1996 Ford F250 Owner's Manual - Page 374

Readiness for Inspection/Maintenance Testing In some localities it may become a legal requirement to pass an Inspection/Maintenance (I/M) test of the On-Board Diagnostic (OBD) II system. If the vehicle's powertrain system or its battery has just been serviced, the OBD II system is reset to a not ready for I/M testing condition. To prepare for I/M testing, the law specifies a "need for additional mixed city and highway driving to complete the check" of the OBD II system. As soon as all of the OBD II system checks are successfully completed, the OBD II system is set to the ready condition. The amount of driving required to reach the ready condition varies with individual driving patterns. To complete this requirement in the minimum amount of time, refer to the OBD II Drive Cycle defined below. If the vehicle owner cannot or does not want to do the additional driving required by law, a service center can perform this drive cycle as it would any other type of repair work. OBD II Drive Cycle The engine must be warmed up and at operating temperature before proceeding with the drive modes of the following OBD II Drive Cycle. 1. 2. 3. Start the engine. Drive or idle (in neutral) the vehicle for 4 minutes. Idle the vehicle in drive (neutral for manual transmission) for 40 seconds. Accelerate the vehicle to 45 mph (72 km/h) at 1/4 to 1/2 throttle for 10 seconds. 375