GM Service Manual Online
For 1990-2009 cars only

Step

Action

Normal Result(s)

Abnormal Result(s)*

1

  1. Turn the engine off.
  2. Turn the ignition switch to RUN.
  3. Attempt to shift the vehicle out of PARK.

The vehicle does not shift out of PARK.

Automatic Transmission Shift Lock Control Inoperative

2

  1. Depress the brake pedal.
  2. Attempt to shift the vehicle out of PARK.

The vehicle shifts out of PARK.

Automatic Transmission Shift Lock Control Always On With Ignition in RUN

* Refer to the appropriate symptom diagnostic table for the applicable abnormal result.