GM Service Manual Online
For 1990-2009 cars only
  1. Turn the ignition switch to ON.
  2. Using a jumper, connect the DLC terminals 11 (Tc) and 3 (E1).
  3. Check if the CRUISE indicator lamp flashes rapidly. This indicates that there are no DTCs stored in the cruise control module memory.
  4. The CRUISE indicator lamp will display any DTCs that are stored by flashing a numbered sequence. If more than one DTC is stored, they will be flashed sequentially from the lowest to the highest. Perform the cruise control OBD system check to determine the cause of the malfunction within the cruise control system.