DIY Programming Your 2004 Jeep Cherokee Key Fob

Lost your key fob or need an extra one for your 2004 Jeep Cherokee? Heading to the dealership for a replacement and programming can be costly. While official procedures often require specialized (and expensive) tools like a DRB III scanning tool, there’s a way to program your key fob yourself using readily available and affordable equipment. This guide provides a step-by-step method to program a 2004 Jeep Cherokee Key Fob at home, potentially saving you time and money.

This method is based on injecting commands directly into your vehicle’s PCI bus via the OBD2 port, a process successfully tested on a 2004 Jeep Grand Cherokee WJ. It leverages the Remote Keyless Entry (RKE) system, which is part of the Passenger Door Module (PDM) in your Jeep. The RKE system has four memory slots, allowing you to program up to four different key fobs. This DIY approach is especially useful if you don’t have a currently programmed key fob available.

Understanding the System and Required Tools

Before we begin, let’s clarify a few key components. Your Jeep Cherokee’s remote keyless entry system communicates through the vehicle’s computer network. The OBD2 port (On-Board Diagnostics II), usually located under the dashboard, provides access to this network. We will use an ELM327 based OBD2 interface – a small, inexpensive device that plugs into this port – to send commands to your Jeep. To communicate with the ELM327 interface, you’ll need a computer with RS232 terminal software (many free options are available online).

Here’s what you’ll need:

• 2004 Jeep Cherokee Vehicle: This procedure is confirmed to work on 2004 Grand Cherokee WJ models and likely applicable to 1999-2004 models.
• New Key Fob: Purchase a compatible key fob for your 2004 Jeep Cherokee.
• ELM327 OBD2 Interface: This is the hardware interface that bridges your computer to your Jeep’s OBD2 port.
• RS232 Terminal Software: This software allows your computer to send commands to the ELM327 interface. Examples include PuTTY or Tera Term.
• Laptop or Computer: To run the terminal software and communicate with the ELM327.

Step-by-Step Programming Guide

Follow these steps carefully to program your 2004 Jeep Cherokee key fob. Ensure your Jeep’s ignition is turned to the “ON” position, but the engine is OFF (KOEO – Key On, Engine Off) throughout this process.

Step 1: Setting Up the ELM327 Interface

We need to configure the ELM327 interface to properly communicate with your Jeep. Open your RS232 terminal software and connect to the ELM327 interface (refer to your ELM327 documentation for connection details). Once connected, enter the following commands one by one, pressing “Enter” after each command. These commands set up the ELM327 for communication:

AT L1
AT H1
AT E1
AT SP2
AT RA A1
AT SH 24 A1 31

Let’s break down what these commands do:

• AT L1: Turns line feeds ON for better readability of responses.
• AT H1: Turns headers ON, which is necessary for sending command headers.
• AT E1: Turns echo ON, so you can see the commands you are sending.
• AT SP2: Sets the communication protocol to VPW (Variable Pulse Width Modulation), the protocol used by your Jeep.
• AT RA A1: Sets the receive address to A1, allowing you to view responses from the Passenger Door Module (PDM).
• AT SH 24 A1 31: Sets the header bytes to 24 A1 31, which are required for the commands we’ll be sending.

Step 2: Putting the RKE into Programming Mode

Now we will send the command to put the RKE system into programming mode. In your terminal software, type the following command and press “Enter”:

00 00 00

This sends the command 24 A1 31 00 00 00 (the header bytes are automatically prepended by the ELM327). If successful, you should receive the response: 26 A1 71 00 00 00. This confirms that your Jeep has entered programming mode.

Step 3: Specifying the Memory Slot

Next, we need to tell the RKE system which memory slot to assign to the new key fob. Key fobs are stored in memory slots 1 through 4. If you are programming your first key fob or want to overwrite the first slot, use 01. For the second key fob, use 02, and so on. In your terminal software, type the following command, replacing XX with the desired memory slot number (e.g., 01, 02, 03, or 04) and press “Enter”:

XX 00 00

For example, to program the key fob to memory slot 1, you would type 01 00 00. A successful response will be: 26 A1 71 XX 00 00, where XX matches the memory slot you selected.

Step 4: Programming the Key Fob

Immediately after sending the command in Step 3 and receiving the successful response, take your 2004 Jeep Cherokee key fob and press and hold either the “Lock” or “Unlock” button. Continue holding the button until you hear the door lock relays activate. This usually happens within a few seconds. The activation of the door locks confirms that the key fob has been successfully programmed to the selected memory slot.

Step 5: Programming Additional Key Fobs (If Needed)

If you need to program additional key fobs, repeat Steps 2 through 4 for each key fob, incrementing the memory slot number (XX) in Step 3 for each new key fob. You can program up to four key fobs. Remember that memory slot 1 is often assigned to the original key fob (if one exists). You can program new key fobs to slots 2, 3, and 4, or overwrite any existing slot.

Step 6: Finalizing the Programming

Once you have programmed all desired key fobs, turn the ignition switch to the “OFF” position. This will terminate the programming mode and finalize the process.

Important Considerations and Disclaimer

This DIY method provides a way to program your 2004 Jeep Cherokee key fob without requiring dealer tools. It has been successfully tested on a 2004 Jeep Grand Cherokee WJ and is likely to work on other 1999-2004 models.

However, please be aware of the following:

• Proceed with Caution: Interfacing with your vehicle’s OBD2 port involves sending commands to its computer system. While this procedure has been tested without harm, there is always a potential risk. Perform this procedure at your own risk.
• Compatibility: While likely compatible with 1999-2004 Jeep Grand Cherokee WJ models, verify compatibility for your specific Jeep model and year.
• ELM327 Interface Quality: The success of this method depends on the quality and proper functioning of your ELM327 OBD2 interface. Ensure you are using a reliable device.

By following these steps carefully, you can potentially program your 2004 Jeep Cherokee key fob yourself and regain the convenience of remote keyless entry without a trip to the dealership. Remember to always double-check compatibility and proceed with caution when working with your vehicle’s electronic systems.