Actron OBD II AutoScanner CP9175 Instructions Manual page 53

EST:
Electronic Spark Timing. An ignition system that allows the PCM to
control spark advance timing. The PCM determines optimum spark
timing from sensor information — engine speed, throttle position,
coolant temperature, engine load, vehicle speed, Park/Neutral switch
position, and knock sensor condition.
EVAP:
Evaporative Emissions System.
FC:
Fan Control.
Freeze Frame:
Is a "snapshot" of the operating conditions at the time of an
emission-related fault.
FTP:
Federal Test Procedure. Strict test of vehicle's emissions.
Ground (GND):
An electrical conductor used as a common return for an electric
circuit(s).
Hall Effect Sensor:
Any of a type of sensor utilizing a permanent magnet and a
transistorized Hall Effect switch. Hall Effect type sensors may be used
to measure speed and position of the crankshaft or camshaft — for
spark timing and fuel injector control.
HO2S:
Heated Oxygen Sensor. See O2S.
HVAC:
Heating, Ventilation & Air Conditioning (System.)
I/M:
Inspection and Maintenance. An emission control program.
IAC:
Idle Air Control. A device mounted on the throttle body which adjusts
the amount of air bypassing a closed throttle so that the PCM can
control idle speed.
IAT:
Intake Air Temperature (Sensor.)
ICM:
Ignition Control Module.
IMRC:
Intake Manifold Runner Control.
A-5