How To Open An Infiniti Key Fob

So, you're looking to crack open your Infiniti key fob? Whether you're replacing a dead battery, troubleshooting a malfunctioning button, or just satisfying your curiosity about what's inside, this guide will walk you through the process. We'll cover the key components, the tools you'll need, and the precautions you should take to avoid damaging your valuable keyless entry device.

Purpose

Understanding the internal workings of your key fob is crucial for several reasons:

Battery Replacement: The most common reason. Infiniti key fobs, like most modern car keys, rely on a small battery to power the radio frequency (RF) transmitter. When the battery dies, your remote functions (lock, unlock, panic) will cease to work.

Button Repair: Over time, the buttons on your key fob can wear out or become damaged. Replacing the button pads or cleaning the contacts might be necessary.

Case Replacement: The plastic casing can crack or break, especially with regular use. Knowing how to open the fob allows you to transfer the internal components to a new case.

Programming Issues: While you can't typically reprogram the fob itself by opening it (that usually requires specific diagnostic tools and procedures connected to the vehicle's OBD-II port), understanding the components involved can aid in diagnosing communication problems.

General Understanding: For the mechanically inclined, simply understanding how things work is a valuable pursuit.

Key Specs and Main Parts

Infiniti key fobs vary slightly depending on the model and year of your vehicle. However, the core components remain relatively consistent. Here's a breakdown:

Essential Components:

Casing (Housing): Typically made of durable plastic, the casing protects the internal components from damage. It usually consists of two halves that are snapped or screwed together.

Printed Circuit Board (PCB): The heart of the key fob. The PCB contains all the electronic components, including the microcontroller, RF transmitter, and button contacts.

Microcontroller: A small integrated circuit (IC) that controls the key fob's functions. It receives signals from the buttons and transmits the appropriate RF signal to the vehicle.

RF Transmitter: This component generates the radio frequency signal that's sent to your car's receiver. This is how the car unlocks, locks, or activates the panic alarm.

Button Contacts: These are the conductive pads that make contact with the PCB when you press a button. They are often made of a flexible material like rubber or silicone with a conductive coating.

Battery: Typically a CR2032 or similar coin-cell battery. This battery provides the power needed for the microcontroller and RF transmitter to function.

Emergency Key (Mechanical Key): Many Infiniti fobs contain a small, physical key that can be used to manually unlock the car door in case the battery dies or the electronic system malfunctions. This key is usually hidden within the fob and can be released by pressing a button or sliding a latch.

Key Specifications:

Operating Frequency: Usually 315 MHz or 433 MHz, depending on the region and model. This frequency is crucial for communication with your car.

Battery Voltage: Typically 3V, as provided by the CR2032 battery.

Operating Temperature: Key fobs are designed to operate within a specific temperature range, typically from -20°C to +60°C. Extreme temperatures can affect battery performance and component reliability.

Opening the Key Fob: Step-by-Step

Tools Required:

Small flathead screwdriver or plastic pry tool (spudger)

New CR2032 battery (or the correct replacement battery for your model)

Clean cloth or paper towel

Locate the Release Mechanism: Examine the key fob closely. Look for a small button, notch, or sliding latch that releases the emergency key (if present). Remove the emergency key.
Pry Open the Casing: With the emergency key removed, you should see a small seam where the two halves of the casing meet. Using your small flathead screwdriver or plastic pry tool, gently insert the tool into this seam.
Work Around the Seam: Carefully pry along the seam, working your way around the perimeter of the key fob. Apply gentle pressure to separate the two halves of the casing. Avoid using excessive force, as this could damage the plastic clips that hold the casing together.
Separate the Casing: Once you've worked your way around the entire perimeter, the two halves of the casing should separate. Be careful not to let the internal components fall out.
Battery Replacement (if applicable): If you're replacing the battery, note the orientation of the old battery (the positive and negative sides). Use your fingernail or a small tool to gently pry the old battery out of its holder. Insert the new battery, making sure the positive (+) side is facing the correct direction.
Reassemble the Key Fob: Carefully place the PCB and battery back into one half of the casing. Align the two halves of the casing and snap them back together. Ensure that all the clips are securely fastened.
Test the Key Fob: Test the key fob to make sure it's working properly. Press the buttons to lock and unlock your car, and test the panic alarm.

How It Works (Simplified)

When you press a button on your key fob, the following sequence of events occurs:

Button Press: The button press completes a circuit, signaling the microcontroller on the PCB.
Microcontroller Activation: The microcontroller interprets the signal from the button and retrieves the corresponding code from its memory.
RF Transmission: The microcontroller activates the RF transmitter, which generates a radio frequency signal containing the unique code for your key fob.
Signal Reception: Your car's receiver detects the RF signal and decodes the code.
Verification: The car's computer compares the received code to the stored code for your key fob. If the codes match, the car performs the requested action (e.g., unlocks the doors).

Real-World Use: Basic Troubleshooting Tips

Key Fob Not Working?

Check the Battery: This is the most common culprit. Replace the battery with a new one of the correct type.

Clean the Contacts: If the battery terminals or button contacts are dirty or corroded, clean them with a cotton swab dipped in isopropyl alcohol.

Resynchronize the Key Fob: Sometimes, the key fob can become desynchronized with the car's system. Refer to your owner's manual for instructions on how to resynchronize the key fob. This often involves a specific sequence of button presses while inside the vehicle.

Check for Interference: Strong radio frequency interference from other devices can sometimes interfere with the key fob's signal. Try using the key fob in a different location.

Damaged Components: Visually inspect the PCB for any signs of damage, such as broken components, burnt traces, or corrosion. If you see any damage, you may need to replace the key fob.

Safety

Working with electronic devices always carries some risk. Here's what to keep in mind:

Static Electricity: The components inside a key fob are sensitive to static electricity. Ground yourself by touching a metal object before handling the PCB.

Sharp Objects: Be careful when using a screwdriver or pry tool to open the casing. Avoid applying excessive force, which could damage the plastic or your fingers.

Battery Safety: Dispose of old batteries properly. Do not incinerate or puncture batteries, as they can release harmful chemicals.

Component Damage: Avoid touching the electronic components on the PCB with your bare fingers, as this can contaminate them with oils and dirt.

By following these instructions and taking the necessary precautions, you can safely open your Infiniti key fob and perform basic repairs or maintenance. Remember to work carefully and avoid using excessive force, and you'll be well on your way to keeping your key fob in top working condition.

We have a detailed diagram of a typical Infiniti key fob's internal components available for download. This diagram includes labels for all the key components, as well as details on the PCB layout. Click here to download the diagram.