Tale of 3 Customer Service calls.. NOTE, you are interested in #3 which applies to most GM vehicles.
Hughesnet.. 7 hours with someone who spoke English like a native of India and the only result was a headache
Xantrex.. perhaps 10 minutes total had RMA in less than 2, rest of the time was improving my install.
Workhorse: Oil change technician failed to reset the oil life counter so I got the OIL warning... RECIPTIONIST (yes back then a genuine human answered the phone.. RECIPTIONIST no less, never talked to a service technician.
Turn engine off. Turn ignition on but do not start.
Depress accelerator pedal to the floor 3 times and release (Within a 5 second window)
After 3rd release start engine
Note: I do not recall if I had to turn key to OFF then start after the 3rd press of the pedal or just crank 'er up
But now you know.