1997 Ford Aerostar Owner's Manual - Page 176

When to use Drive You will note there is not a drive position on your gearshift indicator. However, you will find a transmission control switch labeled OVERDRIVE OFF located on the end of the gearshift lever. With overdrive canceled and the OVERDRIVE OFF illuminated, the transmission will operate in gears one through four. This is useful if you experience frequent downshift/upshift conditions, when operating a heavy load or in hilly terrain, or if additional engine braking is useful. However, shift back to j (Overdrive) whenever practical for optimum powertrain cooling and fuel economy. This can be accomplished by pushing the transmission control switch again, to cancel the OVERDRIVE OFF control and light. When to use 2 (Second) With the gearshift in the 2 (Second) position, more engine braking is provided. Use the 2 (Second) position to drive up moderately steep grades, to start up slippery roads, or to provide moderate engine braking on downgrades. DO NOT GO FASTER THAN 55 mph (88 km/h) IN THIS GEARSHIFT POSITION. When to use 1 (Low) With the gearshift in the 1 (First) position, maximum engine braking is provided. This position provides 1 (First) gear operation only with no automatic upshifts. To obtain upshifts, the gearshift must be moved out of this position. Use the 1 (First) position to drive up steep grades or to provide maximum engine braking on downgrades. 176