Some 1988 N cars may exhibit a condition where the dash pad bows up between the defroster duct and the windshield. This condition may be repaired using the following procedure:
1. Remove the defroster grille.
2. Loosen the two (2) screws in the defroster opening.
3. Place two (2) thicknesses of masking tape (1-1/2" wide) on the dash pad rearward of the defroster opening to prevent the dash pad from being scuffed by the drill chuck.
4. Drill a 1/8" hole in the dash pad as shown in the illustration. The hole should be centered (left to right) in the duct opening, and positioned as shown in view 'A' of the illustration so that the defroster grille will cover the hole when re-installed. The hole should be drilled at the proper angle to drill through the sheet metal lip slightly in front of duct opening as shown in the illustration.
5. Secure the dash pad to the sheet metal lip by installing an appropriately sized, black sheet metal screw with a small, beveled head (P/N 11504660 or equivalent) into the newly drilled holes in the dash pad and sheet metal.
6. Tighten the two (2) previously loosened dash pad screws.
7. Re-install the defroster grille. It may be necessary to trim some of the flashing on the bottom of the grille if there is any interference between the grille and the newly-installed screw(s)
General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.