Installation Manual

Electrical & Electronic Application And Installation Manual
Production Release Version 1.0
Page 12
It should be noted that in many cases a fault on any of these sensors,
solenoids or switches will cause the engine to derate, or enter a limp home
state due to their emissions critical nature.
2.1.3 Engine Speed
The engine is fitted with two Hall effect speed sensors. The first is mounted
on the engine to measure the crank speed and position and the other is used
to measure the cam shaft speed, position and engine cycle. The engine uses
the crank speed signal during normal engine operation as this signal is more
accurate at higher speeds. If the crank shaft speed signal is lost during
engine running then the engine will enter a derate condition, however if the
engine is cranking the engine will start but be limited to a programmed derate.
The cam shaft speed sensor is used to calculate the engine cycle during
engine starting and for limp home operation. For this reason if the camshaft
speed timing sensor signal is lost the engine will not start, but if the engine is
running a fault code will be raised and the engine will continue to run normally.
2.1.4 NRS (NOx Reduction System)
The NOx reduction system is made up of the following components;
• NRS Intake Absolute Pressure Sensor
• NRS Differential Pressure Sensor
• NRS Temperature Sensor
• NRS metering Valve
Both the temperature and pressure sensor measurements are required by the
engine control system to control NRS metering valve. The metering valve
controls the mass air flow through the NOx reduction system cooler by means
of a DC motor and a position sensor.
This part of the engine control system is emissions critical and for this reason
the engine may apply a derate if any of these components enter a fault
condition.
2.1.5 Core Engine System
There are a number of core engine operation sensors that are used to
determine how the engine control system should respond to various
conditions. These components include the barometric sensor, coolant
temperature sensor and the oil pressure sensor.
The barometric sensor is located near the ECM. The sensor is used to
determine atmospheric (barometric) pressure. The atmospheric pressure is
used to determine the atmospheric related fuel limits (if any) e.g. at high
altitude fuel may be limited during cranking to prevent turbo overspeed.
The coolant temperature sensor measurement is used as an input to the cold
start strategy. The sensor reading is also used to determine fuel limits and
injection timing at various temperatures to control engine emissions.