1997 Ford Aerostar Owner's Manual - Page 15

Check Engine Warning Light This light illuminates when the engine's Emission Control System requires service. It will also illuminate when the ignition key is in the ON position and the engine is off. Check engine warning light Electronic 4-Wheel Drive Warning Light (If equipped) The Electronic 4-Wheel Drive Warning Light illuminates when the Electronic 4-Wheel Drive system is not working properly. This light illuminates briefly when you turn the ignition key to the ON position, but should turn off when the engine starts. If the light does not illuminate when you turn the ignition to the ON position, or if it illuminates and stays on when you are driving, have your vehicle serviced as soon as possible. The 4WD light will go off after a few seconds and stay off if all systems are operating correctly. If a problem is detected, the 4WD warning light will flash a certain number of times indicating the location of the problem. The flashing will continue until the problem is corrected. Each time the ignition key is turned on, the controller will detect the problem and flash the signal. The 4WD system remains safe to operate and the vehicle should be returned for service. 12