Conditions for Running the DTC

WARNING: This page is about a different car, the 2007 Hummer H2. However, it is still accessible from the selected car via links, so may be relevant.

DTC P2108 or U0107 is not set.
The ignition switch is in the Crank or Run position.
The ignition voltage is more than 5.23 volts.
The TAC system is not in the battery saver mode.
DTC P1516 runs continuously once the above conditions are met.