Jaguar XJ (X350). Manual — part 744

Description and operation

Engine Ignition

Component Locations

Item

Part Number

Description

1

-

Ignition coil-on-plug

2

-

Ignition coil-on-plug retaining bolt

3

-

Spark plug

The right-hand cylinders are numbered 5,3,1 and the left-hand cylinders are numbered 6,4,2 when

viewed from the rear of the engine.

The ignition system consists of an ignition coil located on each individual cylinder and each individual

spark plug. The ignition timing can now be adjusted more rapidly and independently.

The crankshaft position sensor signal is the basis for ignition timing calculations. The alternating

voltage signal from the crankshaft position sensor is converted by the engine control module (ECM).

This digital signal is then used to position the closing time of the primary circuit of the ignition coil.

The effective range for ignition timing control is increased to the fact that there are no rotating parts.

On the basis of engine speed and load inputs, the powertrain control module determines the ignition

timing. This function also takes other inputs into consideration such as engine temperature, throttle

position, knock control, cam position, traction control and electronic transmission control inputs.

This ignition system enables the customer to drive the vehicle home if a coil or coil wiring failure

occurs. In the event of a wiring failure between the powertrain control module and the coil, the coil

will fail instead of the coil fuse blowing, which will allow the remaining coils to continue to function

and the engine to limp home.

Diagnosis and testing

Engine Ignition - 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 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(s)

Engine control module (ECM)

Transmission control module

1 . Verify the following systems are working correctly:

Air intake system

Cooling system

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Charging system

Fuel system

2 . If an obvious cause for an observed or reported concern is found, correct the cause (if possible)

before proceeding to the next step.

3 . Where the Jaguar approved diagnostic system is available, complete the S93 report before

clearing any or all fault codes from the vehicle.

NOTE:

If a DTC cannot be cleared, then there is a permanent fault present that flags again as soon as it

is cleared. (The exception to this is P1260, which will only clear following an ignition OFF/ON

cycle after rectification).

4 . If the cause is not visually evident and the Jaguar approved diagnostic system is not available, use

a fault code reader to retrieve the fault codes before proceeding to the Diagnostic Trouble Code

(DTC) Index Chart, or the Symptom Chart if no DTCs are set.

5 . Using the Jaguar approved diagnostic system where available, and a scan tool where not, check

the freeze frame data for information on the conditions applicable when the fault was flagged. The

format of this will vary, depending on the tool used, but can provide information useful to the

technician in diagnosing the fault.

CAUTION: When probing connectors to take measurements in the course of the pinpoint

tests, use the adaptor kit, part number 3548-1358-00.

NOTE:

When performing electrical voltage or resistance tests, always use a digital multimeter (DMM)

accurate to 3 decimal places, and with an up-to-date calibration certificate. When testing

resistance, always take the resistance of the DMM leads into account.

NOTE:

Check and rectify basic faults before beginning diagnostic routines involving pinpoint tests.

Symptom

Possible source

Action

Engine cranks, but does

Engine breather system

disconnected/restricte

Check engine breather system, <<303-08>>

not fire

d

Ignition system

Fuel system

Harness

CKP sensor

ECM fault

For ignition system tests, refer to pinpoint

tests in this section. Check fuel pressure.

For CKP tests, <<303-14>> Contact dealer

technical support for advice on possible

ECM failure.

Engine cranks and fires,

but will not start

Purge valve

Fuel pump

Engine coolant

temperature (ECT)
sensor

Spark plugs

HT short to ground

(tracking) check rubber
boots for
cracks/damage

Ignition coil failure(s)

Harness

For evaporative emissions components,

<<303-13>> Check fuel pressure, <<310-

01>> For ECT sensor tests, <<303-14>> For

ignition coil circuit tests, GO to Pinpoint

Test G290075p1.

. For ignition coil information,

Ignition Coil-On-Plug LH (18.20.44) and

Ignition Coil-On-Plug RH (18.20.43)

Difficult to start cold

Check coolant anti-freeze

content

Battery

CKP sensor

EGR valve stuck open

Fuel pump

Engine coolant

temperature (ECT)
sensor

Purge valve

For battery information, <<414-01>> For

CKP sensor tests, <<303-14>> For EGR

system information, <<303-08>> Check fuel

pressure. For ECT sensor tests, <<303-14>>

For evaporative emissions components,

<<303-13>>

Difficult to start hot

Injector leak

Engine fuel temperature

For fuel injectors, <<303-04>> For EFT

sensor, IAT sensor and MAF sensor tests,

<<303-14>> For evaporative emissions

components, <<303-13>> Check fuel

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