LR3/Disco 3
The Inlet Air Temperature (IAT) sensor is integrated into the Mass Air Flow meter. It is a temperature dependent resistor
(thermistor), i.e. the resistance of the sensor varies with temperature. This thermistor is a negative temperature coefficient
(NTC) type element meaning that the sensor resistance decreases as the sensor temperature increases. The sensor
forms part of a voltage divider chain with an additional resistor in the ECM. The voltage from this network changes as the
sensor resistance changes, thus relating the air temperature to the voltage measured by the ECM.
The fixed default value for air temperature is 35°C
MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR
The MAP sensor provides a voltage proportional to the absolute pressure in the intake manifold.
This signal allows the load on the engine to be calculated and used within the internal calculations of the ECM.
The sensor is located in the EGR valve at the front LH side of the engine.
DIFFERENTIAL PRESSURE FEEDBACK-ELECTRONIC/MANIFOLD ABSOLUTE
PRESSURE SENSOR (DPFE/MAP)
This pressure transducer monitors the pressure differential on either side of an orifice in the EGR system flow path and
transmits that information to the ECM. The pressure drop measured across this orifice is used to estimate the flow rate of
recirculated exhaust gas. An Electronic Vacuum Regulator (EVR) is used to control the vacuum signal to the EGR valve
based on the electrical signal from the ECM. The ECM monitors the EGR level based on the feedback from the
DPFE/MAP transducer, which creates a closed loop system.
EXHAUST GAS RETICULATION VALVE (EGR)
The EGR (exhaust gas recirculation) Valve is a PWM controlled valve that allows burned exhaust gas to be recirculated
back into the engine. Since exhaust gas has much less oxygen than air, it is basically inert. It takes the place of air in the
cylinder and reduces combustion temperature. As the combustion temperature is reduced, so are the oxides of nitrogen
(NOx) emissions.
CRUISE CONTROL SWITCHES
Item Part Number
Description
