I’m well versed in vpw now but still learning gm lan.
I’m observing a tech 2 and what to see what pid changes for clutch depressed, but there are several ones under transmission.
Are they still called mode AE pid requests?
Any literature on these pids?
E67 e38 gm lan pid info
Re: E67 e38 gm lan pid info
Live data is typically setup as DPIDs (Dynamic PIDs).
Basically theres some setup commands to tell the module which live data parameters to start broadcasting, and then the module will start spamming out the live data.
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Re: E67 e38 gm lan pid info
the DPID data the ecm broadcasts will be under the ID 0x5E8. the scan tool will request mode 0x2c to tell the ecm what pid to put in what buffer, and then I think mode 0xAA is the scan tool request to start the data broadcast. I can clarify more if it's needed. mode 0x22 is the request for the ecm to return the pid once, and the response ID will be 0x7E8
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Re: E67 e38 gm lan pid info
Tazzi wrote: ↑Wed Jan 03, 2024 8:33 pmLive data is typically setup as DPIDs (Dynamic PIDs).04colyZQ8 wrote: ↑Wed Jan 03, 2024 3:26 pm I’m well versed in vpw now but still learning gm lan.
I’m observing a tech 2 and what to see what pid changes for clutch depressed, but there are several ones under transmission.
Are they still called mode AE pid requests?
Thanks Tazzi I love your knowledge:)
Any literature on these pids?
Basically theres some setup commands to tell the module which live data parameters to start broadcasting, and then the module will start spamming out the live data.
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- Joined: Thu Jan 16, 2014 12:41 pm
- cars: 2004 Colorado 4.8L swap
86/90 Jimmy 6.5L diesel swap
80 Chevrolet Silverado TBI swap
88dodge W100 LPG conversion
Re: E67 e38 gm lan pid info
Thanks! Yes please help some more!!gmtech825 wrote: ↑Wed Jan 03, 2024 10:50 pm the DPID data the ecm broadcasts will be under the ID 0x5E8. the scan tool will request mode 0x2c to tell the ecm what pid to put in what buffer, and then I think mode 0xAA is the scan tool request to start the data broadcast. I can clarify more if it's needed. mode 0x22 is the request for the ecm to return the pid once, and the response ID will be 0x7E8
I see 5e8 21 pid1 pid2 pid3 pid4
5e8 22 pid5 pid6 pid7 pid8
But don’t user stand the reply with data load?
I’d expect to see something like
7e8 21 pid1 data load
But never see the requested pid on the responses.
I also see 30 00 00 between the pid requests
Re: E67 e38 gm lan pid info
gmtech actually described it above pretty well for the ECUs actually!
It loads all the PIDs it wants into a DPID, and then sends off a AA to start spamming it out.
For reverse engineering, I actually use an OBDX Pro to simulate the 'ecu' responses to something like Tech2win, and then I change the live data values being spammed back to work out what each byte/bit corresponds to. Its a bit of a lengthy process, but, its the reverse engineering way.
It loads all the PIDs it wants into a DPID, and then sends off a AA to start spamming it out.
For reverse engineering, I actually use an OBDX Pro to simulate the 'ecu' responses to something like Tech2win, and then I change the live data values being spammed back to work out what each byte/bit corresponds to. Its a bit of a lengthy process, but, its the reverse engineering way.
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Re: E67 e38 gm lan pid info
Genius. Great idea.Tazzi wrote: ↑Fri Jan 05, 2024 2:30 pmFor reverse engineering, I actually use an OBDX Pro to simulate the 'ecu' responses to something like Tech2win, and then I change the live data values being spammed back to work out what each byte/bit corresponds to. Its a bit of a lengthy process, but, its the reverse engineering way.
Re: E67 e38 gm lan pid info
2C FE XXXX Loads the FE DPID with the PID number xxxx
AA04FE tells the ecm to send DPID FE at a fast rate (04 is for fast rate)
ecu then starts sending 5E8 FE NN repeatedly Where NN is the pid data
you can pack multiple pids into a DPID by listing additional pids one after the after so 2C FE XXXX YYYY ZZZZ. 30 00 00 is just the flow control message from the ecu
Hope that helps!
AA04FE tells the ecm to send DPID FE at a fast rate (04 is for fast rate)
ecu then starts sending 5E8 FE NN repeatedly Where NN is the pid data
you can pack multiple pids into a DPID by listing additional pids one after the after so 2C FE XXXX YYYY ZZZZ. 30 00 00 is just the flow control message from the ecu
Hope that helps!