2006 pontiac grand prix bcm

[geep]

I went playing with gpt 5 and a OBDX pro gt and i think it managed to pull most of the bcm .bin file figure i would put it here for others to look at and critique not a coder by any means so don't be to hard on me lol

[ProfessWRX]

What did you do to get it?

I’ve wanted access to my bcm for a while. Don’t know how hard reverse engineering it will be without documentation tho.

[geep]

The hard part was figuring out the cpu family mine turned out to be real close to a MC68HC912DG128 if not the actual chip itself. The numbers on the chip in the bcm were SC511337VPV — 3K92D — 00CX0511 after i found the .pdf for the MC68HC912DG128 it went pretty quick. I went back and forth for a while with gpt generating power shell scripts me asking it silly questions along the way like why do i need a chip test clip /prog seek /bdm/ others. It really wanted to go that way for some reason. Then i told it that is not how gm updates them and it was like a light came on .Here try this script and we were in pretty silly really. I think i have some of the scrips saved if people want look at those.

[geep]

A few picture because i couldn't find any of the insides. The pick of the chip that looks a eprom its not its a power chip of some type the eprom is in the cpu

[ProfessWRX]

Very cool. Yes please share any and all details you can.

[geep]

The .rar has .bat and read-me its a slow read but could probably be optimized to read faster. I am not a coder. I only started playing with bcm because i can be driving down the road and everything shuts off except the engine and it is really random i figure the 22 year old bcm / capacitors are on the way out.

[geep]

Does any one have knowledge of how to flash them back. I have gotten past the first seed key challenge. I went back and forth for awhile with claud and gpt they keep talking about a trap when writing. If you write to the wrong trapped address it will reset via cop. I haven't tried writing yet. I think cop is what is happening when i am driving down the road. It just resets randomly i have read through the colarado bcm thread kinda seems like maybe the trap is what's going on there write two one place and it moves

[antus]

cop is a failsafe where it expects to see a certain software sequence every so often, the idea is if the BCM software crashes eg gets stuck in a loop, then the event won't happen that the COP is waiting for, and it triggers a reset so that the module will start working again. Under normal operation it does not happen. But when you are writing your own programming software to run on the chip, then your software needs to be aware of the COP and satisfy the sequence every so often to avoid the reset. It is also called a watchdog, and it is typical for the ECMs/PCMs and vehicle modules. It won't be triggering on yours under normal operation unless there is a genuine fault. Trap is also not the same as a literal trap that is set for you. It is more like an interrupt. The CPU has a number of traps and when you program it you can connect a trap to a software function to do a certain thing, for example service communications hardware. In that regard it is similar to an IRQ. It won't move around on it's own when triggered. If you are writing your own programming software you can probably ignore traps. https://stackoverflow.com/questions/777 ... -is-a-trap

[kur4o]

The bcm might be one time program in factory[ROM], and changing tune is not possible, however some of the option values in eeprom can be overwritten, using tech2 if mec is >0, usually a blanked new bcm can accept these on initial configuration.

Looked at script and it just use inbuilt mode23 to dump the content to a file. Ask AI to make a disassembly of the file, and figure supported modes and trace some of the option logic.

[geep]

6. The "Enable Programming Mode" dispatcher — found and verified
In the '04 firmware, a real, verified-reachable service-ID dispatcher was
located at `$8EBE` onward:
```
8EC0: CMPA #$A5 ; requested service == $A5 (Enable Programming Mode)?
8EC2: BNE $8ECF
8EC8: CALL $A360, page $02
8ECC: JMP $8F70

8ED1: CMPA #$A4 ; next service...
8ED9: CALL $A3A9, page $02
8EE2: CMPA #$A8 ; ...and so on
```
`$A360` (page 2, which happened to be the page captured in this dump) was
disassembled directly. It performs:
RAM bookkeeping (stashing an incoming parameter)
A bounds-check against the constant `$0132` (306 decimal), setting/
clearing a flag byte based on the result
A running `ADCA`/`ADCB` add-with-carry chain — a checksum or size
accumulation
Two further paged calls, to `$AE58` (page `$00`) and `$8000` (page `$05`)
This is consistent with session/parameter negotiation for entering
programming mode (block-size validation, checksum setup) — not the
flash-write algorithm itself, which matches finding #5 above. The two
follow-on calls could not be traced further: they target physical pages 0
and 5, which aren't present in this single-page-2 snapshot. (What's
sitting at those file offsets right now is unrelated page-2 content,
already checked and confirmed not to be the real target.)
To go further on this thread: additional dumps of the same unit with
`PPAGE` forced to `0` and `5` before reading `$8000–$BFFF` each time would
be needed to see the real continuation.