GM Service Manual Online
For 1990-2009 cars only

If for some reason, brake application fails to release the shifter electronically, or if service or towing requires the car to be shifted out of park without running the engine, the system can by-passed. To by-pass the system:

  1. Turn the ignition key to the ACC position.
  2. Apply the regular brakes.
  3. Shift to N (Neutral). The vehicle may now be operated normally.