PCM Fast Learn Mode

The PCM performs several functions controlling Air Fuel 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
 and sensor tolerances.

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.

Forced Flash

This procedure will Erase the “Adaptive Memory” stored inside the TJ PCM and allow a new “Adaptive Memory”
to be developed.

After performing this procedure the PCM will re-learn and store into Adaptive Memory your engines
performance characteristics.

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 the factory.

When you get the engine up to operating temperature the PCM will start to collect data for the “Adaptive Memory”.

The PCM will collect data for Adaptive Memory for the first 50 Warm-up Cycles.

Warm-up Cycle

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.