DIY: Program Your 2004 Jeep Grand Cherokee Key Fob Without Dealer Tools

Lost your key fob or need an extra one for your 2004 Jeep Grand Cherokee? Going to the dealership for a replacement and programming can be costly and inconvenient. While official procedures might suggest dealer intervention for models like the 2004 Jeep Grand Cherokee (WJ body code), there’s a way to program your key fob yourself using readily available, affordable tools. This guide will walk you through a method that allows you to program your 04 Jeep Grand Cherokee Key Fob at home, saving you time and money.

This method leverages the OBD2 port in your Jeep and a simple ELM327 interface, along with terminal software on your computer. Don’t worry, you don’t need to be a computer expert to follow these steps. This approach was successfully tested on a 2004 Jeep Grand Cherokee WJ and is likely to work for models from 1999 to 2004.

Understanding Your Jeep’s Key Fob System

Your Jeep Grand Cherokee’s Remote Keyless Entry (RKE) system is managed by the Passenger Door Module (PDM). The PDM has memory for up to four key fobs. By sending specific commands through the OBD2 port, we can put the RKE system into programming mode and assign a memory slot for each new key fob.

What You’ll Need:

• An ELM327 based OBD2 interface (easily found online)
• A computer with RS232 terminal software (like PuTTY or Tera Term)
• Your new 04 Jeep Grand Cherokee key fob

Step-by-Step Guide to Programming Your Key Fob:

Before you begin, ensure your ignition key is in the “ON” position, but the engine is NOT running (KOEO – Key On Engine Off).

1. Setting up the ELM327 Interface:

   You’ll need to use your RS232 terminal software to communicate with the ELM327 interface and configure it. Enter the following commands one by one, pressing “Enter” after each:

   • AT L1 (Turns line feeds on for better readability)
   • AT H1 (Turns headers on, which are needed for the commands)
   • AT E1 (Turns echo on, so you can see what you are typing)
   • AT SP2 (Sets the communication protocol to VPW, which is used by your Jeep)
   • AT RA A1 (Sets the receive address to A1 to view responses from the PDM)
   • AT SH 24 A1 31 (Sets the header bytes for the commands we will send)

2. Entering Programming Mode (Step 1 Command):

   Now, send the command to put the RKE system into programming mode. In your terminal software, type:

   • 00 00 00

   This corresponds to the HEX command 24 A1 31 00 00 00. The ELM327 automatically adds the header bytes we set up in the previous step.

   If successful, you should receive the following response from your Jeep:

   • 26 A1 71 00 00 00

   This response confirms that your Jeep’s RKE is now in programming mode.

3. Specifying Memory Slot (Step 2 Command):

   Next, you need to tell the system which memory slot to use for the new key fob. You can choose slots 01, 02, 03, or 04. For the first key fob, you would typically use slot 01. For the second, slot 02, and so on.

   To assign memory slot 01, type:

   • 01 00 00

   This corresponds to the HEX command 24 A1 31 01 00 00 (where “01” represents the memory slot XX). If you want to use slot 02, you would type 02 00 00, and so on.

   A successful response will look like this (with XX matching the slot you chose):

   • 26 A1 71 XX 00 00

4. Programming the Key Fob (Step 3):

   Now, take your 04 Jeep Grand Cherokee key fob and press and hold either the “Lock” or “Unlock” button. Keep holding the button down until you hear the door lock relays activate. This usually happens within a few seconds. The sound of the door locks clicking confirms that the key fob has been successfully programmed to the chosen memory slot.

5. Programming Additional Key Fobs:

   If you need to program more key fobs, repeat steps 2 through 4 for each additional fob, incrementing the memory slot number (XX) each time. For example, for a third key fob, you would use memory slot 03.

6. Exiting Programming Mode:

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

Important Considerations:

• Memory Slots: Memory slot 01 is often assigned to the original key fob. If you still have a working key fob, it’s likely in slot 01. You can program new key fobs to slots 02, 03, or 04. Alternatively, you can reprogram any slot, overwriting any previously programmed key fob in that slot. The slot numbers don’t need to be sequential.
• Safety and Risk: Interfacing with your vehicle’s OBD2 port carries inherent risks. While this procedure has been tested successfully without causing harm, proceed with caution and at your own risk. The developers of this method are not responsible for any damage that may occur.

Conclusion:

Programming your 04 Jeep Grand Cherokee key fob doesn’t have to be a dealer-exclusive task. By using an ELM327 interface and following these steps, you can easily add or replace key fobs yourself. This DIY method offers a cost-effective and convenient solution for managing your vehicle’s keyless entry system. Remember to always exercise caution when working with your vehicle’s electronics.