GM Service Manual Online
For 1990-2009 cars only

Inspect the frame to body alignment by inserting a 16 mm (5/8 in) drill bit into the frame to body alignment holes.

  1. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  2. Inspect for obvious floor pan deterioration.
  3. Inspect for loose dirt and corrosion around the inside of the floor pan reinforcement member access holes. This is the first indication that corrosion exists in hidden areas.
  4. Perform all repairs before the final cleaning and the protective treatment.

  5. Using a chisel, ensure that the drain provisions in the floor plan reinforcement members are open.
  6. Open the drain holes in the body side panels using a punch and a drift.

  7. The side panel drain holes are located in the rear section of the rocker panels and in the lower rear quarter panels.