How To Open Infiniti Key Fob

This article provides a detailed guide on how to safely open an Infiniti key fob. Whether you need to replace the battery, repair a damaged button, or simply understand the internal components, this guide will walk you through the process step-by-step. We’ll cover the key specs, parts, operational principles, troubleshooting, and safety considerations.

Purpose of Understanding Key Fob Disassembly

Understanding how to disassemble your Infiniti key fob is crucial for several reasons. Firstly, battery replacement is a common maintenance task. Secondly, button malfunctions due to dirt or wear and tear may require internal cleaning or repair. Lastly, gaining knowledge of the fob's internal components can be beneficial for diagnosing more complex issues and potentially performing minor repairs yourself. Moreover, for automotive enthusiasts and DIY mechanics, understanding the inner workings of automotive electronics is always a valuable skill. This guide will provide you with the information and confidence to handle these tasks.

Key Specs and Main Parts

Infiniti key fobs, like those of most modern vehicles, utilize a combination of radio frequency (RF) and microelectronic technology. While specific frequencies may vary by model and region, the core components remain relatively consistent.

Main Parts:

External Casing: Typically made of durable plastic, often ABS (Acrylonitrile Butadiene Styrene) or polycarbonate, designed to withstand daily wear and tear. It's usually a two-part clamshell design held together by clips or screws.
Circuit Board (PCB): The heart of the key fob, housing the microcontroller, RF transmitter, antenna, and other essential electronic components.
Battery: Usually a coin-cell battery, such as CR2032 or CR2025 (check your fob for the exact type), providing power to the circuit board.
Buttons: Tactile switches that, when pressed, send signals to the microcontroller, triggering specific functions like lock, unlock, trunk release, and panic alarm. These buttons often have conductive pads that connect to the PCB.
RF Transmitter: An electronic circuit that generates and transmits radio frequency signals to the vehicle's receiver. This allows for remote locking, unlocking, and starting (if equipped).
Antenna: A small, often integrated, antenna that radiates the RF signal. Its design and placement are critical for signal strength and range.
Immobilizer Chip (Transponder): A passive RFID (Radio-Frequency Identification) chip that communicates with the vehicle's immobilizer system to verify the key's authenticity. Without this chip, the vehicle will not start. This is a security feature to prevent theft.
Battery Contacts: Metal contacts that secure the battery and provide a reliable electrical connection to the circuit board.

Key Specs (Typical):

Frequency: 315 MHz (North America), 433 MHz (Europe), other frequencies may apply.
Battery Voltage: 3V (typically).
Operating Temperature: -20°C to 60°C (typical range).

How it Works

The Infiniti key fob functions as a miniature radio transmitter. When a button is pressed, the following sequence occurs:

The button press completes a circuit on the PCB.
The microcontroller detects the button press.
The microcontroller retrieves a pre-programmed code associated with that button from its memory.
The microcontroller modulates (encodes) this code onto a radio frequency carrier wave.
The RF transmitter amplifies and transmits this modulated signal through the antenna.
The vehicle's receiver picks up the RF signal.
The vehicle's computer decodes the signal and verifies its authenticity (using the immobilizer chip if necessary).
If the signal is valid, the vehicle performs the requested function (e.g., unlocking the doors).

The immobilizer chip operates differently. When the key is inserted into the ignition (or brought within proximity in keyless entry systems), the vehicle's immobilizer system sends a radio frequency signal to the transponder chip in the key. The chip, powered by the radio frequency energy from the car, responds with a unique identification code. If the code matches what the vehicle expects, the immobilizer system allows the engine to start.

Opening the Key Fob: A Step-by-Step Guide

Tools Required:

Small flathead screwdriver (or plastic pry tool)
New coin cell battery (if replacing)
Clean, static-free work surface

Locate the Access Point: Most Infiniti key fobs have a small notch or slot, often near the key ring attachment point. This is the designated spot to begin prying open the case.
Insert Pry Tool: Carefully insert the flathead screwdriver (or plastic pry tool) into the notch. Applying excessive force can damage the plastic casing.
Twist and Separate: Gently twist the screwdriver to create a small gap between the two halves of the casing. Work your way around the perimeter of the fob, carefully separating the halves. Some fobs may have small clips that need to be disengaged. A plastic pry tool is preferred to minimize scratching.
Separate the Casing: Once the clips are disengaged, carefully separate the two halves of the key fob. Be mindful of any loose components that may fall out.
Access the Battery: The battery is typically held in place by a small clip or pressure contact. Note the orientation of the battery (+ and - signs).
Replace the Battery: Use a small screwdriver or your fingernail to gently pry the old battery out. Insert the new battery, ensuring the correct polarity.
Reassemble the Fob: Align the two halves of the casing and press them together until they snap securely. Ensure all clips are engaged.
Test: Test the key fob to ensure it functions correctly. If it doesn't, double-check the battery polarity and that all components are properly seated.

Real-World Use – Basic Troubleshooting Tips

Fob Not Working: The most common issue is a dead battery. Replace the battery with a new one of the correct type.
Reduced Range: A weak battery or interference can reduce the fob's range. Try replacing the battery or moving closer to the vehicle.
Buttons Not Responding: Clean the button contacts on the PCB with isopropyl alcohol. Ensure the buttons are making good contact with the PCB.
Water Damage: If the fob gets wet, immediately remove the battery and dry all components thoroughly. Corrosion can damage the PCB.
Vehicle Not Starting (Even with a Working Fob): The immobilizer chip may be damaged or the vehicle's immobilizer system may be malfunctioning. Consult a qualified mechanic or locksmith. Note: This usually requires specialized diagnostic equipment.

Safety – Highlight Risky Components

While disassembling a key fob is relatively safe, it's important to be aware of potential hazards:

Electrostatic Discharge (ESD): The circuit board contains sensitive electronic components that can be damaged by static electricity. Work on a static-free surface and consider using an anti-static wrist strap.
Sharp Edges: The plastic casing may have sharp edges. Handle with care to avoid cuts.
Battery: Coin cell batteries can be a choking hazard, especially for children. Keep them out of reach. Dispose of used batteries properly.
Soldering (If Required): If you need to solder any components, use proper soldering techniques and wear appropriate safety gear, such as safety glasses and a fume extractor.
High Voltage: Under *no circumstances* should you attempt to modify or tamper with the RF transmitter in a way that could increase its power output. Doing so could violate regulations and potentially cause interference with other electronic devices.

Important Note: Modifying the key fob's electronics beyond battery replacement or button repair can be complex and may require specialized knowledge and equipment. If you are not comfortable working with electronics, it is best to consult a qualified technician.

We have a detailed wiring diagram of the Infiniti Key Fob available for download. This diagram illustrates the intricate connections within the fob, showcasing the flow of signals between components. Having this diagram can significantly aid in troubleshooting more complex issues or understanding the deeper workings of the system. It's especially useful when dealing with component-level repairs, such as replacing a damaged resistor or capacitor. Download the Diagram Here.