Bosch OBD 2220 INFO SCAN User Manual page 39

injectors are mounted in the intake manifold, and fired in
groups rather than individually.
NOx:
Oxides of nitrogen. The system EGR and Camshafts
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 oper-
ates after it reaches a temperature of approximately
349ºC (660ºF). 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 con-
verter. See Bank 1, Bank 2, Sensor 1, Sensor 2.
OBDII:
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.
ODM:
Output device monitor
Open loop (OL):
A control system mode that does not monitor the output
to verify if the desired results were achieved. A fuel
delivery system usually operates 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 and
transmission control systems 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 matur-
ing diagnostic trouble codes. Pending codes may be set
by emission related powertrain components and sys-
tems. 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 mem-
ory which contains vehicle operating information.
PNP:
Park/neutral position. A switch that tells the PCM when
the gear shift lever is in the park or neutral position.
Bosch Automotive Service Solutions Inc.
OBD 2220 Info Scan | User guide | 39 | en
When in park or neutral, the PCM operates 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 ener-
gizes 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.
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.
RPM:
Revolutions per minute
SAE:
Society of Automotive Engineers
Scan tool:
A device that interfaces with and communicates informa-
tion on a data link.
SDM:
Sensing and diagnostic module
Sensor x:
A standard term used to identify the location of oxygen
sensors. Sensor 1 is located upstream of the catalytic
converter. See O2S, Bank 1, Bank 2.
Sensor:
Any device that reports information to the PCM. The job
of the sensor is to convert a parameter such as engine
temperature into an electrical signal that the PCM can
understand.
SFI or SEFI:
Sequential fuel injection or sequential electronic fuel
Injection. A fuel injection system that uses one or more
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