Open source GM OBD2 flash tool using a ELM327 device
http://pcmhacking.net/forums/viewtopic.php?f=4&t=1566
Heres the HYPERTERMINAL setup, putty of course is the same. User beware this can be tricky also don’t bother messing with this unless you have your seed/key and are totally prepared to buy a new PCM. If your new to this I highly suggest you read ELM327DS
Baud 38400
parity none
Data bits 8
Stop Bits 1
Flow control none
Here’s the supposed procedure for a upload from the 411 PCM to a device (but it doesn’t work) any suggestions? Also not sure what PCMs this works on.
AT RV — CHECK VOLTAGE (MAKE SURE ITS 12 VOLTS. MULTIMETER AND CAL. IF NEEDED)
AT SP2 — SET ELM TO J1850
AT H1 — SET HEADERS ON
AT SH 6C FE F0 — SET HEADER
3F — TEST DEVICE PRESENT RX(NO DATA) why no data?
AT SH 6C F0 10 — SET HEADER TO
27 01 — GET SEED RX(6C F0 10 67 01 66 7E 52) your seed will be different
27 02 14 E7 — SEND CORRECT KEY RX(6C F0 10 67 02 34 4B) your key will be different
AT SH 6C FE F0 — SET HEADER
3F — TEST DEVICE PRESENT RX(NO DATA) why no data?
AT SH 6C F0 10 — SET HEADER TO
A1 — REQUEST HIGH SPEED MODE
You only have a short time before it returns to normal speed automatically <5 sec.
AT SH 6D 10 F1 –
36 00 00 80 FF 80 00 — (eg. 128 bytes, start loc FF8000)
after failure or success make sure to do this
AT SH 6C F0 10 — SET HEADER TO
A0 — RETURN TO NORMAL MODE
AT D — RESETS ELM
