Author Topic: So clueless, I don't even know what to search for ~ programming 93c56 eeprom  (Read 195 times)

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Offline v4mofo

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I'm ignorant.  Simply have nearly zero frame of reference upon which to draw, but I'd like to learn.  Any help, any at all, would be appreciated (including links to the dreadfully basic stuff I'm going to have no clue about).

Anyway, my project is to "virgin" immobilizer key data on a newly purchased 1999 Toyota 4runner.  In Toyotas infinite wisdom, they made the 1999 and 2000 (and probably other cars in that time) not be programmable through the OBDII and/or their software.  2001, they figured it out and changed their ways.  According to them, the only way a person can get new keys (should all the keys be lost or the body control computer be damaged) is if they spend the ~$1000 to buy one.  Locksmiths have figured it out though, but at $500 I see a lot of potential to learn something myself, which I enjoy.  I've found some data on doing this process myself, seems to be well within my ability except for the gaping hole of information about the Hardware needed for programming. 

Incase you're worried about the legality of this, I'm *MORE* than willing to verify myself to any admin/moderator of the site.  Just say the word.

The chip I need to read/modify/write to is a 93C56 8-leg EEPROM (lol, I feel like a kid trying to talk about retirement planning with 60y/os).  There don't seem to be many Chinesium ready-made options, the 2 that come up are a CH341A usb based board, but it seems to be more for the 24xx/25xx chips with some listings also including 93xx and I don't know if they would actually work.  And a EP2010, but the only info I can find on that is a video showing it making a copy, which isn't useful to me. 

Then there are schematics.  I'm good with wiring diagrams (background in motorcycle mechanics, and I really enjoyed electrical troubleshooting no one else could figure out), but circuit schematics are beyond me.  The "easiest" one (claimed) is attached in pdf that I found over here: (pdf link is dead in that link, had to grab it from  And the jpg attachment seems to be the easiest single-use schematic I've seen.   There are plenty of other more complex offerings out there, but they all do more things.  And to add yet more complication to this mess, I've not had a computer with an Actual serial port for well over 10 years and probably close to 15, I do have a usb->serial adapter (Keyspan USA-19hs) that's worked well for the 2 legacy items I've needed it for but I don't know if it'll work here.

So, all that randomness spewed out ( :blah: ), might I get some advice on a more logical approach and what I need to understand first?  I know I'm all over the map here with unknown variables, let me try putting it this way:

What's the most efficient, least costly way for me to read and write data to a 93C56.  Maybe I'm over-complicating this.

Doing this on the personal level (once, or at least one chip unless I mess up), with the double goal of learning something new and accomplishing my end goal (functional keys for a $2k vehicle).

Thanks for absolutely Any advice you might offer.  Seriously. 

Offline mikerj

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  • Country: gb
If you don't mind Chinesium stuff, the EZP2010 programmers are inexpensive and will handle a wide range of I2C (24xx) and SPI (93xx) EEPROMs.

Bit bashing serial ports for this kind of thing is often an exercise in frustration.

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