When you replace your 2001, 2002 or 2003 Toyota RAV4 ECM (car computer or engine computer) with an used unit, either bought at eBay or at a salvage yard, junker, etc., if your vehicle is equipped with an immobilizer system, which is an anti-theft security system, you must either reprogram the ecm to work with your existing keys, or buy new keys, which must be cut and programmed for matching the ECM unit you just purchased.
In this article, we will cover the part where the ECM is reprogrammed, as that is the easier way, and will use as an example the 89661-42820 RAV4 ECM. That part number is to mention just one, as this procedure will cover all 2001 – 2003 models, either 4×2 or 4×4 wheel drive.
For reprogramming, if you have an EEPROM programmer, you can do the programming either in circuit or off circuit by using a reset file for the immobilizer EEPROM in the ECM circuit. If you have such a programmer, you may get the immobilizer reset file for download at: 2001-2003 Toyota Immobilizer Reset file Download, and may see the following article if you which to do the programming “in-circuit”: Reading and Writing Immobilizer EEPROMs in circuit. Otherwise, you will need to remove the EEPROM, reprogram it and resolder it back in the circuit.
If you DO NOT have an EEPROM programmer, but have some soldering skills on electronic circuits, then keep on reading, as the following procedure will help you do the job without investing in a programmer.
You will first need to get a “Immobilizer Reset EEPROM“. What to do with that or what is it for? Well, first of all, an Immobilizer Reset EEPROM is an EEPROM (in this case a 25080 SPI EEPROM) already programmed with an immobilizer reset software, which after installed in the ECM circuit, it will put the ECM in auto-register mode. that means that after installing the ECM back in the vehicle, it will register the first key you use on it. Of course, that first key will be your existing key. After that, the other keys you have will also work. For the “what to do with that” question, you will just replace the EEPROM that is in the circuit of the ECM you bought, with this reset EEPROM. Your replacement ECM will be in auto-register mode, as explained above. In that mode, you just put your existing key in the key lock cylinder, wait for 10 seconds and it is ready to use. The ECM will be locked to your keys and will ONLY work with them, the same as buying a brand new ECM.
For this job, you will need to unsolder the existing EEPROM inside the ECM and solder the reset EEPROM in its place. The existing EEPROM will have the markings “25080” on it and it is located near one of the micro controllers (big black squares), with the reference “IC1003” on the circuit board. Below is a picture of the ECM’s circuit and some details for easily locating the parts.
In the picture above, you can see the location of the immobilizer EEPROM. Take note of the orientation of Pin#1, as the reset EEPROM must be installed the same way. For replacing the EEPROM, just unsolder the existing one and solder the reset EEPROM in. You may be thinking at this time; “But wait! That it is an SMD (Surface Mounted Device) chip! and my soldering skills are limited to “through hole” parts. Well, it is an SMD chip, but it is very easy job if you are able to do regular soldering on circuit boards. Check the pictures below on how to do it.
That’s it! After soldering all the 8 pins of the EEPROM chip, make sure that; again, pin #1 is pointing to the right direction, make sure that there is no soldering debris on any part of the circuit and make sure that you put the new (Reset) EEPROM and did not install back the same EEPROM you just took out without noticing
Now is time to put your ECM back together and reinstall it in your RAV4. Put your key in the cylinder lock without turning it to any direction, wait 10 seconds and then start the engine. If everything was done right, it will start and run as normal.