All Keys Lost EEPROM 90s/Early 200s Lexus/Toyota Program Under $25 Writeup!

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notdylanlol

notdylanlol

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Jan 26, 2025
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Hey guys, after fighting with this process myself for hours on end, after getting it to work I figured I would make a writeup on how to do this.

Here's how to reprogram your car's engine immobilizer to program new keys in the event of lost keys or a swapped ECU.

I recently bought a 2001 LX470 from a junkyard with no keys and researched many options. I found the most popular way to virginize the IC900 EEPROM 93C56 chip on the ECU. I ordered the CH341a reader set from Ebay for about $18 and so it started. It did not work at first as many things don’t. That was followed by well over 30 hours of research and testing and only finding this method to work.

I will supply a link and download to writeup!

Writeup
 

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That is impressive work. Way beyond my skills but impressive nonetheless.
 
Thank you so much! This was a lifesaver since my car came with only the valet key. Got 2 more keys from ebay pre cut with a picture and programmed it. I didn't desolder the chip from the ECU since I didn't have a hot air station. I cleaned the pads a lil bit with a screw driver and threw the clip onto the EEPROM, took a few tries to get it reading right.

On my 2000, the first key registered fine, but the security light didn't blink. After I did all three keys, I inserted one of the supposed master keys again, but it made my remote key a valet. So it didn't read one of the first two keys as a valet, odd.
 
Hey! I have a 2001 ES300 that I purchased another identical ECU for. My techstream software doesn't have the option to setup the new ecu and immobilizer to get my original key working. Could I use the IC900 that is in the original ECU, pull it from the board, then replace the IC900 on the new ECU with it? I know it's different circumstances, but figured i'd ask to see if it could be that simple for my situation?
 
I have a 2004 LX that came with one valet key and I’m fighting with Techstream to reset the immobilizer so I can finally have a working master. Any idea if the EEPROM reset works for 2004-2007?
 
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