This document is printed from SPI². Not for RESALE
Relay – A relay is an electromechanical switch. A
flow of electricity in one circuit is used to control the
flow of electricity in another circuit. A small current or
voltage is applied to a relay in order to switch a much
larger current or voltage.
Secondary Speed/Timing Sensor – This sensor
determines the position of the camshaft during engine
operation. If the primary speed/timing sensor fails
during engine operation, the secondary speed/timing
sensor is used to provide the signal.
Sensor – A sensor is used to detect a change in the
pressure, in the temperature, or in mechanical
movement. When any of these changes are detected,
a sensor converts the change into an electrical signal.
Short Circuit – A short circuit is a condition that has
an electrical circuit that is inadvertently connected to
an undesirable point. An example of a short circuit is
a wire which rubs against a vehicle frame and this
rubbing eventually wears off the wire insulation.
Electrical contact with the frame is made and a short
circuit results.
Signal – The signal is a voltage or a waveform that is
used in order to transmit information typically from a
sensor to the ECM.
Suction Control Valve (SCV) – The SCV is a
control device in the high-pressure fuel pump. The
ECM controls the pressure in the fuel rail by using this
valve to control the amount of fuel that enters the
chambers in the pump.
Supply Voltage – The supply voltage is a continuous
voltage that is supplied to a component in order to
provide the electrical power that is required for the
component to operate. The power may be generated
by the ECM or the power may be battery voltage that
is supplied by the engine wiring.
System Configuration Parameters – System
configuration parameters are parameters that affect
emissions and/or operating characteristics of the
engine.
““T”” Harness – This harness is a test harness that is
designed to permit normal circuit operation and the
measurement of the voltage simultaneously.
Typically, the harness is inserted between the two
ends of a connector.
Throttle Position – The throttle position is the
interpretation by the ECM of the signal from the
throttle position sensor or the throttle switch.
Throttle Position Sensor – The throttle position
sensor is an electronic sensor that is usually
connected to an accelerator pedal or a hand lever.
This sensor sends a signal to the ECM that is used to
calculate desired engine speed.
Throttle Switch – The throttle switch sends a signal
to the ECM that is used to calculate desired engine
speed.
Top Center Position – The top center position refers
to the crankshaft position when the engine piston
position is at the highest point of travel. The engine
must be turned in the normal direction of rotation in
order to reach this point.
Wait To Start Lamp – This is a lamp that is included
in the cold starting aid circuit in order to indicate when
the wait to start period has expired. The glow plugs
have not deactivated at this point in time.
Warning Lamp – The warning lamp is used to warn
the operator of the presence of an active diagnostic
code.
Wastegate – This is a device in a turbocharged
engine that controls the maximum boost pressure that
is provided to the inlet manifold.
Wastegate Regulator – The wastegate regulator
controls the pressure in the inlet manifold to a value
that is determined by the ECM. The wastegate
regulator provides the interface between the ECM
and the mechanical system that regulates inlet
manifold pressure to the desired value that is
determined by the software.
UENR0623 49
Engine Operation
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