TROUBLESHOOTING INTRODUCTION - CONTINUED
GENERAL INFORMATION - CONTINUED
Glossary - Continued
Coolant Level Sensor. Coolant level sensor detects absence or presence of coolant at probe. Sensor then sends a signal
Coolant Temperature Sensor. Coolant temperature sensor detects engine coolant temperature for cold mode operation
and Caterpillar Engine Monitoring.
Desired Engine Speed. Desired engine speed is input to electronic governor within ECM. Electronic governor uses sig-
nal from throttle position sensor, engine speed/timing sensor, and other sensors in order to determine desired engine
Diagnostic Code. A diagnostic code is sometimes referred to as a fault code. These codes indicate electronic system
Diagnostic Lamp. A diagnostic lamp is sometimes called "check engine light." Diagnostic lamp is used to warn opera-
tor of presence of an active diagnostic code.
Digital Sensor Return. Common line (group) from ECM is used as a ground for digital sensors.
Digital Sensors. Digital sensors produce a pulse width modulated (PWM) signal. Digital sensors are supplied with +8
VDC from ECM.
Digital Sensor Supply. +8 VDC supply from ECM is used to power digital sensor.
Direct Current (DC). Direct current is a type of current that flows consistently in only one direction.
DT, DT Connector, or Deutsch DT. This is a type of connector used on CAT machines. Connectors are manufactured
Duty Cycle. Refer to Pulse Width Modulation in this glossary.
Electronic Control Module (ECM). ECM is an engine control computer. ECM provides power to electronics. ECM
monitors data input from engine sensors. ECM acts as a governor to control engine speed.
Electronic Engine Control (EEC). Electronic engine control (EEC) is a complete electronic system. Electronic engine
control monitors engine operation under all conditions. Electronic engine control also controls engine operation under
Electronic Technician (ET). ET is a service tool that uses a software program to run on an MSD.
Engine Monitoring. Engine Monitoring is part of electronic engine control that monitors sensors and warns operator of
Engine Oil Pressure Sensor. Engine oil pressure sensor measures engine oil pressure. Sensor sends its signal to ECM.
Engine Speed/Timing Sensor. Engine speed/timing sensor provides a variable amplitude and pulse width modulated
(PWM) signal to ECM. ECM interprets this signal as crankshaft position and engine speed.
Event Code. An event code may be activated to indicate an abnormal engine operating condition. These codes usually
indicate a mechanical problem instead of an electrical system problem.
Failure Mode Identifier (FMI). This identifier indicates type of failure experienced by components. FMI has been
adopted from SAE practice of J1587 diagnostics.
Flash Programming. Flash programming is a method of programming or updating an ECM with an electronic service
tool over data link instead of replacing components.
Fuel Ratio Control (FRC). FRC is a limit based on control of fuel air ratio. FRC is used to control emission. When
ECM senses a higher boost pressure (more air into cylinder), FRC increases FRC Limit (more fuel into cylinder).
Fuel Temperature Sensor. Fuel temperature sensor detects fuel temperature. ECM monitors fuel temperature and
adjusts calculated fuel rate accordingly.