Filter
Top Products
39
EGR:
Exhaust Gas Recirculation. The EGR sys-
tem recirculates exhaust gases back into
the intake manifold to reduce NOx emis-
sions. The EGR valve controls the flow of
exhaust gases back into the intake mani-
fold. Some EGR valves are operated with a
vacuum signal while others are electrically
controlled. The amount of EGR valve open-
ing determines the flow through the valve.
EGR Recirculation is only used during warm
engine cruise conditions. EGR flow at other
times can cause stalling or no starts. There
are many different types of EGR systems
controlled by the PCM.
Engine Parameters:
This is the translated information that is dis-
played on the system tester screen. Param-
eters will include the information inputs and
the output information from the PCM. En-
gine Parameters are often referred to as
PIDs (Parameter Identification Data).
EPA:
Environmental Protection Agency.
ESC:
Electronic Spark Control. This is an igni-
tion system function that works on vehicles
having a knock sensor mounted on the
engine block. The knock sensor is wired
to circuitry in a separate module (early ver-
sion) or inside the PCM (later versions). If
the sensor detects engine knock, the ESC
function alerts the PCM that will immedi-
ately retard the spark to eliminate the
knocking condition.
EST:
Electronic Spark Timing. An ignition system
where the PCM controls the spark advance
timing. A signal called EST goes from the
PCM to the ignition module that fires the
spark coil. The PCM determines optimum
spark timing from sensor information
engine speed, throttle position, coolant tem-
perature, engine load, vehicle speed, Park/
Neutral switch position, and knock sensor
condition.
EVAP:
Evaporative Emissions System.
EVRV:
Electronic Vacuum Regulator Valve. This
actuator is controlled by the PCM and is
used to control the amount of vacuum ap-
plied to a vacuum-operated device.
Fuel Injector:
An electronically controlled flow valve. Fuel
injectors are connected to a pressurized
fuel supply (fuel pressure is created by a
fuel pump). No flow occurs when the injec-
tor is off (not energized). When the injector
is energized, it opens fully, allowing fuel to
flow. The PCM controls fuel delivery by vary-
ing the amount of time the injector sole-
noids are turned on.
Fuel Pump Relay:
The PCM energizes this relay to apply power
to the vehicle fuel pump. For safety rea-
sons, the PCM removes power from the
fuel pump when ignition signals are not
present.
Fuel Pump Signal:
This is a wire between the PCM and the
fuel pump motor power terminal. The PCM
uses this signal to verify when voltage is at
the fuel pump (for diagnosing fuel pump
problems).
Gear Switches:
These are switches (usually two) located
inside certain automatic transmissions.
The PCM monitors the switches to deter-
mine what transmission gear is engaged.
The switches are activated by hydraulic
pressure and may be normally open or
closed, depending on the vehicle. The PCM
uses gear information for control of the
torque converter clutch, some emission
systems, and for transmission diagnostic
purposes.
Ground:
Ground is the return path for current to flow
back to its source (Usually the negative bat-
tery terminal). It is also the reference point
from which voltage measurements are
made (the connection place for the nega-
tive (-) test lead from a voltmeter).