2009 JAGUAR XF ECO mode

3-10
04/14/2009 NP10-V8JLR: AJ133 5.0-Liter DFI V8 Engine
Technical Training
Relays

Engine Management System

RELAYS
Main Relay
The main Engine Management System (EMS) relay is
not a main power input; it is used to initiate the power-up
and power-down routines within the ECM.
This input comes from the engine junction box (EJB).
When the ignition is turned on 12V is applied to the igni-
tion sense input. The ECM then starts its power-up rou-
tines and turns on the ECM main relay, the main power
to the ECM and its associated system components.
When the ignition is turned OFF, the ECM will maintain
its powered-up state for several seconds (or up to 20
minutes in extreme cases when cooling fans are
required) while it initiates its power-down routine and,
on completion, will turn off the ECM main relay.
The main relay is located in the EJB. The operation of
the main relay is controlled by the ECM, which provides
a ground path for the main relay coil, energizing the
relay and closing the relay contacts.
The main relay supplies battery voltage to the following
engine sensors and actuators:
• Throttle position (TP) sensor (through ECM)
• Fuel injectors
• Ignition coils
• Coil capacitor
• CPS solenoids
• All heated oxygen sensors
• Evaporative emission (EVAP) canister purge valve
• Diagnostic Monitoring of Tank Leakage (DMTL)
Failure Modes
• Relay drive open circuit
• Short circuit to battery voltage or ground
• Component failure
Failure Symptoms
• Engine will not start
Starter Relay
The starter motor relay is located in the EJB. Operation
of the starter motor relay is controlled by the ECM,
which provides a ground path for the relay coil, energiz-
ing the relay and closing the relay contacts. When the
relay contacts are closed, battery voltage is supplied,
through the starter motor relay, to the starter module
solenoid coil.
The starter solenoid is energized and connects the starter
motor with a direct battery feed to operate the starter
motor.
Once the engine has started, the ECM removes the
starter motor relay ground, opening the relay contacts
and terminating the battery feed to the starter solenoid,
which in turn stops the operation of the starter motor.
NOTE:
Diagnose using Jaguar Land Rover approved
diagnostic equipment.

Technical Training
NP10-V8JLR: AJ133 5.0-Liter DFI V8 Engine 04/14/2009
3-13
Engine Management System

Camshaft Position Sensor

CAMSHAFT POSITION SENSOR
The camshaft position (CMP) sensors are magneto-
resistive element (MRE) sensors, which have digital out-
put with zero speed recognition. They show a high signal
if the camshaft position target is directly in front of the
sensor, and low if the camshaft position target is not in
front of the sensor.
There are four common sensors, one per camshaft.
Failure Modes
• Sensor open circuit
• Short circuit to vehicle battery supply or ground
• Mechanical fitting and integrity of the sensor
• Camshaft wheel tolerances/camshaft end float excessive
• Camshaft and crankshaft misalignment/valve timing error
• Camshaft wheel magnetized/residual magnetism
• Speed signal correlation with crankshaft sensor input
• Incorrect air gap between camshaft and sensor
NOTE:
If both the CKP sensor and the CMP sensor fail,
the engine will stall or not start.
Failure Symptoms
• Ignition timing reverting to the base mapping, with no cylinder correction
• VCT is disabled
NP10V8096
NP10V8097
NP10V8098
43.40°43.40°43.40° 91.60°
91.60°
133.40°133.40°
91.60°
133.40°
91.60°
91.60°91.60°

Specification
Function

Pin 1 Supply
Pin 2 Ground
Pin 3 Signal
Operating voltage 4.5 to 7 V
Maximum supply current 22 mA

Technical Training
NP10-V8JLR: AJ133 5.0-Liter DFI V8 Engine 04/14/2009
3-17
Engine Management System

Mass Air Flow Sensor

MASS AIR FLOW SENSOR
Mass air flow is determined by the cooling effect of
intake air passing over a ‘hot film’ element contained
within the device. The higher the air flow the greater the
cooling effect and the lower the electrical resistance of
the ‘hot film’ element. The ECM then uses this analog
signal from the mass air flow (MAF) sensor to calculate
the air mass flowing into the engine.
The measured air mass flow is used in determining the
fuel quantity to be injected in order to maintain the sto-
ichiometric air/fuel mixture required for correct opera-
tion of the engine and exhaust catalysts. Should the
device fail, there is a software backup strategy that will
be activated once a fault has been logged.
The intake air temperature (IAT) sensor is integrated into
the MAF sensor. The IAT sensor is an NTC thermistor,
meaning that the sensor resistance decreases as the sen-
sor temperature increases.
The sensor forms part of a voltage divider chain with an
additional resistor in the ECM. The voltage from this device
changes as the sensor resistance changes, thus relating the
air temperature to the voltage measured by the ECM.
Because the engine requires a twin air intake induction
system, there are two MAF sensors per vehicle.
Safety Precautions CAUTIONS:
• Component should not be dropped or han-dled roughly.
• Ensure that no contamination enters the device.
• Some terminals in MAF and connector are gold-plated for corrosion resistance – DO
NOT probe.
Failure Modes
• Sensor open circuit
• Short circuit to battery voltage or ground
• Contaminated/damaged sensor element
• Air leak after MAF sensor
• Intake air restricted
• Resistance in the harness, causing signal offset
• Damaged sensor element
Failure Symptoms
• During driving the engine rpm might dip (before recovering)
• Difficulty in starting or start/stall
• Poor throttle response/engine performance
• Emissions incorrect
• Lambda control and idle speed control halted
• MAF signal offset
NP10V8102
SpecificationFunction
Supply Voltage 8 – 14V
(rated supply voltage: 14V)
Pin A Output (Vg)
Pin B Ground for Output (Vg)
Pin C Power Source
Pin D IAT Sensor Ground
Pin E IAT Sensor Output