1997 Ford Aerostar Owner's Manual - Page 21

If your engine overheats: 1. 2. 3. Pull off the road as soon as it is safely possible. Turn off the engine. Let the engine cool. DO NOT REMOVE COOLANT SYSTEM FILL CAP UNTIL THE ENGINE IS COOL. Check the coolant level following the instructions on checking and adding coolant to your engine. Refer to Engine coolant in the Index. If you do not follow these instructions, you or others could be injured. 4. Engine coolant temperature gauge Speedometer The speedometer tells you how many miles (kilometers) per hour your vehicle is moving. Your vehicle contains a speedometer which receives its input from the Anti-Lock brake sensor. The speedometer is also used to provide a speed signal for correct operation of the vehicle's Powertrain Control Module (PCM), electronic transmission, and speed control (if so equipped). Because of this, it is very IMPORTANT to change the speedometer's internal conversion constant if the size of the tires on the vehicle is changed. Changing the conversion constant to the proper value when 18