computer After Replacing Battery: Why you Need an ECU Reset 


The capacity of your vehicle's ECU (Engine Control Unit) to store long-term data in its term memory is one of its most significant features. As you drive, the engine computers are constantly learning about how you drive your vehicle and adjusting the behavior of other modules. As a result, the car can run as smoothly as possible.


Your ECU continuously learns about your driving habits and it has the capacity to store a vast amount of data, including your trouble codes, which is incredibly useful information when diagnosing possible vehicle faults. It's important to analyze your personal data and learn how to reset your ECU during this diagnostic process


If your check engine light comes on, there's a good chance your car has an internal electrical problem that needs to be fixed. You should reset your ECU before removing any parts to ensure that replacements are completely required.


Some people believe that resetting the computer, or electronic control module, in their car would solve the problems that their engine light is indicating. It's not going to happen. The engine light indicates that a sensor has sent a signal to the ECM indicating that it is out of specification and that it needs to be tested. It may be possible to delete diagnostic trouble if you have tested and repaired the problem.


A scanner is the best way to do this, but if you don't have one, disconnecting the battery on several vehicles would suffice. In many cars, however, you can reset car computer after replacing battery to delete not only diagnostic trouble codes, but also drivability, security, and radio codes. Before disconnecting the battery, locate any codes and have them, as well as the drivability learning procedures, on hand.


Reset Car Computer After Replacing Battery: Ways to Do an ECU Reset


You can reset your Engine control modules in a few different ways and they are the following:

  • Reset Car Computer After Replacing Battery 


One way to reset computer is by disconnecting your battery cable for 2 to 3 minutes and then waiting to check if the check engine light comes back on as you reconnect the battery then starting the car. 


For the ECU to understand, drive the car for at least 10 miles; if there is an issue with your vehicle, the check engine light will come back on, and you can examine the fault code that the ECU generates.


These codes will direct you to the source of the problem, allowing you to begin removing parts in an attempt to resolve the problem. You can continue to reset your computer after installing the new parts so that the engine control can “learn” the new parts and store the new data. But take note that you have to be sure that you do not have any battery cable problem and that you have backup power on hand before you do the reset.


Here is a step by step guide on how to reset car computer after replacing battery:


  1. With a can of spray-on battery cleaner, remove any corrosion from the battery and terminals. Using a combination wrench, disconnect the negative and positive battery cables. With the post and terminal cleaning tool, clean the battery posts and terminals to ensure a good connection when you're done.The wire-brush type of tool is the strongest. When using a reamer, there's a risk of removing too much material and making a loose link.


  1. Make sure to hold the positive against the negative cable ends so they are touching but not touching the battery. Be sure to short both the negative and positive wires attached to the engine with each other after removing both terminals from the battery. Then, using a cable or insulating tape, bind them.


  1. Wait for the diagnostic information to be deleted, which should take about five minutes. The positive battery cable should be installed first, followed by the negative battery cable. Follow the manufacturer's instructions when programming any radio or security codes.


  1. Follow the necessary steps for any drivability procedures that are needed for your vehicle year and model. If you drive for 10 to 20 minutes, several vehicles can immediately go through these procedures. However, before the machine learns, you can experience a very low idle or even stalling, so it's best to get the procedure as soon as possible.Different vehicles require different procedures, but for the most part, simply driving the car would suffice.

  • Reset Car Computer through the Fuse Box


When making changes to your engine, it's also a good idea to reset the ECU. In this case, you'll need to manually reset your engine control modules via the fuse box. The fuse box is next to the battery on the passenger side.


  1. When your vehicle has fully warmed up, turn it off and unplug all fuses, then disconnect the battery to cut fuel. 


  1. After a few minutes, all of the old data should be reset, so reconnect the fuses and restart your engine.


  1. Allow your vehicle to idle for at least 10 minutes to allow your ECM to “learn” any new modifications you have mounted. Since the auto ECU is such a sensitive module, it is critical to reset it after making modifications, or the new modifications which interfere with how the engine previously worked.


There are many more ways to reset your ECU besides doing the reset car computer after replacing battery and many more reasons to do so, so resetting your car's ECU should not be a hassle. Resetting your car computer should be done if any replacements are made, such as a fuel filter or a knock sensor, as well as after any work on your car's air conditioning or diagnostics.


If you need to replace your vehicle's ECM, consult your maintenance manuals or the owner's manual.


Reset Car Computer After Replacing Battery: Possible Negative Effects When Disconnecting Car Battery 


Disconnecting your car battery will not damage your device or ECU (electronic control unit) permanently, but it can have some negative consequences. This involves, as mentioned earlier, the following effects:


  • Forgetting learned shift points. The way the transmission changes and sounds can also be affected by erasing the PCM's adaptive memory. Until the PCM or transmission control module relearns the shift changes, the transmission can not feel the same. This could take anywhere from 50 to 75 miles to complete.


  • It causes an electronic radio and clock to lose their channel settings. This is more of a nuisance than an issue, and it can be resolved by resetting the radio stations and the time.


  • Forgetting your car's perfect fuel/air mixture. For a period of time before the PCM can relearn the fuel trim changes, the engine can run poorly because the air/fuel mixture is too rich or too lean. It could take several days and 50 to 100 miles of driving for the engine to return to “normal” service.


  • The ABS (Antilock Braking System) and SIR (Supplemental Inflation Restraint) or airbag modules are both reset. This should not be an issue unless one of these modules involves a special relearn or reprogramming procedure after power lost. In that case, the malfunctioning module can disable the ABS or airbag systems.


  • Depending on your vehicle when you reset car computer after replacing battery the setting of your anti-theft system may be forgotten and you may get locked out of your car. It has the potential to reset or disable the anti-theft system. Since the anti-theft device believes someone is attempting to steal the vehicle, the engine can crank but not start. To fix the issue, you can need to perform a special relearn procedure or reprogram the anti-theft device with a factory scan tool.


  • The Climate Control module is reset. On certain cars, the module will not start working again until a factory scan tool is used to perform a special relearn or reprogram procedure. That means no air conditioning until the module is programmed with the proper commands.


  • Placed settings for power windows and/or power sunroof are lost. The power windows and/or sunroof may not operate properly until the location values have been reset using the vehicle manufacturer's relearn procedure if power to the vehicle's electrical system is retained during battery replacement.


  • The steering angle sensor settings can be lost. Following a battery disconnect or replacement, the steering angle sensor would need to be relearned.


  • On certain cars, replacing the battery necessitates using a scan tool to input the new battery information into the PCM (type of battery, battery serial number and CCA rating). Since the vehicle's charging mechanism is set to progressively increase the charging rate as the battery ages, this is required. If the charging rate is not reset to that of a new battery, the battery can overcharge and fail, or, if the battery is located inside the car, release toxic hydrogen sulfide gas into the passenger compartment.


So although disconnecting the battery will not harm your vehicle's computer permanently, it will cause it to behave differently. And if you leave your battery disconnected long enough to restart the device, the processor will forget everything it has learned.


Your ECU picks up on your driving style and learns where the best shift points are, how you like to accelerate, and even how to combine fuel and air to generate combustion within the engine

If the ECU is left without power for an extended period of time (more than 5–10 minutes), it will most likely reset. This implies that it will have to relearn everything. 


As a result, the car may not perform as you expect it to. The engine may run a little rougher, and acceleration and changes may seem “off.” Some vehicles also involve the use of a scanner to input battery information before the device can operate. These vehicles are designed to adapt to the charge rate of the battery, so providing the data for your battery will enable it to charge it correctly as it ages.


Since the car's computer, or ECU, still has some current, disconnecting the battery for a short time may not be enough to reset the ECU. After disconnecting the engine, wait at least 15 minutes to ensure the system is reset.


As mentioned earlier you can reset your car’s ECU without disconnecting the battery. If you need to reboot your car's computer without disconnecting the battery, you'll need to follow a specific set of instructions. However, since this method varies by vehicle, you might need to do some research or consult your owner's manual to determine the correct procedure for your vehicle’s needs.


Reset Car Computer After Replacing Battery: Other Frequently Asked Questions

  • Why would a car's computer need to be reprogrammed?


Reprogramming will enhance spark plug timing and fuel enrichment, as well as increase turbocharged engine pressure to extract every last ounce of horsepower. To keep your vehicle control software up to date, you'll need to reprogramme your ECM.

  • How much does it cost to reset the computer in the car?


The computer itself will cost anywhere from $100 to $1,000, depending on the make and model of your vehicle. The majority of them are found inside the vehicle's cabin, under the dashboard. Because of the reprogram that must be done after the new machine is built, labor can take an hour or two.


There are a variety of reasons why you would need to disconnect your car's battery, and one of those reasons ot to reset the car’s computer. But would it harm the computer? The answer is that there are some disadvantages. Now that you know the pros and cons when you reset car computer after replacing battery you can now plan your next steps. You can now determine if disconnecting the battery to reset your ECM is worth the hassle or whether a different path is better for your situation.