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• • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Glossary
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 PCM is also known as the ECM (Engine Control Module).
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,
the code is erased from memory.
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
PZM:
Platform Zone Module
QDM:
Quad Driver Module
RAM:
Random Access Memory
Relay:
An electromechanical device in which connections in one circuit are switched
B
Reluctance Sensor:
A type of sensor typically used to measure crankshaft or camshaft Speed and/or
position, driveshaft speed, and wheel speed
• • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • B – 7
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