Actron CP9175 OBD II AutoScanner - Manual (Page 56)

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Open Loop (OL):
A control system mode that does not monitor the output to verify if the
desired achieved results. A fuel delivery system will usually operate in
open loop mode during cold engine warm-up because the oxygen
sensors are not yet ready to send a signal. Without the oxygen sensor
signal, the computer cannot check the actual results of combustion.
PCM:
Powertrain Control Module. The “brains” of the engine control system
and transmission control system housed in a metal box with a number
of sensors and actuators connected via a wiring harness. Its job is to
control fuel delivery, idle speed, spark advance timing, and emission
systems. The PCM receives information from sensors, then energizes
various actuators to control the engine. The ECM (Engine Control
Module) is another name used for the PCM.
Pending Codes:
Also referred to as Continuous Memory codes and Maturing
Diagnostic Trouble Codes. Pending Codes may be set by emission
related powertrain components and systems. If the fault does not
occur after a certain number of drive cycles, memory erases the code.
PID:
Parameter Identification. Identifies an address in memory which
contains vehicle operating information.
PNP:
Park/Neutral Position. This is a switch that tells the PCM when the gear
shift lever is in the Park or Neutral position. When in Park or Neutral,
the PCM will operate the engine in an “idle” mode.
PROM:
Programmable Read-Only Memory. The PROM contains
programming information the PCM needs to operate a specific vehicle
model/engine combination.
PSPS:
Power Steering Pressure Switch.
Purge Solenoid:
Controls the flow of fuel vapors from the carbon canister to the intake
manifold. The canister collects vapors evaporating from the fuel tank,
preventing them from escaping to the atmosphere and causing
pollution. During warm engine cruise conditions, the PCM energizes
the Purge Solenoid so the trapped vapors are drawn into the engine
and burned.
PWM:
Pulse Width Modulated.