The last one or two bytes of each 16 byte page is the checksum, and it is literally just the sum of the bytes in the page. You should just be able to manually correct them.

Sorry to bother you a little more, my somewhat limited and feared exposure to hex, is there a simpler way to calc the sum of the hex values?

I've converted them to decimal, added, then tried to convert back to hex and all I'm getting back is simply garbage.

It's a little more complicated in that. I am still working out the specifics, so please correct me if someone knows better..

Not all regions have checksums. Page 0 (0x00 - 0x0F)?

The checksums for pages 1 to 14 appear to calculate as follows..

FFFF - ((Chksum-16 of first 14 bytes)+(page number-1)) then swap the Hi and Lo byte

So for my page 1 (0x10-0x1F)
05 01 02 00 1E CF 01 00 03 00 5A 8E 00 D2 4C FD
Checksum16 of [05 01 02 00 1E CF 01 00 03 00 5A 8E 00 D2] = 02B3

FFFF - ((02B3) + (1-1)) = FD4C The checksum is 4C FD

For my page 2 the data is repeated so the checksum is

FFFF - ((02B3) + (2-1)) = FD4B The checksum is 4B FD

This covers the first portion of the EEPROM but I haven't looked further to see which regions are covered. With a good dump it should be simple to work it out.

-C

Nice work. May I ask from which part of the object code you got this info from?

I'm not sure the page info table is constant across car models & ecm versions.

I've played around a bit and made a small perl script for verification. It doesn't use the weird method the ME7 uses, it simply compares against an array with offsets from (0xFFFF-<sum>). Only the first 16 pages are checked. It also prints soft coding and speed governor offset.

I think the info you need is already in the previous posts above.

You need to locate e.g. the following function in your image, then you know the address of
the eeprom_info_table and can check wether there exist different versions:
; INPUT:
;   R12 = ptrBuffer
;   R13 = pageNumber (0..31)
; OUTPUT:
;   R4 = 0 (checksum is OK), != 0 (checksum is wrong)
verify_eeprom_checksum_from_buffer:
        MOV     [-R0], R9
        MOV     R4, R13                 ; Get pageNumber
        SHL     R4, #1
        MOV     R5, [R4+#eeprom_info_table]   ; val = eeprom_info_table[pageNumber]
        AND     R5, #0040h
        SHR     R5, #6                  ; cksumBit = (val & 40) >> 6
        MOV     R15, R13                ; Get pageNumber
        SUB     R15, R5                 ; baseCksum = pageNumber - cksumBit
        MOV     R4, #14
        MOV     R14, R4                 ; len = 14
        MOV     R5, R12                 ; Get ptrBuffer
        ADD     R5, R4                  ; ptrLast = ptrBuffer + len
        MOV     R9, [R5]                ; checksum = *ptrLast (old checksum)
        JMPR    cc_UC, L_enter_loop
L_loop:
        SUB     R14, #1                 ; len--
        MOV     R4, R14                 ; Get len
        MOV     R2, R12                 ; Get ptrBuffer
        ADD     R2, R4
        MOVB    RL4, [R2]               ; data = *ptrBuffer + len
        MOVBZ   R4, RL4
        ADD     R9, R4                  ; checksum += data
L_enter_loop:
        CMP     R14, #0
        JMPR    cc_SGT, L_loop          ; (len > 0) ?
        MOV     R4, R9
        ADD     R4, R15                 ; Return checksum + baseCksum
        MOV     R9, [R0+]
        RETS

Were you able to get the file to write?   Try holding the write protect high.