E39A Vin write by DID

[Archimedes]

Hi I am new to the forum and fairly new to working with GM ecu's. I am writing to ask some help in writing vin to ecm. I have gained security access and can read current vin but when i try to write vin it doesn't change. Here are my messages sent and recieved.

Request Ecu Seed by obd
Sent : 7E0 08 02 27 01 AA AA AA AA AA
RECV : 7E8 08 04 67 01 17 03 AA AA AA
Sent : 7E0 08 04 27 02 C6 B5 AA AA AA
Message Recieved seed is 0x1703 Sent key 0xC6B5
RECV : 7E8 08 02 67 02 AA AA AA AA AA
Message Recieved OK! Key is good!

Request Ecu Upload
Sent : 7E0 08 13 3B 90 31 37 4B 4B 52
RECV : 7E8 03 30 00 0A 5A 00 00 00 00
Sent : 7E0 08 21 52 50 4B 44 31 44 4A
Sent : 7E0 08 22 4A 32 32 33 33 37 37

Request VIN by obd
Sent : 7E0 08 02 09 02 AA AA AA AA AA
RECV : 7E8 08 10 14 49 02 01 31 47 4B
Sent : 7E0 08 30 00 00 00 00 00 00 00
RECV : 7E8 08 21 4B 52 50 4B 44 31 44
RECV : 7E8 08 22 4A 32 32 33 33 30 35
Message Recieved : 1GKKRPKD1DJ223305

Can somebody help with what I am missing?

[ironduke]

What is the reply to the vin write commands below?

Sent : 7E0 08 13 3B 90 31 37 4B 4B 52
RECV : 7E8 03 30 00 0A 5A 00 00 00 00
Sent : 7E0 08 21 52 50 4B 44 31 44 4A
Sent : 7E0 08 22 4A 32 32 33 33 37 37
There should be a 7E8 reply here.. Curious what it is..

2 things come to mind, you need to turn the key off after writing if the write reply was a good one, secondly sometimes you need to send a clear code command prior to unlocking and vin writing.

[Archimedes]

So this is what i get in response sorry i must have missed it last time.

Request Ecu Seed by obd
Sent : 7E0 08 02 27 01 AA AA AA AA AA
RECV : 7E8 08 04 67 01 17 03 AA AA AA
Sent : 7E0 08 04 27 02 C6 B5 AA AA AA
Message Recieved seed is 0x1703 Sent key 0xC6B5!
RECV : 7E8 08 02 67 02 AA AA AA AA AA
Message Recieved OK! Key is 0x0001 good!

Request Ecu Upload!
Sent : 7E0 08 13 3B 90 31 37 4B 4B 52
RECV : 7E8 03 30 00 0A 5A 00 00 00 00
Sent : 7E0 08 21 52 50 4B 44 31 44 4A
Sent : 7E0 08 22 4A 32 32 33 33 37 37
RECV : 7E8 08 01 60 AA AA AA AA AA AA

Request VIN by obd
Sent : 7E0 08 02 09 02 AA AA AA AA AA
RECV : 7E8 08 10 14 49 02 01 31 47 4B
Sent : 7E0 08 30 00 00 00 00 00 00 00
RECV : 7E8 08 21 4B 52 50 4B 44 31 44
RECV : 7E8 08 22 4A 32 32 33 33 30 35
Message Recieved : 1GKKRPKD1DJ223305

And obviously just for testing im trying to change the last 2 digits to 77 instead of 05

Thanks

[ironduke]

Are you doing this with a program? or typing it into a serial terminal?
I am guessing that your using a serial terminal and just getting the lines sent too slow?

You should be seeing 7E8 02 7B 90 as a good response from the 3B 90 vin write command. Your not even getting the 03 7F 12 failure reply so something is wrong, I'm guessing it's timing out.

[Archimedes]

I am using an arduino script i wrote with a esp32 and a tja1050 can transciever. I may be sending the data frames to slow after recieving the flow control frame?? How fast do you typically need to send in the data frames and then wait for the response?

[Archimedes]

Request Ecu Upload!
Sent : 7E0 08 12 3B 90 0A 47 4B 4B 52
RECV : 7E8 03 30 00 0A 00 00 00 1F 51
Sent : 7E0 08 21 50 4B 44 31 44 4A 32
Sent : 7E0 08 22 32 33 33 37 37 AA AA
Sent : 7E0 08 23 37 AA AA AA AA AA AA
Sent : 7E0 08 04 AA AA AA AA AA AA AA
RECV : 7E8 08 03 7F AA 12 AA AA AA AA

If I do this i do infact get a 7F error....

[ironduke]

Request Ecu Upload!
Sent : 7E0 08 12 3B 90 0A 47 4B 4B 52
RECV : 7E8 03 30 00 0A 00 00 00 1F 51
Sent : 7E0 08 21 50 4B 44 31 44 4A 32
Sent : 7E0 08 22 32 33 33 37 37 AA AA
Sent : 7E0 08 23 37 AA AA AA AA AA AA
Sent : 7E0 08 04 AA AA AA AA AA AA AA
RECV : 7E8 08 03 7F AA 12 AA AA AA AA

If I do this i do infact get a 7F error....

Command is different from previous. You are sending 0x13(19 bytes) bytes so that should be 13, not 12.. Shouldn't be sending a clear code command AFTER writing the vin but before you even unlock it. Sometimes not needed but I send it by default.
Not sure what the 08 is right after 7E0 or 7E8 on each line??? If your sending CAN RAW then that is a length byte but can't send more than 7 last I knew so it should error out but it's not refusing the command? Maybe something in your code is adding that for your benefit for some reason?

before unlocking
7E0 01 04 // clear code command


7E0 10 13 3B 90 47 4B 4B 52
7E830000A
7E0 21 50 4B 44 31 44 4A 32
7E0 22 32 33 33 37 37 37 00
7E8 02 7B 90 AAAAAAAAAA

[Archimedes]

Yeah the 08 is the can dlc length byte i was under the understanding that was always to be 8 as always the packets are 8 bytes long when the are sent on the bus. I will go threw my code again and try the clear code command before i unlock the ecu and see if that makes the difference. Ive read that some E39A ecu's dont allow the vin to be re-written?? Have you heard of that?

[ironduke]

I've been able to write the vins on anything I believe.. There is a security code/pin/immo that is to be dealt with as well.. If your trying to install a used ecm that'll be an issue.

your not sending the 08, are you??

[Archimedes]

Hi i believe the 08 is sent by default with every packet automatically? I will have to read the docs on the esp32 can library.