1998 JAGUAR X308 relay

E
ngine Management System Components
Electronic Throt
tle
The
electronic throttle assembly, in resp
onse to signals from both the driver and the ECM, adjusts idle speed, sets the
throttle valve to the position requested by the driver's accelerator / throttle pedal, cruise and traction control, power
limitation and catalyst warm-up.
Mass
Air Flow Meter
The sensor i
s located in the air flow mete
r assembly and outputs an analogue voltag e to the ECM. This sensor measures air
flow into the engine inlet system and is calibrated to measure kg / hour.
In
take Air Temperature
Th
e intake air temperature sensor is loca
ted in the air flow meter assembly and outputs an analogue voltage to the ECM.
The ECM will substitute a default value eq ual to 50°C should this sensor fail.
Fuel Injectors
The eigh
t bottom fed fuel injectors are located in the fuel rails. Th
e fuel injectors are electromagnetic solenoid valves
controlled by the ECM. The pulse time for the injector combined with the fuel pr essure determines the volume of fuel
injected to the manifold.
Fue
l Delivery
The fu
el pump provides fuel to the fuel rail where the circulat
ing pressure is controlled by a pressure regulator valve; excess
fuel is returned to the fuel tank.
The pressure regulator valve is controlled by manifold depression so that fuel delivery pressure is maintained at
approximately 3 bar above manifold pressure.
Fuel Pump
Relay
The ECM controls thi

s component for normal
engine running. The security system may disable this relay via communication
with the ECM.
Fuel Lev
el Sensing
The tank fuel

is measured by the fuel le
vel sensor . This signal is used by the ECM as an in put to certain diagnostics.
Eva
porative Valve
Excess vapour

formed in the fuel tank is
absorbed into the evaporative emission pu rge control canister. While the engine is
running, the fuel absorbed in the canister is gradually purged back into the engine. The rate of purging is governed by
engine operating conditions and vapour concentration level. Operating conditions which affect the purge rate are:
2—Purge
valve
3—Engine

torque reduction
4—E

lectronic throttle assembly
5—Coo

ling fans
6—Ignition amplifier driver
7—Engine overspeed
8—Cli

mate control compressor clutch
9—O

BDII information (J1962, CAN, ISO)

10—F
uel pump relay
11—Heat

ed oxygen sensor
12—Vari

able valve timing
13—MIL sw

itching



ECM Out
puts
It

em
Par
t Number
De
scription
1—Exhaus

t gas recirculation

Speed an
d load
Coo
l
ant temperature
Ti
me el
apsed from start up
Cl
osed l
oop fuelling
Determination of the vapour concentration is made by stepped opening of the EVAP valve and subsequent monitoring of the
fuelling correction. This function is performed prior to purging, so that at the onse t of purging the EVAP valve can be set to
the optimum position. Should the ECM be unable to determine the concentration before purging, a default value is
employed, which is then modified whilst purging is in progress.
When the purging process is operational th e ECM modifies the basic fuelling calculation to maintain the correct air / fuel
ratio.
Purging is inhibited during fuel cut-off and stability / traction control intervention.
Coolant Temperature Sen
sor
Th
e
sensor outputs a voltage to the ECM which decreases as temperature increases.
Cooling Fans


In response to engi
ne coolant temperat
u
re and climate control system demand, the ECM will energize the cooling fans.
Climate Control Compressor
The E
C
M will allow the compressor clutch to be engaged if th
e engine temperature and load demand are normal. Should the
driver require maximum engine powe r or the coolant temperature be high, the request will be denied.
Cranking Signal

The ECM reacts to a signal fr
om th
e Body Processor Module (BPM) when the starter motor relay is energi
zed. This signal is
used to trigger starting, fu el and ignition strategies.
Engine Speed and Cranksh
aft Position
Engine
speed and cran
k position are moni
tored by a sensor which is mounted on the cylinder block (flywheel housing)
behind the crankshaft drive plat e. It indicates rotational speed to the ECM in the form of 12 pulses per crank revolution.
Engine speed is used for synchronization of fuel an d ignition systems, as well as other functions.
Camshaft Position
The ca
mshaft position sensor is mounted at
the rear of Bank 2 cylinder head on the inlet side and provides one signal every
720 degrees of crankshaft rotation. The signal, in conjunction with the signal from the crankshaft position sensor, indicates
to the ECM that the piston of cylinder 1A is approaching TDC on the compression stroke.
Variable Valve
Timing (Where Fitted)
By energi
si
ng a solenoid to allow the pass
age of pressurized oil on each of the inle t camshaft drives, the ECM can vary by a
single stepped amount, the relati ve timing of the inlet valves.
Ign
ition
Ignit
i
on spark is produced by
individual on-plug coil units.
There are two ignition amplifiers; module #1 drives coils 1A, 2B, 3B and 4A, whilst module #2 drives coils 1B, 2A, 3A and
4B. The ECM controls the amplifiers.

Connect
the scan tool
1
Have the DTC(s) and fr
eeze f
rame data been recorded?
Yes GO to A2
A2: CH
ECK FUSE / RELAY
Check that fuse F
12 i
s good
and that EMS control relay is
energized
1
OK ?

Yes GO to A3
No Rectify as required
A3: CH
ECK VVT COIL RESISTANCE

Me
asure the voltage between PI032/002 and ground
EM016L
1
B+ ?
Yes

GO to C5
No Inspect EM020/010 PI031 (PI032) for bent / pushed back
pins or locate and repair harness / splice PIS06.
Check fuse F12 is good and EMS control RELAY 1
energized. Test the system for normal operation.
C
5: CHECK HARNESS SHORT TO GROUND

Engi
ne Coolant Temperature Sensor (ECT) - Circuit Diagram

Intercooler Pump Relay - Circuit Diagram
T emper
ature (°C)
No
mi
nal Resistance (kOHM)
-2
015 .0
4
05.7
4
202.45
401.15
600.
584
800.3
2
1000.
184
ItemPar
t
Number
De
scrip
tion
1—Eng
i
ne Coolant Temperature (ECT) Sensor
2—Eng
i
ne to EMS Harness Connector
3—EMS Con
trol Modu
le

ItemPar
t Number
De
scription
1—Lug

gage compartment fuse box
2—I

ntercooler pump relay
3—I

ntercooler pump
4—Electr

onic control module

Pinpoint test
A: P0116, P0125
Connector
loose or corroded
*
D
TC P0118 ECT circuit high input
Sensor short
Harness open circui

t
Harness short
Connector loose or corroded
*
*
*
*
GO to Pinpoint

Test C
*
D
TC P1474 Intercooler coolant pump relay malfunction
Intercooler pump relay
failure
Intercooler pump relay to ECM drive circuit
fault Intercooler pump relay coil ground circuit
fault Harness fault
Connector loose or corroded
Connector pins(s) bent or tracking between
connections ECM power supply fault
*
*
*
*
*
*
*
GO to Pinpoint

Test D
*
P
INPOINT TEST A : P0116, P0125
T
EST CONDITIONS
D
ETAILS/RESULTS/ACTIONS
A1

: RETRIEVE DTCS
•

NOTE: Battery and or ECM disconnection prior to scanning wi
ll erase all data, ensure that the correct DTC is present.
Conne
ct the scan tool
1
Have the DTC(s) and fr

eeze
frame data been recorded?
Yes GO to A2
A2: ENGINE
COOLANT SYSTEM CHECK
•

NOTE: Do not use the instrument display, if th
e ECT has failed this will not operate correctly.
Chec
k engine temperature rise using a thermocouple or
similar device.
1
Engine
temperature increasing?
Yes GO to A3
No Check coolant level
Check coolant for contamination
Check/test thermostat

Conne
ct the scan tool
1
Have the DTC(s) and fr

eeze
frame data been recorded?
Yes GO to D2
D
2: CHECK FUSE
•

NOTE: See further steps for poss
ible cause of fuse failure.
Chec
k fuse F2 integrity (located in the engine
management fuse box).
1
OK
?
Yes GO to D3
No Renew fuse and test the syst em for normal operation.
D3: C
HECK RELAY SOCKET SUPPLY VOLTAGE
•

NOTE: Do not replace relay.