Jaguar XJ (X350). Manual — part 847

provide optimum driver control under all conditions.

minimize evaporative emissions.

provide system diagnostics.

In addition to these functions the ECM also interfaces with other vehicle systems through the

controller area network (CAN).

Camshaft Position (CMP) Sensor

The camshaft position (CMP) sensors monitor the position of both camshafts to allow the ECM to

control the phase of the inlet camshafts relative to the position of the crankshaft.

Variable Camshaft Timing Oil Control Solenoid

The variable camshaft timing oil control solenoid is a hydraulic actuator, which advances and retards

the inlet camshaft timing, thereby altering the camshaft to crankshaft phasing for optimum engine

performance.

Intake Manifold Tuning (IMT) Valve

There are two intake manifold tuning (IMT) valves, an upper and a lower, sometimes referred to as

number one and two respectively. They are a two position (open and close) device used to create a

variable air intake system. The IMT valve positions are switched by signals from the ECM to optimize

torque across the engine's speed and load range. The upper IMT valve opens between 4,100 and

6,150 rpm while the lower IMT valve opens between 3,900 and 6,150 rpm.

Knock Sensors (KS)

The knock sensors (KS) detect combustion knock within the engine cylinders and sends a signal to the

ECM. The ECM uses this information to gradually adjust the ignition timing until the combustion

knock is eliminated.

Mass Air flow (MAF) Sensor

The mass air flow (MAF) sensor informs the ECM of the rate of air flow entering the engine by

producing a voltage which is proportional to the rate of air flow into the engine. The voltage

produced by the MAF sensor increases as the rate of air flow increases. The ECM also takes into

account the density of the air entering the air intake system so that it is possible to maintain the

required air to fuel ratio, and to compensate for variations in atmospheric pressure.

Integral to the MAF sensor is the intake air temperature sensor (IAT) which measures the

temperature of the air entering the air intake system. The ECM uses this information to compensate

for higher than normal air intake temperatures.

Fuel Rail Pressure (FRP) Sensor

The fuel rail pressure (FRP) sensor is a pressure transducer device. A vacuum pipe connects to the

intake manifold for manifold pressure. The ECM receives a voltage from the FRP sensor which is

proportional to the fuel pressure in the fuel injection supply manifold.

Throttle Position (TP) Sensor

The ECM monitors the angle of the throttle blade within the throttle housing through the throttle

position (TP) sensor. The TP sends a voltage to the ECM which is proportional to the angle of the

throttle plate. The voltage from the TP increases with the angle of the throttle plate. There are two

sensor tracks within the TP sensor.

Crankshaft Position (CKP) Sensor

The crankshaft position (CKP) sensor is an inductive pulse generator, which scans protrusions on a

pulse ring fitted to the front of the crankshaft to inform the ECM of the crankshaft's position and

speed. The CKP sensor produces an alternating voltage. The frequency of this voltage increases

proportional to engine speed.

Engine Coolant Temperature (ECT) Sensor

The engine coolant temperature (ECT) sensor is a thermistor type sensor that provides an input

signal to the ECM which is proportional to the engine coolant temperature. The ECT sensor is a

negative temperature coefficient (NTC) sensor and its resistance decreases with a proportional

increase in engine coolant temperature.

Oil Temperature Sensor

The oil temperature sensor is a thermistor type sensor that provides an input signal to the ECM

which is proportional to the engine oil temperature.

Oil Pressure Switch

The oil pressure switch is connected to the instrument cluster and is not directly part of the

electronic engine control system.

Heated Oxygen Sensor (HO2S)

The heated oxygen sensor (HO2S) is a linear characteristic type sensor, fitted forward of the exhaust

system's catalytic converter. The ECM uses this as it's primary sensor to measure the oxygen content

of the exhaust gasses within the exhaust system to provide closed-loop fuelling control.

Catalyst Monitor Sensor

The catalyst monitor sensor is a non-linear characteristic type sensor fitted to the exhaust system's

catalytic converter. The ECM uses this as it's secondary sensor to measure the oxygen content of the

exhaust gasses within the exhaust after they have passed through the catalytic converter. As well as

providing additional closed-loop fuelling control the ECM uses this information to determine the

efficiency of the catalytic converter.

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Diagnosis and testing

Electronic Engine Controls - VIN Range:
G00442->G45703

Inspection and Verification

1 . Verify the customer concern.

2 . Confirm which, if any, warning lights and/or messages were displayed on the instrument cluster.

NOTE:

If any warning lights and/or messages were displayed when the fault occurred, refer to the

driver information table for Diagnostic Trouble Codes (DTCs) associated with the display, then to

the DTC index table for possible sources and actions. Some warnings will appear to clear when

the ignition is cycled. This is often because the warning has flagged as a result of one of the

vehicle's on-board diagnostic routines having run to detect the fault. If the same routine is not

run when the ignition is switched ON, the warning will not reflag until the routine does run. See

the DTC summaries for drive cycle routines.

3 . Visually inspect for obvious signs of mechanical or electrical damage.

Visual Inspection Chart

Mechanical

Electrical

Engine oil level

Cooling system coolant level

Fuel level

Fuel contamination/grade/quality

Throttle body

Poly-vee belt

Fuses

Wiring harness

Electrical connector(s)

Sensor

Electronic Engine Controls - VIN Range:
G45704->G99999

Overview

There are changes to the engine management system (EMS) for 2006 my, the most obvious of which

will be the change to 7-digit diagnostic trouble codes (DTCs) from the familiar 5-digit, plus the

addition of secondary air injection, changes to evaporative emissions and exhaust gas recirculation to

comply with stage four emissions requirements.

For more information on these systems,

Engine Emission Control - VIN Range: G45704->G99999

Evaporative Emissions - VIN Range: G45704->G99999

Inspection and Verification

1 . Verify the customer concern.

2 . Visually inspect for obvious signs of mechanical or electrical damage.

Visual Inspection Chart

Mechanical

Electrical

Engine oil level and condition

Cooling system coolant level

Fuel level

Fuel contamination/grade/quality

Throttle body

Poly-vee belt

Air cleaner condition

Fuses

Wiring harness

Electrical connector(s)

Sensor(s)

Engine control module (ECM)

Transmission control module (TCM)

1 . Verify the following systems are working correctly:

Air intake system

Cooling system

Charging system

Fuel charging system

Ignition system

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