Land Rover Defender 1999 2002my Workshop Supplement Body Repair 3rd Edition Rover Manual

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DESCRIPTION AND OPERATION SENSOR - AMBIENT AIR PRESSURE AND
TEMPERATURE (AAP)
The AAP sensor is located in the top of the air filter housing. It provides a voltage signal relative to ambient air
pressure to the ECM. The AAP sensor works on the piezo crystal principal. Piezo crystals are pressure sensitive
and will oscillate in accordance to changes in air pressure. The AAP sensor produces a voltage between 0 and 5
volts proportional to the pressure level of the air in the air...

ENGINE MANAGEMENT SYSTEM
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DESCRIPTION AND OPERATION SENSOR - MANIFOLD ABSOLUTE PRESSURE
(MAP) / INLET AIR TEMPERATURE (IAT)
The MAP/IAT sensors are combined in one unit located in the inlet manifold. It provides pressure and temperature
information about the air in the inlet manifold to the ECM. The ECM compares the voltage signal to stored values
and compensates fuel delivery as necessary. The ECM uses the signal from the MAP/IAT sensor for the following
functions:
To calculate the delivered fuel...

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DESCRIPTION AND OPERATION The MAP/IAT sensor can fail, or supply an incorrect signal if one or more of the following occur:
Sensor open circuit.
Short circuit to vehicle supply.
Short circuit to vehicle earth.
Contaminated sensor element.
Damaged sensor element.
Resistance in wiring harness.
In the event of a MAP/IAT sensor failure any of the following symptoms may be observed:
If the MAP sensor fails manifold pressure is set to a pre-determined default value and the...

ENGINE MANAGEMENT SYSTEM
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DESCRIPTION AND OPERATION SENSOR - ENGINE COOLANT TEMPERATURE
(ECT)
The ECT sensor is located in the coolant outlet elbow on top of the engine. It provides the ECM with engine
coolant temperature information. The ECM uses this information for the following functions:
Fuelling calculations.
Temperature gauge.
To limit engine operation if coolant temperature is to high.
Cooling fan operation.
Glow plug operating time.
The ECT works as an NTC sensor. As temperature rises,...

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DESCRIPTION AND OPERATION SENSOR - CRANKSHAFT SPEED AND
POSITION (CKP)
The CKP sensor is located in the transmission housing with its tip adjacent to the outer circumference of the
flywheel. The CKP sensor works on the variable reluctance principal, which sends a signal back to the ECM in the
form of an ac voltage.
The ECM uses the signal from the CKP sensor for the following functions.
To calculate engine speed.
To determine engine crank position.
To determine fuel...

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DESCRIPTION AND OPERATION Voltage generation from the CKP sensor is relative to engine speed. The values from a good CKP sensor are as
follows:
2 to 3 volts with engine cranking.
Rising to 6 to 6.5 volts from 1000 rev/min upwards.
The above readings are dependent upon the correct air gap between the tip of the CKP sensor and the passing
teeth of the reluctor ring.
The CKP sensor can fail or supply an incorrect signal if one or more of the following occurs:
Sensor assembly...

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DESCRIPTION AND OPERATION SENSOR - THROTTLE POSITION (TP)
UP TO VIN 607224
The TP sensor is located on the throttle pedal assembly. It detects throttle pedal movement and position. It uses
two position sensors to provide the ECM with the exact throttle pedal position. As the pedal operates, the voltage
of one position sensor increases as the other decreases.
Input / Output
The ECM (C0658-14) provides a 5 volt reference feed to both sensors (C0787-B & C0787-J) on white/purple...

ENGINE MANAGEMENT SYSTEM
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DESCRIPTION AND OPERATION SENSOR - THROTTLE POSITION (TP)
FROM VIN 607225
Defender vehicles from VIN 607225 use three track thick film potentiometers. No idle speed sender switch is used
on this type of sensor because the ECM can compare the two or three sets of signals to implement idle speed
control and over-run fuel shut-off. The two potentiometers are known as track 1 and 2 potentiometers. The track 3
potentiometer on later models is used to improve the resolution of the...

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DESCRIPTION AND OPERATION On Defender models, at wide open throttle, track 2 returns a signal of 0.28V and track 1 returns a signal of 4.7V to
the ECM. The ECM calculates the sum of these two figures which totals 5.0V.
The ECM uses this strategy to error check the TP sensor signal and ensure that the requested throttle position is
applied. The third potentiometer track measures the tolerance of tracks 1 and 2 and provides an improved
functionality check of the pedal angle....

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DESCRIPTION AND OPERATION This page is intentionally left blank