Cooling fan relay JAGUAR XF 2009 1.G AJ133 5.0L Engine Manual

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04/14/2009 NP10-V8JLR: AJ133 5.0-Liter DFI V8 Engine
Technical Training
Engine Control Module

Engine Management System

ENGINE CONTROL MODULE
The ECM is supplied with battery voltage from a 5A fuse and an ignition supply from the ECM relays through\
a 15A
fuse, both located in the CJB. A regulator located within the ECM supplies a 5V current to internal compone\
nts such
as the microprocessor unit. Other components or functions requiring full\
battery voltage are controlled by external
relays or internal switching modules.
The microprocessor within the ECM receives signals from different components and control modules and uses a pro-
gram within the ECM software to interpret the signal information and issue signals which relate t\
o how the engine
components and functions should be controlled. The ECM communicates with other control modules via bidirectional
Controller Area Network (CAN) communication interfaces.
The ECM uses the following inputs and outputs:
Inputs
• Camshaft position (CMP) sensor
• Crankshaft position (CKP) sensor
• Fuel rail high-pressure sensor
• Mass air flow (MAF) sensors (2)
• Knock sensors (4)
• Engine coolant temperature (ECT) sensor
• Manifold absolute pressure (MAP) sensor
• Electronic throttle position sensor
• Accelerator pedal position (APP) sensor
• Cooling fan speed
• Upstream Universal Heated Exhaust Gas Oxygen (UHEGO) sensors (2)
• Brake switch
• Speed control cancel/suspend switch
• Intake air temperature (IAT) sensor (integrated into the MAF) (2)
• Ambient air temperature (AAT) sensor
• Engine oil level and temperature sensor
• Temperature and manifold absolute pressure (TMAP) sensor (SC only)
Outputs

• Throttle Actuator
• Coil-on-plug (COP) ignition coils (8)
• Upstream Universal Heated Exhaust Gas Oxygen (UHEGO) sensors (2)
• Downstream Heated Oxygen Sensors (HO2S) (2)
• Direct injection fuel injectors (8)
• Variable camshaft timing (VCT) solenoids (4)
• Camshaft profile switching (CPS) solenoids (2)
• Intake manifold tuning solenoid
• Carbon canister purge valve
• Fuel pump relay
• Starter relay
• A/C condenser fan relay
• ECM main relay viscous fan control
• Generator control
• Air flap solenoid (SC only)
• Pump control diagnostics
• Diagnostic Monitoring of Tank Leakage (DMTL)

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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.