2003 Jeep Grand Cherokee Key Fob Programming: A DIY Guide

Is your 2003 Jeep Grand Cherokee key fob malfunctioning, or did you get a new one that needs programming? You might think a trip to the dealership is inevitable, but you could be wrong. While official procedures often suggest dealer-level tools, this guide reveals a method to program your key fob yourself using readily available equipment. This approach, successfully tested on a 2004 model and likely applicable to 1999-2004 Jeep Grand Cherokee WJs, leverages the OBD2 port and a simple interface.

Understanding the Original Dealer Method

Official documentation, like the “Daimler Chrysler North American Remote Keyless Entry Programming Procedure” (RKE 81-170-00011), outlines several key fob programming methods. For Jeep vehicles from 1999 to 2002, methods A through C are relevant. Methods A and B are customer-programmable procedures often found online. However, Method C is designated as a dealer programming method, typically requiring a DRB III scan tool. Crucially, documentation indicates that Jeep Grand Cherokee WJ models necessitate this Method C.

DIY Key Fob Programming for 2003 Jeep Grand Cherokee via OBD2

Despite the official stance, a dealer-free method exists for 2003 Jeep Grand Cherokees and similar models. This technique bypasses the need for specialized scan tools and instead utilizes an ELM327 based OBD2 interface and RS232 terminal software. This approach directly communicates with the vehicle’s Passenger Door Module (PDM), which manages the Remote Keyless Entry (RKE) system. The PDM has four memory slots, allowing you to program up to four key fobs. By sending specific commands through the OBD2 port, you can put the RKE into programming mode and assign memory slots to your key fobs.

What You’ll Need

To perform this DIY programming, you will need the following:

• ELM327 based OBD2 interface: This device acts as a bridge between your computer and your vehicle’s OBD2 port. These interfaces are widely available online.
• RS232 terminal software: This software allows your computer to communicate with the ELM327 interface. Popular options include PuTTY or Tera Term.
• A computer with an RS232 port or a USB to RS232 adapter: This is needed to connect your computer to the ELM327 interface.
• Your 2003 Jeep Grand Cherokee key fob(s): Ensure you have the key fobs you wish to program.

Step-by-Step Programming Instructions

Follow these steps carefully to program your 2003 Jeep Grand Cherokee key fob:

1. Establish Connection:

   • Connect the ELM327 interface to your Jeep’s OBD2 port (usually located under the dashboard on the driver’s side).
   • Connect the ELM327 interface to your computer using the RS232 cable or adapter.
   • Open your RS232 terminal software and configure it to connect to the COM port associated with your ELM327 interface.

2. Initialize ELM327:

   • Once connected, you need to initialize the ELM327 interface by sending the following commands one by one, pressing Enter after each:

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

     • AT L1 (Line feeds on)
     • AT H1 (Headers on)
     • AT E1 (Echo on)
     • AT SP2 (Sets communication protocol to VPW – Variable Pulse Width Modulation, common for Chrysler vehicles)
     • AT RA A1 (Sets receive address to A1 for viewing vehicle responses from the PDM)
     • AT SH 24 A1 31 (Sets the header bytes for the commands we will send)

3. Enter Programming Mode (Step 1 Command):

   • Turn your Jeep Grand Cherokee’s ignition key to the “ON” position, but do not start the engine (KOEO – Key On, Engine Off).
   • Send the following command in your terminal software to put the RKE into programming mode:

     00 00 00

   • You should receive a successful vehicle response: 26 A1 71 00 00 00. This confirms the vehicle is in programming mode.

4. Specify Memory Slot (Step 2 Command):

   • Now, specify the memory slot for the key fob you are programming. Memory slots are numbered 01, 02, 03, and 04. For the first key fob, use 01. For the second, use 02, and so on.
   • Send the following command, replacing XX with the desired memory slot number (e.g., 01, 02, 03, or 04):

     XX 00 00

     • For example, to program the key fob to memory slot 1, send: 01 00 00
   • You should receive a successful vehicle response: 26 A1 71 XX 00 00, where XX corresponds to the memory slot you specified.

5. Program Key Fob (Step 3):

   • Immediately after sending the memory slot command, press and hold the “Lock” or “Unlock” button on the key fob you are programming.
   • Continue holding the button until you hear the door lock relays activate. This usually happens within a few seconds. This confirms the key fob is programmed to the specified memory slot.

6. Repeat for Additional Key Fobs:

   • If you have more key fobs to program, repeat steps 3 through 5, incrementing the memory slot number (XX) for each subsequent key fob.

7. Exit Programming Mode:

   • Once you have programmed all desired key fobs, turn the ignition key to the “OFF” position. This terminates the programming mode.

Important Considerations and Tips

• Existing Key Fobs: If you already have a working key fob, it’s likely assigned to memory slot 1. You can program new key fobs starting from slot 2. Alternatively, you can reprogram the existing key fob to memory slot 1 or any other slot.
• Memory Slot Order: Memory slot numbers do not need to be sequential, and any slot can be overwritten using this procedure.
• Caution: Interfacing with your vehicle’s OBD2 port carries inherent risks. Proceed with caution and at your own risk. However, this procedure has been tested and has not caused harm to the vehicle or related components in testing.

By following these steps, you can potentially save yourself a trip to the dealership and program your 2003 Jeep Grand Cherokee key fob yourself. This DIY method offers a cost-effective and convenient alternative to dealer programming.