Actron OBD II AutoScanner CP9135 Instructions Manual page 32

NOx:
Oxides of Nitrogen. A pollutant. The
EGR system injects exhaust gases into
the intake manifold to reduce these
gases at the tailpipe.
O2S:
Oxygen Sensor. Generates a voltage of
0.6 to 1.1 volts when the exhaust gas is
rich (low oxygen content). The voltage
changes to 0.4 volts or less when the
exhaust gas is lean (high oxygen
content). This sensor only operates
after it reaches a temperature of
approximately 349°C (660°F). O2
sensors are usually found both
upstream and downstream of the
catalytic converter. The PCM uses
these sensors to fine tune the air-fuel
ratio and to monitor the efficiency of the
catalytic converter. See Bank 1, Bank
2, Sensor 1, Sensor 2.
ODM:
Output Device Monitor.
OBD II:
On-Board Diagnostics, Second
Generation. OBD II is a U.S.
Government-mandated standard
requiring all cars and light trucks to
have a common data connector,
connector location, communication
protocol, DTCs and code definitions.
OBD II first appeared on vehicles in
late 1994, and is required to be present
on all cars sold in the US after January
1, 1996.
Open Loop (O/L):
A control system mode that does not
monitor the output to verify if the
desired results were achieved. 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.
P/N:
Park/Neutral Switch. This switch 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.
A-4
PCM:
Powertrain Control Module. The
"brains" of the engine 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).
PROM:
Programmable Read-Only Memory.
The PROM contains programming
information the PCM needs to operate
a specific vehicle model/engine
combination.
Pending Codes:
Also referred to as Continuous Memory
codes and Maturing Diagnostic Trouble
codes. These codes are set when
intermittent faults occur while driving. If
the fault does not occur after a certain
number of drive cycles, the code is
erased from memory.
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.
Reluctance Sensor:
A type of sensor typically used to
measure crankshaft or camshaft Speed
and/or position, driveshaft speed, and
wheel speed
ROM:
Read-Only Memory. Permanent
programming information stored inside
the PCM, containing the information the
PCM needs to operate a specific
vehicle model/engine combination.
SAE:
Society of Automotive Engineers.
Glossary