How to Change the Battery in a Lexus Key Fob – Quick and Easy DIY Tutorial

How to Change the Battery in a Lexus Key Fob

If you want to know how to change the battery in a Lexus key fob, you must know certain details, especially about the key fob. In the 1980s, key fob technology gained popularity to open cars using sensor fusion, primarily a short-range line of sight method of authentication mechanism.

A Lexus key fob is a smart key used to start the car engine, open the trunk, lock and unlock the door handles without necessarily having to insert the key in the ignition point.

The car sensors detect the Lexus key fob signals, enabling a person to operate and drive the car.

What is a Smart Key Fob?

toyota key

A smart key fob is a digital accessibility and authorization mechanism that comes either as standard equipment or an alternative in various car models.

The smart key is a component of the car’s key fob.

How They Work?

Smart key fob uses radio waves to send and receive signals from the car owner or anyone who presses the buttons on the key to confirm their identity and presence.

There are embedded antennas that receive the signals via radio waves; the antennas are the ones that enable the smart key fob to identify its rightful owner.

Smart key fobs also operate depending on the distance; in some cars, when the key is within a range of one meter, the driver can open the door with a simple touch on the door lock, and once the driver is inside the car, they can start the car by pressing on the ignition button.

How to Change the Battery in a Lexus Key Fob: Step by Step DIY Installation Guide

How to Change the Battery Lexus

Installing a keyless entry system is not a task for the inexperienced. The majority of devices come with a car alarm, keyless entry, and other features.

These devices can be extremely complicated, with several capabilities in addition to keyless entry. Because each make and model of automobile possess its unique wiring system, having a schematic for your automobile can make the task go much more smoothly.

You’ll be able to customize the remote for specific functions as well. This must, nevertheless, be performed at the very end of the installation and cabling procedure.

Before connecting the main unit to the circuit, be sure all connections are complete.

Battery you Need

The CR2032 battery is the most popular and available Toyota key fob battery on the internet. The cost of replacing these batteries for your Lexus is roughly $5.

A Windows PC, TechStream software, and a VIM communication procedure OBD2 to USB input jerk are required to program Smart Keys on any Lexus with a Smart Key fob.

This will allow you to connect to the car’s ECU and program new Smart Keys.


Installation Material Required to Change the Battery

The devices of the Smart Key are housed in a hollow triangle piece of plastic that is wider at the peak, narrower at the base, and squared off at the apex with a half-inch-long insertion part.

A standard automobile key is also hidden on the side of the Smart Key, which you can retrieve via a release at the top. Before handing over the Smart Key to a parking lot attendant, the metal key is utilized for concierge reasons, such as closing the trunk.

The trunk cannot be accessed with the Smart Key or the inside keys once manually locked. The key fob communicates with the door locks by electromagnetic microchip but communicates with the engine immobilizer mechanism via infrared.

In general, irrespective of the nature of the system you’re trying to install, you’ll require the following items:

  • Wirecutter Stripper
  • Tape for electrical connections (black, if possible)
  • Clamps Harness
  • Iron for soldering (with solder)

Needless to add, you should exercise caution when using these instruments and wear appropriate protective gear to prevent any mishaps.

What’s the Best Way to Open a Toyota Key Fob?

key fob

In most cases, all one requires is a healthy fingernail to open the key fob. If that does not help, carefully lever it open with a small flat-headed screwdriver.

Pry lightly from multiple locations around the key fob to prevent shattering the casing.

Note that some all-in-one key fob/key pairings necessitate separating the remote from the key first.

Step By Step Guide for How to Change the Battery in a Lexus Key Fob

Step 1: Cautiously read the instructions

A handbook is included with each keyless entry system that is supplied. So, before you do anything, review it well to ensure you don’t overlook any stages.

Step 2: Unplug your car’s battery

Disconnect Car Battery

Your keyless device will need to be electrically connected to your vehicle, which will need tinkering with various electrical components.

As a result, you must first unplug your car’s battery. You take the danger of being zapped if you don’t.

Step 3. Establish the Required Wiring Connections

Examine your car’s electric system when the battery is detached. To reach the wiring, you’ll have to detach the covers beneath the steering wheel and the dashboard.

Peel several of the black wiring coverings with the stripper to see each wire.

There are a few processes to making the links themselves:

(i)Remove a small section of each wire’s insulation.

(ii)Unplug the keyless system’s cable ends.

(iii)Attach the system’s stripped cables to the vehicle’s stripped cables.

(iv) Regarding connection order, attach the parking light, activation wire, major power wire, and starter wire first, then the locking system.

(v) Return all of the wires to their initial positions after you’re done. Once everything is set, plug the power battery in.

Step 4: Put the Keyless System to the Test

It’s time to put the keyless entry system to the trial when you’ve finished installing everything. This is particularly important if you’re conducting the installation first and don’t have much technical experience.

One of several things could be wrong with the system if it doesn’t work:

(i)Your key fob remote’s battery may be depleted; replace it if this is the situation.

(ii)You can utilize an internet database to reformat your remote if it has been badly coded.

(iii)You can repair the burnt circuit yourself, but it’s a bit hard, so bringing the remote to a technician might be a wiser alternative.

Guide for How to Program a Lexus Key Fob

Programming a Lexus key fob requires some expertise and specific tools for it to be a success.

Steps Involved in Programming a Lexus key fob.

  1. Use a USB cable to attach your tablet or laptop to the OBD2 port.
  2. To switch on the gauge panel without starting the car, lift your foot from the brake pedal and push the “Engine Start” key twice.
  3. Start the TechStream TIS program.
  4. Select “Connect to Car” from the drop-down menu. The application should recognize your vehicle’s brand, date, and engine code instantly. If it doesn’t, you’ll have to enter everything manually.
  5. From the “Option” drop-down arrow, choose the appropriate one depending on your car.
  6. On the menu bar, choose the “Smart Access” feature.
  7. On the left side column, select the “Utility” option.
  8. Click “Smart Code Registration” from the drop-down menu.
  9. On the page that follows, study the descriptions and mark out each of the criteria. When you’re done, select “Next.”
  10. For new key combinations, look at the number of spaces available. Ascertain that at least one space is available. If no spaces are provided, return to the previous step and erase the key code. “Next” should be selected.
  11. Organize your keys. Switch your existing registered key with the keys to be registered relatively 30 cm away from the automobile. You won’t have enough time to get in and out of the vehicle because these processes are time-limited. One can place the new blank key on the vehicle’s top, and it should work perfectly.
  12. On the following screen, select the “Pre-Start CHK” option to check the registration process.
  13. To start the registration process, click the “Start” option.
  14. Within 30 seconds, use your authorized key to press the “Engine Start” option.
  15. Retrieve the registered key from your automobile within 30 seconds (put it on the roof). Insert the key to the automobile and use it to press the “Engine Start” option. You must hear one more beep.
  16. Put the key you’re attempting to register in the passenger seat.
  17. The words “Keycode registration is complete.” will display.
  18. Select ” Next ” or ” Exit ” to sign up for more keys, select “Next” or “Exit” to complete the process.
  19. Check that your new key can start the car, lock and unlock all doors and the trunk, and turn on the alarm system.
  20. You’re ready to go!

Some Common Problems and Solutions about Lexus Smart Key

01. Car Key Remotes with Broken Internal Contacts

Key fobs are subjected to more physical violence than most devices, which aren’t impervious to damage.

However, they can malfunction in a variety of ways. The output capacitor contacts and the keys are the two most typical points of failure.

The easiest approach to determine this on your own is to disassemble the remote and perform a full visual examination.

You ought to be able to determine whether the battery connector terminals are damaged just by looking at them, and they may also seem loose. If they are, soldering them back in place may be able to bring your broken key fob back to life.

02. Door Lock Issues

It’s very typical for Lexus door locks to fail. The good news is that you can resolve Lexus door lock issues after the root cause has been found.

If your Lexus door locks aren’t functioning correctly, you can try resetting the door lock sequence to see if the system will start working again.

Benefits of Using Key Fob Instead of Proximity Key

A smart key brings automobile technology to the next level. It’s still a keyless entry technique, but it’s a step forward from traditional proximity key remote technology.

The key fob of smart keys has a unique microchip. An electromagnetic signal transmitter in one’s vehicle recognizes the chip.

The electromagnetic signal goes through the designed transmitters in the automobile, allowing users to do tasks like unlock and lock vehicles and start the engine.

Users don’t have to click a button to unlock or lock the door when using a smart key. When the automobile detects one’s presence, it automatically opens the doors for the user.

Maintenance of a Smart Key

The first item you must check is the battery. After a year or two, a battery’s performance deteriorates.

When your key fob stops functioning, don’t be in a hurry to replace it if it costs you hundreds of dollars.

It would be best if you also were careful about where you place the key fob. It’s not a good idea to leave it in your car overnight or even in a place near the car.

If you keep the fob too close to your automobile, it will keep interacting with it, draining the battery.

Do’s & Don’ts


To configure the software on your computer, always follow the directions that came with it.

While installing a key fob, ensure the device you choose can suit your unique automobile model by doing some investigation on it.


check not to leave the key fob in your car overnight or even in a place near the car as it will keep interacting with it, draining the battery.


What is the cost of Replacing the Toyota key fob

The cost of replacing a Toyota key fob can vary depending on the specific model and year of the vehicle, as well as the cost of the replacement fob itself.

In general, the cost of a replacement Toyota key fob can range from $50 to $200 or more, depending on whether it is a basic or advanced fob with additional features such as remote start or keyless entry.

In addition to the cost of the replacement fob, there may also be additional fees for programming the new fob to work with your vehicle.

These fees can vary depending on the dealership or mechanic that performs the service.

If you need to replace your Toyota key fob, it is recommended that you contact a dealership or trusted mechanic for a quote on the cost of the replacement and programming.

How to program jeep key fob?

Change the door’s button to the “LOCK” setting while it’s still unlocked. In the ignition, set the key to the “ON” setting.

For five seconds, press and hold the “LOCK” option on your key. To check if you were effective with Jeep Key fob programming, release the key and take the key from the circuit.

Is it necessary to reconfigure a key fob upon changing the battery?

The steps involved are as follows.

  1. In the key fobs, change the batteries.
  2. Enter the vehicle.
  3. It would help if you turned the ignition on.
  4. Click the Lock option on the remote.
  5. Keep an ear out for a lock sound.
  6. Programming Additional Remotes.
  7. You should turn the ignition off.
  8. Take a step out of your car and put the result to the trial.

What is the battery size for the Toyota key fob?

The battery size for a Toyota key fob can vary depending on the specific model and year of the vehicle. In general, most Toyota key fobs use a lithium coin cell battery with a size of CR2032. However, it is always recommended to refer to the owner’s manual or consult a Toyota dealer to ensure that you have the correct battery size for your specific key fob.

How long would automotive key fobs battery last if used regularly?

The lifespan of an automotive key fob battery can vary depending on several factors such as the frequency of use, the age of the battery, and the type of vehicle. In general, a typical key fob battery can last for around 2-3 years with regular use. However, this estimate can vary depending on how often the key fob is used and the features of the vehicle that are activated by the fob.

Some vehicles may require more energy to activate certain features such as remote start or keyless entry, which can shorten the battery life. If you notice that your key fob is not working as well as it used to, it may be a sign that the battery needs to be replaced.

What can you do to be certain your car is turned off?

  • Before you turn off your automobile, be sure it’s in “park.”
  • Before leaving the vehicle unsupervised, double-check that the vehicle is indeed turned off.
  • When parking an automobile, particularly on an uphill, use the parking brake.

Can a faulty key fob prevent the vehicle from starting?

The keyless ignition system will not switch on the engine if the key fob is in the vehicle.

Also, if the battery in your key fob dies, the device will not detect when the fob is inside the vehicle and will not turn the car.

Is it possible to drive if your key fob is dead?

It depends on the specific make and model of your vehicle. In some cases, it may be possible to drive your vehicle even if the key fob battery is dead or the fob is not working properly. Some vehicles may have a backup physical key that can be used to start the engine in the event of a dead battery or a malfunctioning key fob.

However, in other cases, the key fob may be an integral part of the vehicle’s security system, and the engine may not start at all if the fob is not detected. If you are unsure whether your vehicle can be driven with a dead key fob, it is recommended that you consult your owner’s manual or contact a dealership or mechanic for assistance.

the remote features on your key chain, it’s always advisable to keep it charged just in case.


Despite its debut many decades ago, wireless and tap innovation has grown in prominence over the last few years. There are many reasons for this, ranging from advancements in technology to shifts in attitudes to the growth of crime. As you can see, using a keyless entry device has a lot of advantages and disadvantages. Nevertheless, as an asset, it’s well worth it, and if installed correctly, you’ll save a huge amount of time, and each drive will be wonderfully pleasant, efficient, and secure.

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