I recently installed a refurbished ECM into a 2000 Lexus RX300. It has been programmed to the vehicle via the VIN. I’ve been told that the key immobilizer still needs to be programmed to the newly installed ECM.

With that said…

Can anybody recommend a software to download that I can use to program the key to these computers? Preferably a free software. 🙏🏼

 

You do not need any software or device to teach the ecu to accept another key. The only requirement is that you must have the MASTER KEY ... for the ECU that is installed. Armed with the MASTER Key you can program another key.

When you acquired the currently installed ECU did you get a registered Master Key with it? Use that and follow the procedure [please search here in a Club Lexus or on the net]
Do keep in mind that you will encounter 2 programming procedures related to the key
1. Immobilizer programming.
2. Key Fob programming for the key-fob buttons.

Use the right one for the right purpose. I would highly urge do one at a time and prevent aggravation and lost time/energy. Also if you do not understand the purpose of key-blade [groove cut], spend some time figuring that out. It may not be important now, but at the end it impacts the convenience. You can maybe return the ecu and get an another with Master Key and cylinders for all locks and ignition.

If you do not have the Master Key, You will have to resort to flashing EEProm on the ECU. [Hint contact member mouser privately or search the net for who can do this for you].

Check with auto-locksmiths as they can possibly provide this service. Be specific as to your model and year of RX. [Things have evolved, while the first gen did not allow reprogramming without a registered Master key].


Salim

PS: Imobilizer will prevent the generation of spark. You will be able to crank the engine with an unregistered key.
Further reading suggestion: Valet key ... if registered will allow the spark but can not be used to program/register another key.

 

Hey Salim. Thank you for the reply and thank you for the information.

When I received the refurbished ECM, it did NOT come with the registered master key. However, when I start the engine with the existing key, it has spark. 🤷🏻‍♂️

 

No point is arguing with success here. If the engine runs, you are only dealing with convenience issues.


That leaves only the KEYFOB programming:
Exercise extreme caution [[b]only follow the procedure to program the KEYFOB lock/unlock, window roll down, panic button].

Salim

PS: I would still urge that you process 2 keys, so make a copy or have one made again exercising caution that you do not destroy the working Master key. Also make sure you have a Master key and not a valet key.