ENGINE SYSTEMS CONTINUED
Low Battery Voltage Elevated Idle Feature
This feature temporarily elevates low idle speed when the machine is not working and the battery level is less than
24.5 Volts DC. The engine speed will increase to approximately 1200 rpm when the feature is active.
Primary engine position is a passive sensor. The timing wheel is located on the crankshaft. The primary speed/
timing sensor receives a signal from the teeth on the timing wheel. The extra space on the timing wheel provides
one revolution per space. The space is oriented so that it is 40 degrees past top center.
When the engine is cranking, the engine ECM uses the signal from the secondary speed/timing sensor in the fuel
injection pump. When the engine is running, the engine ECM uses the signal from the primary speed/timing sensor
on the crankshaft. This speed/timing sensor is the primary source of the engine position.
The inlet manifold (boost) pressure sensor and the engine oil pressure sensor are active sensors.
The inlet manifold (boost) pressure sensor provides inlet manifold pressure data to the engine ECM. The engine
ECM uses this data to control air/fuel ratio. This reduces engine smoke during transient conditions. The operating
range of the inlet manifold (boost) pressure sensor is up to 49 psi (338 kPa) for engines with standard power and
up to 64 psi (441 kPa) for engines with high power.
The engine oil pressure sensor provides engine oil pressure data to the engine ECM. The engine ECM uses this
data to warn the operator of possible conditions that can damage the engine. This includes the detection of an oil
filter that is blocked. The operating range for the engine oil pressure sensor is 8 to 50 psi (55 to 345 kPa).
The inlet manifold temperature sensor and the coolant temperature sensor are passive sensors. Each sensor
provides temperature data to the engine ECM. The engine ECM uses this data to control fuel delivery and fuel
injection timing. It is also used for engine monitoring. The operating range for these sensors is -40°F to 302°F
(-40°C to 150°C).
A diagnostic code indicates that the engine ECM has detected an electrical problem or an electronic problem with
the engine control system. When the engine ECM generates a diagnostic code, it also logs the time and the
number of occurrences of the fault. In some cases, an active fault can affect engine performance. Therefore, if the
operator identifies a performance problem, a diagnostic code may indicate the cause of the problem.
An event code indicates that the engine ECM has detected an abnormal engine operating condition. The engine
ECM will log the occurrence of an event code. An event code does not indicate an electrical or electronic
malfunction. For example, if the temperature of the coolant in the engine is higher than the permitted limit, the
engine ECM will detect the condition and log it as an event code.
Factory passwords prevent unauthorized de-programming of the system and unauthorized removal of logged
events. They also protect system configuration parameters, which affect power rating and emissions. Passwords
also allow control of certain programmable engine parameters.
The engine ECM powers all sensors on the engine. It also powers the solenoid for the fuel injection pump,
wastegate solenoid, diagnostic connector, and electronic unit injectors.
The engine ECM supplies 5.0 ± 0.2 DC Volts to each sensor. A short in a sensor or a wiring harness will not cause
damage to the engine ECM.