Originally posted by Mustang:
Here's a bit more info from The Standard Motor web site.

So what does P1000 mean? A P1000 code means that ALL of the OBD II monitors have not been completed since the ECMâ??s memory has been cleared. It is not necessary to clear the P1000 code unless you are performing a state inspection that requires it to be cleared. This code could also be the result of the customerâ??s driving pattern not permitting all of the OBD II monitors to complete their drive cycle. A Ford OBD II drive cycle is a specific driving pattern which is used to allow the various OBD II monitors to run and be completed. The requirements for the drive cycle to complete are that all â??Tripâ? monitors are completed. A trip is defined as an engine running, vehicle moving, and the â??Tripâ? monitor has been completed. Therefore, if all OBD II trips have been completed, you have successfully completed the OBD II drive cycle. All scanners will display
â??Trip Statusâ? as a â??Yesâ? or â??Noâ?. A â??Yesâ? simply means that a monitor has run. Regarding monitors, 1994 & 1995
Ford vehicles use five separate monitors. 1996 & later vehicles use as many as nine. Each monitor has its own criteria to run and complete. Each monitor is actually a test of a particular systemâ??s ability to meet and stay within operating parameters. When ALL of the monitors have run, the P1000 code will be erased. It is best to refer to the specific modelâ??s manual to determine the exact drive
cycle procedure. When performing a drive cycle, a smooth, steady foot on the accelerator will be to your advantage in completing the cycle. Abrupt speed changes and erratic
changes in TPS voltage will cause the ECM to take longer to complete, and may even abort certain tests. Avoid wide-open throttle, and exercise caution while driving and viewing the scan tool. Most of the scan tools will indicate each
monitorâ??s status, and whether or not it has been completed. Some monitors are run continuously, and as a result will not indicate a completed status. If for some reason a â??tripâ? was not completed during a drive cycle, the ECM will not need to re-run all of the monitors. It will begin where it had left off, so it is not necessary to repeat the entire process. With OBD II if you perform a repair and want to verify that you did repair the vehicle, you must keep in mind: the systemâ??s criteria for setting a code, and whether the ECM is looking for two consecutive faults. If
this is the case, then itâ??s mandatory to view the monitorâ??s status and make sure itâ??s completed. Donâ??t rely on the MIL light, because it may take two trips to come on, and that second trip will be when the customer is driving the vehicle.
Mike Nieto-
Ford Specialist

Hope this helps some.