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    #1

    93C46 and 93C56 EEPROM

    I tore apart my instrument cluster for my 2008 Toyota Corolla made in 2007 in Cambridge, Ontario, Canada and pcb location: IC6=EEPROM is a surface mounted device with part # of 93C46W7, some claim the EEPROM out of a Camry part # 93C56 will allow odometer to roll over 299 999 KM or miles. The data sheet for both is below:

    https://cdn.badcaps-static.com/pdfs/...c6e42b20d3.pdf 2

    Anyone know if the Camry one will work on my Corolla?. And which EEPROM reader/writers do you all recommend I purchase that will allow me to read the old values of the old EEPROM and program the new EEPROM from a Camry # 93C56 which I will purchase from Digi-Key?. Again both of these EEPROMs are surface mounted devices, not through hole. I am an electronics engineering technician by trade and have no problem soldering out the chip and soldering in a new one but software was always my weakness.

    For those of your not familiar with I am doing, for the North America market ALL:

    2003-2008 Toyota Corolla
    2003-2008 Toyota Matrix
    2003-2008 Pontiac Vibe
    2004-2005 Toyota Prius

    when the odometer reaches 299 999 KM or miles it stops, and will not roll over to 300 000 KM or miles but if you read the EEPROM it continues to count true mileage but display only shows 299 999. Summary: I would like to know if I purchase from Digi-key a 93C56 EEPROM to replace my Corolla 93C46 EEPROM if the odometer will roll to 300 000 KM or miles and continue to count. Also which EEPROM reader/programmer do you all recommend that allows to interface with a surface mounted device (not through hole).

    Thank you in advance for help/replies.

    Sidney
    Dartmouth, Nova Scotia
    Canada
    Tags: None
    #2
    Re: 93C46 and 93C56 EEPROM

    changing the eeprom will not work,
    the lack of rollover is down to the software in the dash or ecu

    it's possible there are configuration bytes in the eeprom that could help, but you would need to ask on a toyota hacking forum.

    Comment

      #3
      Re: 93C46 and 93C56 EEPROM

      Originally posted by stj View Post
      changing the eeprom will not work,
      the lack of rollover is down to the software in the dash or ecu

      it's possible there are configuration bytes in the eeprom that could help, but you would need to ask on a toyota hacking forum.
      There is a micro in the instrument cluster, this guy is confusing but it might help you to help me:

      https://socalspeedometer.com/speedom...m-or-miles-why

      Comment

        #4
        Re: 93C46 and 93C56 EEPROM

        no, he said what i said - it's a software issue.
        and looking at that picture, the miles/kilometers are encoded in some bullshit way to make it hard to change the readings.
        thats a seperate issue btw and easily fixed by just restoring an earlier backup

        Comment

          #5
          Re: 93C46 and 93C56 EEPROM

          This limitation was introduced because of to many people were rolling back mileage so they were forced to make very difficult to modify the odometer

          The only thing I could think might help you is to replace it with an odometer that has very low mileage and just make a note of the mileage when you did this so you keep track of how many miles are on this vehicle

          I have a truck that the odometer stopped working because of a stripped gear shaft I just found one in the junk yard that was not stripped and it been working for last few years now ( this was very difficult to do because you had to be careful not to strip the replacement parts or you would have to find another one that was not stripped )
          Last edited by sam_sam_sam; 06-14-2023, 07:32 PM.

          Comment

            #6
            Re: 93C46 and 93C56 EEPROM

            personally i think the whole idea of the odometer is bs,
            it does not tell you the condition of the drivetrain - thats down to how it was driven and serviced.
            look at ex-police stuff to see what i mean, they are usually very low mileage but beaten to hell!

            Porsche has the right idea, the newer cars track the engine runtime in hours - same as you would with an aircraft.

            Comment

              #7
              Re: 93C46 and 93C56 EEPROM

              Originally posted by sam_sam_sam View Post
              This limitation was introduced because of to many people were rolling back mileage so they were forced to make very difficult to modify the odometer

              The only thing I could think might help you is to replace it with an odometer that has very low mileage and just make a note of the mileage when you did this so you keep track of how many miles are on this vehicle

              I have a truck that the odometer stopped working because of a stripped gear shaft I just found one in the junk yard that was not stripped and it been working for last few years now ( this was very difficult to do because you had to be careful not to strip the replacement parts or you would have to find another one that was not stripped )
              But why do all other Toyota vehicles do not have that limitation?.

              Comment

                #8
                Re: 93C46 and 93C56 EEPROM

                The difference might be is if the odometer is digital instead of mechanical type of odometer that is shown as digital would be my guess

                Comment

                  #9
                  Re: 93C46 and 93C56 EEPROM

                  Originally posted by sam_sam_sam View Post
                  The difference might be is if the odometer is digital instead of mechanical type of odometer that is shown as digital would be my guess
                  What? they are all now digital.

                  Comment

                    #10
                    Re: 93C46 and 93C56 EEPROM

                    Originally posted by stj View Post
                    personally i think the whole idea of the odometer is bs,
                    it does not tell you the condition of the drivetrain - thats down to how it was driven and serviced.
                    look at ex-police stuff to see what i mean, they are usually very low mileage but beaten to hell!

                    Porsche has the right idea, the newer cars track the engine runtime in hours - same as you would with an aircraft.
                    There's a reason why runtime hours is used in aircraft, namely you can't tell distance traveled while in the air... so best proxy is hours. Then it could be said hours running shows nothing about the airframe stress quality, whether the airplane has been traveling through high winds, etc.

                    For cars, odometers do have a direct proxy over some parts, like transmissions and especially tires. They have a correlated but not direct effect to brake pads and of course engines.

                    YMMV. Of course.

                    ---

                    As an aside, odometers for electric cars is quite possibly a sham in this respect too, though it is still a weak proxy. Almost seems that quantity of full/partial/SOC-relative charge/discharge cycles should be the main metric to battery quality -- which is probably the number one wear item in electric cars.
                    Last edited by eccerr0r; 06-18-2023, 09:51 AM.

                    Comment

                      #11
                      Re: 93C46 and 93C56 EEPROM

                      odometer is often a legal requirement because of government documents that insist on it being noted.
                      anual inspection and ownership documents for example.
                      but with electric obviously the numbers arent worth shit and the real issue is going to be the battery charge-cycles.

                      Comment

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