Enhanced PIDs beyond $00-$1F?

[dimented24x7]

Im working with a 98 vortec PCM, and in the code I located the datalink controller transmit/recieve routines, and the routine that transmits the requested PIDs for diagnostics. I was hoping that the routines that handle the mode 1/2 diagnostics communications would support lots of PIDs and hand me everything on a silver platter, but it doesnt look like its that easy. In the index of supported PIDs, the base PIDs only go up to $1F. After that, theyre double byte values with the most significant byte being $11, $12, $13, etc. and then the least significant byte being a number that looks like it corresponds to a PID. Are these enhanced PIDs that support additional data? If so, is there information similar to the SAE J1979 on what enhanced PIDs are available and what they do, or are they specific to GM?

[EC_Tune]

Most likely specific to GM. You would need to see what they point to in the code to find out what they are reporting.

[dimented24x7]

Im not as concerned about being able to transmit them, but I was hoping that if I could find out what they transmit, then I could get more information beyond what teh base PIDs give me. Those allowed me to get a handfull of outputs defined on the serial A/D converter as well as the MAF and RPM, which allowed me to make some good headway, but not enough to really map out the tables in the calibration section.

Ultimatly, Id like to map out the majority of the engine code and tables. From my experience, even though its six months or so up front of work, it really cuts down the time needed to get the car running good.

Oh well... I'll have to do it the old fashioned way. Hook something up to each of the inputs and see what changes.

[Chris@HPTuners]

they are GM specific and usually the 11xx pids are PCM dependant.