Is there any special J1587 command to initiate it? MID or PID? I guess I could sniff it out if I had the cable connection and program that 74M does. Any docs on those things?
Here is enough to be dangerous. See how this goes, I may be able to send you the full spec.
Command: ECUs on Data Link
Display: MID & SAE J1587 MID Description for user selection
Global Request: 172 / 000 / 243 / CS
Specific Request: 172 / 128 / 243 / MID / CS
Response: MID/243/n/MID/b / b …. / CS
Reference: MID 166 = Tires, Power Unit Byte “n” is the number of bytes to follow.
Bytes “b” above are not used.
Note: Some earlier systems do not respond to the Global Request. After responses to the Global
Request, if MID 166 not found on the link, use the Specific Request to detect any remaining
systems.
Command: System Type
Request: 172 / 254 / MID / 000 / 121 / CS
Response: MID/254/172/121/a/CS
Reference: The system type, 1 byte in length shown above as “a”, will have one of the following values:
1=CTIS, 3=MTVR, 4=FMTVA1.
Determine system in this order:
1.) Request Component ID (PID 243), if no response then no controller is connected.
2.) If the part number does not match any of the above, then request the system type (PID 121).
Command: Vehicle Configuration
Request: 172 / 254 / MID / 000 / 209 / CS
Response: MID/254/172/209/x/a/b/c/d/e/f/g/h/i/j/k/l/m/n/o/CS
Reference: “x” is the number of bytes following (may vary in length depending on system)
“a” is the harness configuration in decimal format, range 0-255
“b” is the maximum number of channels (electrically connected), decimal format, range 1-4
“h” is a bit-mapped byte as follows:
bits 7,6,5 – not used
bit 4 – FS: Freescale 9S12XE based ECU (0 = not used, 1 = used)
bit 3 – PTM: pressure target matrix method (0 = not used, 1 = used)
bit 2 – atm press PID (0 = not available, 1 = available)
bit 1 – target limit PID (0 = not available, 1 = available)
bit 0 – deflate style (0 = pressure based, 1 = vacuum based)
“k” total_group number of tire groups, front to rear, range 1-4
“l” total_terrain, number of terrain selections, range 3-7
“m” total_load, number of load settings, range 1-6
“n” terrain_pattern, reference to terrain text as follows:
n=10 n=11 n=12
0 = Emergency 0 = Emergency 0 = Emergency
1 = Mud/Sand/Snow 1 = Mud/Sand/Snow 1 = Off Highway
2 = Cross Country 2 = Cross Country 2 = Highway
3 = Highway 3 = Highway
4 = Air Transport