Powertrain Control Module

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If engine speed becomes unstable after disconnecting battery, reset Powertrain Control Module (PCM) using following method:

Place transmission/transaxle selector lever in Park position and turn engine off.
Start engine.
Turn off air conditioning.
Allow engine to reach normal operating temperature.
Turn engine off and on again.
Allow engine to idle for about 10 minutes.
When engine speed stabilizes, resetting procedure is complete.