Hi Guys, posting this here as well. Have not gotten traction on the C7Z section. I went to an event this weekend and got some 1/4 mile passes in.
The car is a 15 Z06/zZ07 M7. With a Dsx lid, Halltech intake and an x-pipe. Pretty much stock. I added 18" ET Street Rs on Forgestars (the ones that fit the big brakes).
After and burnout the CEL would come on, and then limit the car on launch on rpm. I would launch to test it and it would delay the response and then kick in... I borrowed a code reader and it was P0503 VSS (vehicle speed sensor).
I unplug the battery several times, it would clear the CEL but the issue would come back right away. I played with different settings (track, tour, TCS off, on, ) it didn't matter.

There was a guy there on a 17Z that mentioned that he has heard/seen this before and an alternator replacement (stock for stock, just new) could cure it.
I havent found much info other than a post referencing that the 15Zs had bulletin from GM for a reflash that takes care of the issue?

Does anyone know anything about these codes and how to correct? I get the tire size discrepancy rules etc how how that can affect the VSS... but Im running the same setup that many do without issues like this?

 

Below is the circuit description as well as the troubleshooting flow chart…did not see any TSB’s related to this…being an intermittent issue using a lab scope would be the best way to diagnose this…may be the sensor, wiring issue or even a bad ECM…best bet is to seek out an auto electric shop in your area that uses a lab scope if you are not knowledgeable in electrical troubleshooting.