TROUBLESHOOTING INTRODUCTION - CONTINUED
GENERAL INFORMATION - CONTINUED
Glossary - Continued
Pulse Width Modulation (PWM). PWM is a signal
that consists of pulses of variable width. These pulses
occur at fixed intervals. Ratio of "TIME ON" versus
total "TIME OFF" can be varied. This ratio is also
referred to as a duty cycle.
Rated Fuel Limit. This term indicates maximum allowable fuel position (longest injection pulse). This position will
produce rated power for this engine configuration.
Reference Voltage. Reference voltage is a regulated and steady voltage supplied by ECM to a sensor. Reference voltage
is used by sensor to generate a signal voltage.
Sensor. A sensor is a equipment used to detect a change in pressure, temperature, or mechanical movement. Information
detected is converted into an electrical signal.
Short Circuit. A short circuit is a condition where an electrical circuit 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
wire insulation. Electrical contact with frame is made and a short circuit results.
Signal. Signal is a voltage or waveform used to transmit information, typically from a sensor to ECM.
Supply Voltage. Supply voltage is a constant voltage supplied to a component to provide electrical power required for
component to operate. Power may be generated by ECM or battery voltage supplied by vehicle wiring.
System Configuration Parameters. System configuration parameters are parameters that affect emissions and/or oper-
ating engine characteristics.
Throttle Position. Throttle position is interpretation by ECM of signal from throttle position sensor of throttle switch.
Throttle Position Sensor. Throttle position sensor is an electronic sensor connected to an accelerator pedal or hand
lever. This sensor sends a PWM signal to ECM used to calculate desired engine speed.
Top Center. Top center refers to crankshaft position when engine piston position is at highest point of travel. Engine
must be turned in normal direction of rotation to reach this point.
Total Tattletale. Total tattletale is total number of changes to all parameters stored in ECM.
Voltage Load Protection Module (VLPM). VLPM monitors electronic system voltage. VLPM will prevent fuel injec-
tion pump from injecting fuel if a high voltage condition occurs.
END OF WORK PACKAGE