[Gmecm] Need ecu file for 1227303 ecm & checksum question

[Jay Vessels]

Hi there!

I'm not sure about the program gmcks, but it sounds like it doesn't know 
the checksum location for that MEMCAL.  GM placed it in different places 
for different codebases, so your checksum may just be calculated in a 
place that is different from what your program expects.  GM's method for 
calculating the checksum didn't seem to change over the years (at least, 
pre-OBD-II) so you could probably play around with the checksum location 
and figure it out.

Jay Vessels
1982 Chevrolet S-10 Sport, 2.8V6 TBI
1984 Chevrolet S-10 Blazer Sport, 2.8V6 (TBI pending)

James Ortiz wrote:
> Hi, 
>  I have a 1988 Pontiac Le Mans 1.6L 4 Cly 5 spd man transmission with a
> 1227303 ecm. I wanted to change a few things so i pulled the memcal
> (ANAB 1727) hooked it to my programmer and read the chip. Ran the gmcks
> program on it and it says the checksum does NOT match calculated sum.
> Put the memcal back in the programmer and checked all the connections
> with a meter to verify good contact. Read it again and compared it to
> the first read and they were the same. Did a partial disassembly and
> checked the code at the start vector and it looks like valid code. I
> have not had the time to do a full disassembly.
> 
> Concerned that i might have somehow damaged the memcal i put it back in
> the car to check it out. The car seems to be running fine. No check
> engine light. Jumped the aldl connector and all i get is code 12.
> Location 0008 in the bin is $53 NOT $AA so i don't think the checksum
> is being bypassed.
> 
> Is it possible that there is a different checksum routine used with
> this ecm or do i just have a bad read?
> 
> I have not been able to find a bin or ecu file from a 1227303 to
> compare.
> 
> Anyone have any ideas?
> 
> James