GM Service Manual Online
For 1990-2009 cars only
  1. Block the vehicle's wheels.
  2. Turn the engine off.
  3. Move the shift lever through all the positions and then back to N (Neutral) in order to check adjustment.
  4. The pointer should cover a portion of each graphic and the flag should fill the entire window for each graphic.

  5. Have an assistant move the selector lever against the stop at the D (Drive) position while you listen for full engagement of the gears at the transmission shift lever.
  6. Adjust the shift indicator if the transmission engages properly but the shift indicator is not pointing to the correct graphic.
  7. Adjust the shift linkage if the transmission shift lever is not engaging the proper gear just before the shift lever hits the stop at the steering column.
  8. Make sure that all shift controls are not damaged and are operating smoothly before making any linkage adjustments.