Yes I wish I had a excel spreadsheet that organized my messages like that!To determine the specific modules involved you will need to check the Source & Target data in the messages. As an example (apologies for the eye chart!) , here is a data captured from my '03 Suburban as I lock the doors:
View attachment 107931
Modules present are 40 - BCM; A0 - Driver Door Module; & A1 - Passenger Door Module.
In the first line the Source 40 - BCM sends out a door lock command to Target C4 - Door Locks - Command. The Driver Side & Passenger Side recognize this Command message and respond with acknowledgements. Line 2 is from Source A0 Driver Door Module to Target C5 - Door Locks Status; line 3 is from Source A1 - Passenger Door Module to C5 - Door Locks Status. The BCM recognizes these as acknowledgements.
Edit: I cannot speak to C7 as I do not have specific examples. That said, the process would be the same.
88 53 10 04 C4 (appears to be engine status, runstatus, 04 = not running? plus checksum)
88 53 10 84 E2 (appears to be engine status, runstatus, 84 = running? plus checksum)
- I think those two basically just use the msb of the secondary ID to indicate engine running or not
68 EA 10 0A 09 46 (I see this very regularly in my log. From discussion in this thread I think it's PRNDL indicator position... but this VCM was converted to manual by hptuners, so who knows how it configured the transmission segment, this may be insane data that doesn't match any factory OS bus message.)
49 92 10 01 BE (vehicle security message of some sort. VATS is disabled on this VCM, I have no idea what the rest of this data means.)
8A EA 10 A0 *3bytes*
8A EA 10 20 *3bytes* (displays, unknown secondary IDs, data varies. I would love to know what these are, just because I'm curious.)
88 1B 10 10 0E D2 6B (engine rpm, but secondary ID of 10 doesn't show in my pdf, what format are the next two bytes? I was idling at 500-750ish RPM so I doubt it's just plain RPM, doesn't seem to be ignition events per minute either since that would be 948rpm for a 4stroke V8.)
Thanks very much for getting so much of this info documented up front. It's definitely helped me get started on my current project. I'm seeing some weird undocumented (at least in the 99 version of the standard... anyone got a later J2178-4 handy?) secondary IDs on more common primary IDs, as well as some things I just thought were interesting.
This is all relating to a 03 Savana 3500 with an LQ4, at least that's what the engine came from. No other modules on bus, only VCM. OS ID 12593058.
Some interesting messages I see:
88 53 10 04 C4 (appears to be engine status, runstatus, 04 = not running? plus checksum)
88 53 10 84 E2 (appears to be engine status, runstatus, 84 = running? plus checksum)
- I think those two basically just use the msb of the secondary ID to indicate engine running or not.
68 EA 10 0A 09 46 (I see this very regularly in my log. From discussion in this thread I think it's PRNDL indicator position... but this VCM was converted to manual by hptuners, so who knows how it configured the transmission segment, this may be insane data that doesn't match any factory OS bus message.)
49 92 10 01 BE (vehicle security message of some sort. VATS is disabled on this VCM, I have no idea what the rest of this data means.)
68 13 10 11 00 00 66 (throttle pedal position. Appears to report infrequently but all I did was idle it during this log.)
88 09 10 22 41 BE (engine torque. Unknown secondary ID. Last byte and csum vary. Maybe torque contribution per cylinder???)
8A EA 10 A0 *3bytes*
8A EA 10 20 *3bytes* (displays, unknown secondary IDs, data varies. I would love to know what these are, just because I'm curious.)
88 1B 10 10 0E D2 6B (engine rpm, but secondary ID of 10 doesn't show in my pdf, what format are the next two bytes? I was idling at 500-750ish RPM so I doubt it's just plain RPM, doesn't seem to be ignition events per minute either since that would be 948rpm for a 4stroke V8.)
The great news (at least for me) is that engine oil pressure, fuel level, coolant temp, vehicle speed all report accurately per SAE J2178-4 tables, and that's most of the way to what I need for my custom dash project, so aside from RPM this is mostly academic for me. If you want more data from more donor vehicles, I've attached a copy of the log I took... but be warned it's from PuTTY w/o timestamps not the android app you use.
Welcome to the forums!I have a 2002 Tahoe with a E-ROD LS3 6.2 that only communicates with CAN. So using this forums information and others; am intending to build a protocol converter between CAN and J1850VPW.
If anyone knows of such a device I would love to hear about it - here.
I fear that you may be confusing me with @TJBaker57. He has truly done a ton of work and made countless posts, generously sharing what he's learned. I'm a relative newcomer here (but a long-time SAE J1850 experimenter, both VPW and PWM, with a tiny smattering of CAN experience mixed in). I try to share what I've learned too, though.You have been doing a mountain of work helping everyone on this forum [...]
I'm a big fan of Linux. It's really all I use, for well over 20 years now. All of my OBD2 utilities (to gather and analyze vehicle data, typically for diagnosis) run on Linux desktop/laptop PCs. I'd heard of 'Automotive Grade Linux' but haven't really spent any time looking into it, so thanks for mentioning it -- another rabbit hole, indeed!I'm making a little progress but I keep falling in rabbit holes - like - watch out:
Automotive Linux