For 1990-2009 cars

1. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle.
2. Check for obvious deterioration of the floor pan.
3. Check for loose dirt and corrosion around the inside of the floor pan reinforcement member access holes. This is the first indication that corrosion may exist in hidden areas, and repairs may be required before the final cleaning and protective treatment is performed.
4. Using a chisel, ensure that the drain provisions in the floor pan reinforcement members are open. There are drain holes in the body side panels also. These holes can be opened using a punch or a drift. The side panel drain holes are in the rear section of the rocker panels, and in the lower rear quarter panels.