yo!
The Keep Alive Memory (KAM) within the processor must always have voltage supplied to it. This voltage is supplied by the Keep Alive Power (KAPWR) circuit (Pin 1) that connects directly to the battery. KAM contains adaptive parameter tables that allow the processor to adapt to different operating requirements. It also contains the Continuous Memory codes. Continuous Memory codes will be erased any time KAPWR is disconnected (i.e. battery disconnected, processor disconnected, breakout box installed, open in the wire, etc.). If KAM fails within the processor, all Continuous codes will also be erased.
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Powertrain Control Module KAM Test Error Indicates the PCM has experienced an internal memory fault. However there are external items that can cause this DTC. Reprogramming
Battery terminal corrosion
KAPWR to PCM interrupt/open
Loose battery connection
Damaged PCM (less likely)
...basically, if the truck is running fine, don't worry.
Now, in my 96 and in many Ford vehicles, a Code Reader Will NOT Power up; 96 Bronco & all Ford; Check the fuse for the cigarette lighter. It is shared with the OBDII connector power and is commonly blown due to bad wire routing around ash tray framework by Ford! or by shorted/high amp draw by Lighter element.
EDIT; forgot a major thAng, sorry, got caught up in multi tasking;
Clearing Keep Alive Memory:
To clear the KAM, disconnect the battery negative terminal for five minutes or more (preferably 15 minutes).
Adaptive Strategy Relearn Procedure:
After repairs have been made and the KAM cleared drive the vehicle for at least ten miles to allow the PCM to relearn the values for optimum performance.
Note: During the ten mile relearn drive, the vehicle may exhibit some driveability symptoms. These should be eliminated when the KAM has relearned the operating values.
If I confused you, sorry, ask again.