DTC P0601-P0607, P1600, P1621, P1627, P1680, P1681, P1683 & P2610: Pcm Internal Microprocessor Integrity: Description
WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2003 Pontiac Grand Prix, 2003 Pontiac Bonneville, 2003 Chevrolet Monte Carlo, 2003 Chevrolet Impala, and 2003 Buick Regal. However, it is still accessible from the selected car via links, so may be relevant.
This diagnostic applies to internal microprocessor integrity conditions within PCM. This diagnostic also addresses if PCM is not programmed.