B4000 Regular Cab 4WD V6-4.0L OHV (1997)
Powertrain Control Module (PCM): Description and Operation
Keep Alive Memory
KEEP ALIVE MEMORY (KAM)
PCM stores data in KAM about vehicle operating conditions, and then uses data to compensate for component variability. KAM remains powered
when ignition is off so that information is not lost until PCM connector disconnected or battery cable disconnected.