performs several functions
ratios via Injector
Pulse Width and Ignition Timing.
These “outputs” are controlled using
the “inputs” received from all the
sensors and then comparing these
reading against a set of data tables
burned into the PCM.
These “memory tables” are the brains
that keep the engine running at low
emissions and peak economy
across the RPM band
The memory tables change. They are
“adaptive”, based on sensor
readings, driving habits, engine
Over time, the PCM Memory Tables
become tuned to your engine.
Disconnecting the battery for 15 to
20 minutes will reset the PCM to get
rid of a Check Engine Light or
Error Codes stored in the PCM.
This DOES NOT reset the Adaptive
Memory Tables in the PCM.
This procedure will Erase the
“Adaptive Memory” stored inside the
TJ PCM and allow a new “Adaptive
to be developed.
After performing this procedure the
PCM will re-learn and store into
Adaptive Memory your engines
Disconnect the POSITIVE battery
Terminal and touch it to ground for
30 seconds. (This is to discharge
the PCM capacitors, which maintain
the Adaptive Memory.
Reconnect the Battery Cable
Turn Ignition Switch to the “On”
position but DO NOT start the engine
Turn Headlight “On”
Turn Headlights “Off”
Turn Ignition Key “Off”
Adaptive memory has now been
flashed, or erased from the PCM.
When you start the engine it will be
running off a set of pre-programmed
tables that come with the PCM from
When you get the engine up to
operating temperature the PCM will
start to collect data for the
The PCM will collect data for
Adaptive Memory for the first 50
A warm-up cycle happens when all of
the following conditions exist.
Engine is running
A raise of 40F in engine temperature
must occur ABOVE the engine
temperature at start-up
Engine Coolant Temp must reach at
least 160 F.
Once your engine has gone through 50
warm-up cycles in at least a
500-mile distance the PCM adaptive
memory is set. It will not change
unless you flash it out and start
all over again.