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Topic starter
Good evening,
I recently purchased the torque pro app to help gain some additional understanding of the CAN bus and OBD2 protocols. A friend of mine has a 2009 Hyundai Accent. For kicks, I ran the PID scanner on it and found that multiple ECUs are replying. I'm trying to understand how the app was able to get 2 responses.
For example, the raw reply to 0x20:
$7e906412080018001
$7ef0641208007e011
Is this to indicate that 2 modules replied when the app sent just 1 command? Or, did the app make 2 requests; one with a header of 7e906 and one with a header of 7ef06? If the latter, how did it determine the appropriate header to send to each module? I did not see a PID available that I could query to "get module information". Is there such a thing that I'm just ignorant of? In the PID scanner output, column B for "Header" just says "Default" so I don't know what that means. Is there a "default" header I should be putting on subsequent requests?Using the ELM327 and some basic code, I manually made a request to 0x20, and I only received 1 response, and it did not have a header. Instead, it was just "41 20 80 01 80 01".
Hopefully someone can provide me a bit more guidance! Thanks in advance!
Posted : 18/03/2024 11:46 pm
Does this mean that 2 modules responded when the application only sent 1 command?
Yes, 2 ECUs, an engine block and an automatic transmission unit answered immediately
In the PID scanner output, column B for “Header” just says “Default”
try this for motor enter address 7E7 here
Posted : 19/03/2024 9:43 am
Greetings Cintakc.
It has been awhile for me
but wouldn't that be a 7E1
and 7E7 for the mode 01 pid 20 request.
ATSH may be useful in this case.
7E1
80 01 80 01
1000 0000 0000 0001
1000 0000 0000 0001
7E7
80 07 e0 11
1000 0000 0000 0111
1110 0000 0001 0001
Just curious if this
pid responds for both modules...
0121
Search Wiki for info on
OBD Pids.
Posted : 19/03/2024 12:10 pm
Topic starter
Thank you both for your replies. Is the header 7E7 and/or 7E1 a "standard" for requesting data specifically from the engine ECU?
In my example above, it looks like the 2 modules that are responding, one started with 7EF and the other with 7E9. I don't understand how the torque app was able to determine what headers to use in order to address these two modules individually.
Posted : 19/03/2024 1:52 pm
Search Wiki for OBD-II Pids.
Information is there that
should help.
Interesting reading for me
anyway.
Posted : 19/03/2024 7:22 pm
Topic starter
I have read them, but either I missed it, or there is no standard for headers. Do you know how to determine which modules are in a vehicle so that I might be able to individually address them?
Posted : 20/03/2024 12:58 am
possible options for EKUs addresses
engine: 7DF/7E8, 7E0/7E8, 7E7/7EF
AT: 7E1/7E9
for example (7E7/7EF)
7E7 - request address in the engine ECU
7EF - response address from the engine ECU
Posted : 20/03/2024 6:26 am
Topic starter
Okay great, thank you very much for that info. I'll make some adjustments and test!
Posted : 20/03/2024 3:56 pm
