GM Service Manual Online
For 1990-2009 cars only

When installing the power seat adjusters, ensure that both adjusters are parallel and in phase with each other.

When one adjuster reaches the maximum horizontal or vertical travel in a given direction before the other adjuster, alignment is necessary. Use the following procedure in order to align the phase adjusters:

Horizontal Travel

  1. Operate the seat control switch until one adjuster reaches the full-forward position.
  2. Detach the horizontal drive cable from the adjuster that has reached the full forward position.
  3. Operate the seat forward until the other adjuster reaches the full-forward position. Connect the horizontal drive cable. Inspect the horizontal travel of the seat.

Front or Rear Vertical Travel

  1. Operate the seat control switch until one adjuster has reached the fully raised position at both the front and the rear vertical travel limits.
  2. Disconnect both the front and the rear vertical drive cables from the adjuster that has reached the fully raised position. Operate the seat control switch until the other adjuster reaches the fully raised position at both the front and the rear vertical travel limits. Connect the previously removed front and rear vertical drive cables. Inspect the vertical travel by operating the adjusters through one or two complete cycles.
  3. The above operation may be repeated on an as-required basis if the adjusters do not appear to be in phase after the test cycle.