FUEL SYSTEM CONTINUED
Engine Electronic Control System
The engine electronic control system provides complete electronic control of all engine functions. The engine
electronic control system consists of the following three types of components: input, control, and output. Sensors
monitor engine operating conditions. This information is sent to the engine Electronic Control Module (ECM), which
has three main functions. The engine ECM provides power for the engine electronics and monitors input signals
from the engine sensors.
The engine ECM also acts as a governor to control engine rpm. The engine ECM stores active faults, logged faults,
and logged events. The Personality Module is the software in the engine ECM, which contains the specific maps
that define power, torque, and rpm of the engine. The engine ECM sends electrical current to the output
components in order to control engine operation. The engine ECM has the following connectors: two 70-pin
harness connectors, one engine harness connector, and one vehicle harness connector. The vehicle harness
connects the engine ECM to the engine control portion of the vehicle harness.
The following features are part of the engine electronic control system:
Cold start strategy
Coolant temperature warning indicator
Automatic altitude compensation
Variable injection timing
Electronic engine speed governing
These features result in: precise engine speed control, very little smoke, faster cold starting, and built-in engine
The engine ECM consists of the following two main components: the electronic control module and the personality
The engine ECM is a computer and the personality module is the software for the computer. The personality
module contains the operating maps, which define the following characteristics of the engine:
The engine ECM, the personality module, the sensors, and the unit injectors work together in order to control the
engine, but can not control the engine alone.
The engine ECM determines a desired rpm based on the following criteria:
Certain diagnostic codes
Vehicle speed signal
The engine ECM maintains the desired engine rpm by sensing the actual engine rpm and then calculates the
amount of fuel needed to be injected in order to achieve the desired rpm.