1998 JAGUAR X308 AF sensors

It
em
Par
t Number
De
scription
1—MAF

assembly
2—MAF s

ensor
3—IAT se

nsor
4—Engi

ne to vehicle harness connector
5—EMS fuse box


6—Engine

control module (ECM)
7—Charge air cool

er -
IAT sensor (superchar
ged engin
es only)

MAF
and IAT Sensors

It e
m
De
scr
iption
1Engine
c
ontrol
module (ECM)
2Do
wnstream oxygen sensor (A)
3Upstream heated ox
ygen sensor
(A)
4D
o
wnstream oxygen sensor (B)
5Upstream heated ox
ygen sensor (B)
6Engine
management fuse box
Ox
yg
en Sensors

Driver Information
Chart
•

NOTE: Use this table to identify DTCs associated with the me
ssage center display, then refer to the DTC index for possible
sources and actions.
• NOTE: For definitions of Default Modes, see the foot of this table.
Poor
dr iveabilityEngine h e
sitates/poor
acceleration
Fue l
pump
Exhaus
t gas
recirculation
(EGR)
Air leakage Stop lamp swi t
ch
Throttl
e
sensors
Throttl
e
motor
Spark
plugs
fouled
Check f
o
r water ingress
into spark plug wells
Ignition coil fail
ure(s)
HT sh
o
rt to ground
(tracking) check rubber
boots for cracks/damage
ECM failu r
e
Check f
u
el pressure. For EGR information,
REFER to Section 303
-08 En gin
e Emission
Control.
F or i
ntake system information,
REFER to Section 303
-1 2
Intake Air Distribution

and F
ilt
ering
.
F or stop l
amp switch in
formation, refer to the
wiring diagrams. For throttle position sensor
tests,GO to Pinpoint Test D.
. Fo
r throttle motor
control circuit tests,GO to Pinpoint Test T.
. For
igni t
ion system,
REFER to Section 303
-07 En
gine Ignition
.
F or ECM
circuit tests,GO to Pinpoint Test
AD.
.
Engine backfiresFuel
pump
Air leakage MAF se

nsor
HO2 sensors
Spark plugs Check fo
r water ingress
into spark plug wells
HT sh o
rt to ground
(tracking) check rubber
boots for cracks/damage
Ignition coil fail
ure(s)
Chec
k fu
el pressure. For intake system
information,
REFER to Section 303
-12
Intake Air Distribution

and Filt
ering
.
F or MAF sensor ci
rcuit test
s,GO to Pinpoint Test
A.
. F or HO2 sensor
circui
t tests, check for DTC
indicating which sensor and follow indicated pinpoint test. For ignition system,
REFER to Section 303
-07 En
gine Ignition
.
Engine
s
urges
Air leakage
Fuel
pump
Stop lamp swit

ch
MAF s
e
nsor
Harness Throttl
e
sensors
Throttl
e
motor
Spark plugs
Check fo
r water ingress
into spark plug wells
HT sh o
rt to ground
(tracking) check rubber
boots for cracks/damage
ECM failu r
e
Fo
r
intake system,
REFER to Section 303
-1 2
Intake Air Distribution

and Filt
ering
.
Check fu
el pressure. For
stop lamp information,
refer to the wiring diagrams. For MAF sensor tests,GO to Pinpoint Test A.
. Fo
r throttle
position sensor tests,GO to Pinpoint Test D.
,
a n
dGO to Pinpoint Test
K.
. Fo
r throttle motor
circuit tests,GO to Pinpoint Test T.
. For ig
nition
system,
REFER to Section 303
-07 En
gine Ignition
.
F or ECM
circuit tests,GO to Pinpoint Test
AD.
.
Engine detonates/k
nocks
Fue
l
pump
HO2 sensors
Air leakage Blocked part-load breather
(s
ervice action S474)
Mass ai
r fl
ow (MAF) sensor
Chec
k fu
el pressure. Fo
r HO2 sensor circuit
tests, check for DTC indicating which sensor and
follow indicated pinpoint test. For intake system
information,
REFER to Section 303
-1 2
Intake Air Distribution

and Filt
ering
.
Check service action S474
. For MAF sensor
tests,GO to Pinpoint Test A.
.
No t
hrottle response
Traction contr
o
l invoked
Throttl
e
sensors
Throttl
e
motor
Fo
r th
rottle position sensor tests,GO to Pinpoint
Test D.
, andG O to Pinpoint
Test
K.
. Fo
r throttle

motor circuit tests,GO to Pinpoint Test T.
.
Cru i
se control inhibited or

disabled
Cru i
se control switch
Throttle

sensors
Stop lamp swit

ch
For cru
i
se control switches,
REFER to Section 310
-03
Speed Control
.
For th
rottle position sensor tests,GO to Pinpoint
Test D.
, andG O to Pinpoint
Test
K.
. For s t
op
light switch information, refer to the wiring diagrams.

H02S harness wiri
ng fault
E
x
haust leak (before catalyst)
ECM receivi
n
g incorrect signal from

one or more of the following
sensors - ECT, MAF, IAT, TP
pr essure regulator,
REF
ER to Section 303
-04
Fu
el
Charging and Con
t
rols
.
Chec k the
fuel pressure. Check the
exhaust system for leaks,
REFER to Section 309
-00 Ex
haust
Sy
ste
m
.
R e
fer to pinpoint tests for sensors
listed.
P0172Right -
hand cylinders combustion
too rich
Engine m
isfire
Bl
ocked air
filter
F
u
el system return blockage
Leak
i
ng fuel injector(s)
F
u
el pressure regulator failure
(high fuel pressure)
ECM receivi n
g incorrect signal from

one or more of the following
sensors - ECT, MAF, IAT, TP
Chec k for 'en
gine misfire detected'
DTCs. Check the air filter element,
REFER to Section 303
-1 2
Intake Air
Distribu
tion and Filterin
g
.
Chec k the
fuel lines,
REFER to Section 310
-01 Fu
el Tank
and Lines.
Chec k the
fuel injectors and fuel
pressure regulator,
REFER to Section 303
-04 Fu
el
Charging and Con
t
rols
.
R e
fer to pinpoint tests for sensors
listed.
P0174L e
ft-hand cylinders combustion
too lean
Air in
take leak between MAF senso
r and th
ro
ttle
F
u
el filter system blockage
F
u
el injector blockage
F
u
el pressure regulator failure (low

fuel pressure)
Low fu
el pump output
H0
2S harness wiri
ng fault
E
x
haust leak (before catalyst)
ECM receivi
n
g incorrect signal from

one or more of the following
sensors - ECT, MAF, IAT, TP
Check the ai r intak
e system for leaks,

REFER to Section 303
-1 2
Intake Air
Distribu
tion and Filterin
g
.
Check the fuel fi lter,
REF
ER to Section 310
-01
Fu
el Tank
and Lines.
Chec k the
fuel injectors and fuel
pressure regulator,
REFER to Section 303
-04 Fu
el
Charging and Con
t
rols
.
Chec k the
fuel pressure. For HO2S
circuit tests,GO to Pinpoint Test H.
,
a n
dGO to Pinpoint Test
I.
. Check
the
exhaust system for leaks,
REFER to Section 309
-00 Ex
haust
Sy
ste
m
.
R e
fer to pinpoint tests for sensors
listed.
P0175L e
ft-hand cylinders combustion
too rich
Engine m
isfire
Bl
ocked air
filter
F
u
el system return blockage
Leak
i
ng fuel injector(s)
F
u
el pressure regulator failure
(high fuel pressure)
ECM receivi n
g incorrect signal from

one or more of the following
sensors - ECT, MAF, IAT, TP
Chec k for 'en
gine misfire detected'
DTCs. Check air filter element,
REFER to Section 303
-1 2
Intake Air
Distribu
tion and Filterin
g
.
Chec k the
fuel lines,
REFER to Section 310
-01 Fu
el Tank
and Lines.
Chec k the
fuel injectors and fuel
pressure regulator,
REFER to Section 303
-04 Fu
el
Charging and Cont

rols
.
Re
fer to pinpoint tests for sensors
listed.
P0201 Fu
el injector circuit malfunction,
cyl 1
Injector discon n
ected
Inject
or wir
ing open or short circuit

Injector fail
ure
F
o
r fuel injector
circuit tests,
REFER to Section 303
-04 Fu
el
Charging and Con
t
rols
. P0202F
u
el injector circuit malfunction,
cyl 3
P0203F u
el injector circuit malfunction,
cyl 5
P0204F u
el injector circuit malfunction,
cyl 7
P0205F u
el injector circuit malfunction,
cyl 2
P0206F u
el injector circuit malfunction,
cyl 4
P0207F u
el injector circuit malfunction,
cyl 6
P0208F u
el injector circuit malfunction,

op
en circuit
ECM ground circuit faul
t (relay coil

drive)
P1235Vacuu m
switching valve (VSV) 1
circuit range/ performance
(mechanical guard position)
Vac u
um leak/blockage between the

throttle elbow and the throttle
vacuum actuator
Vacuu m
actuator failure
Mechanica
l
guard actuator
seized/spring broken
Carr y out mechanical checks
for
vacuum leak/blockag e, failed vacuum
actuator, and broken /siezed actuator
spring.
P1236Vacuu m
switching valve (VSV) 1
(vacuum) circuit failure
VSV 1 disconne cted

VSV 1 to ECM drive circu
i
t high
resistance, open circuit or short
circuit
VSV 1 powe r supply open
circuit
VSV 1 failu
r
e
For VSV tests,

REF
ER to Section 310
-03
Sp
eed
Control.
P1237Vacuu
m
switching valve (VSV) 2
(atmosphere) circuit failure
VSV 2 disconne cted

VSV 2 to ECM drive circu
i
t high
resistance, open circuit or short
circuit
VSV 2 power supply open
circuit
VSV 2 failu
r
e
For VSV tests,

REF
ER to Section 310
-03
Sp
eed
Control.
P1238Vacuu
m
switching valve (VSV) 3
(release) circuit failure
VSV 3 disconne cted

VSV 3 to ECM drive circu
i
t high
resistance, open circuit or short
circuit
VSV 3 powe r supply open
circuit
VSV 3 failu
r
e
For VSV tests,

REF
ER to Section 310
-03
Sp
eed
Control.
P1240Sensor r
e
fere
nce voltage
malfunction (throttle sensors, fuel
tank pressure se nsor) (ECM pins
EM10-21; EM11-8)
ECM t o
sensors reference voltage
short circuit to ground, short circuit
to high voltage, op en circuit, high
resistance
TP sensor , pedal position and
mechan
ical guard sensor(s), fuel
tank pressure sens or failure(s)
Fo
r sensor reference voltage circuit
tests,GO to Pinpoint Test V.
.
P1241Sensor re
ferenc
e voltage low
(throttle sensors, fuel tank
pressure sensor) (ECM pins EM10-
21; EM11-8)
ECM t o
sensors reference voltage
short circuit to ground
TP sensor , APP
and mechanical
guard sensor(s), fuel tank pressure
sensor failure(s)
F o
r sensor reference voltage circuit
tests,GO to Pinpoint Test V.
.
P1242Sensor re
ferenc
e voltage high
(throttle sensors, fuel tank
pressure sensor) (ECM pins EM10-
21; EM11-8)
ECM t o
sensors reference voltage
circuit open circuit, high resistance,
short circuit to high voltage
TP sensor , APP
and mechanical
guard sensor(s), fuel tank pressure
sensor failure(s)
F o
r sensor reference voltage circuit
tests,GO to Pinpoint Test V.
.
P1243Sensor re
ference ground
malfunction (throttle sensors, fuel
tank pressure sensor, ECT sensor,
IAT sensor, IAT sensor 2) (ECM
pins EM10-20; EM11-12)
ECM t o
sensors reference ground
circuit open circuit, high resistance
Throttle sensors, fuel
tank pressure

sensor, ECT sensor, IAT sensor,
IAT sensor 2 failures
F o
r sensor reference ground circuit
tests,GO to Pinpoint Test W.
.
P1245Engine crank signal low voltage Starter relay coi
l to ECM/BPM
circuit open circuit
For en gin
e crank circuit tests,GO to
Pinpoint Test X.
.
P1246Engine crank signal high voltage Starter relay coi
l to ECM/BPM
circuit short circuit to B+ voltage
B P
M failure
For en
gin
e crank circuit tests,GO to
Pinpoint Test X.
.
P1250Engine load
malfunction
Air in
take leak
Engine breath

er leak
TP sens

or circuit fault (DTC P0121)

Throttle
valve spring failure
Check air i
ntake system for leaks,
REFER to Section 303
-12
Intake Air
Distribution and Filterin

g
.
Check engi
ne breather system for
leaks,
REFER to Section 303
-08 En
gine
Emissi
on Control.
Se e
pinpoint test for P0121. For
throttle body information,
REFER to Section 303
-04 Fu
el
Charging and Con
t
rols
.
P1251Thr
o
ttle position malfunction
(engine off)
TP sensor to ECM wiri
ng open
circuit or high resistance
F o
r TP sensor circ
uit tests,GO to
Pinpoint Test D.
, andGO to Pinpoint

Yes
R
EPAIR the high resistance circui
t. For additional information, refer to the wiring diagrams. CLEAR
the DTC. TEST the system for normal operation.
No GO to U2
.
U2: CHECK T H
E MECHANICAL GUARD SENSE
CIRCUIT FOR SHORT TO HIGH VOLTAGE
Re
connect the battery negative terminal.
1
Turn the ignition swi
t
ch to the ON
position.
2
Measure t
he voltage between PI42, pin 01 (BY) and GROUND.
3
Is the volt

age greater than 10 volts?
Yes REPAIR the short circuit. For addi tional information, refer to the wiring diagrams. CLEAR the DTC.
TEST the system for normal operation.
No GO to U3
.
U3: CHECK T H
E MECHANICAL GUARD SE
NSE CIRCUIT FOR SHORT TO GROUND
Turn the ignition swit
ch to the OFF
position.
1
Measure t
he resistance between PI42, pin 01 (BY) and GROUND.
2
Is
t
he resistance less than 10,000 ohms?
Yes REPAIR the short circuit. For addi tional information, refer to the wiring diagrams. CLEAR the DTC.
TEST the system for normal operation.
No GO to U4
.
U4: CHECK THE MEC H
ANICAL GUARD SENSOR POWER SUPPLY CIRCUIT
Re
conn
ect the ECM electrical connector, EM11.
1
Turn the ignition swi
t
ch to the ON
position.
2
Measure t
he voltage between PI42, pin 04 (UW) and GROUND.
3
Is th
e volt
age less than 5 volts?
Yes
REPAIR the power supply circuit. This circuit includ es the ECM. For additional information, refer to
the wiring diagrams. CLEAR the DTC. TE ST the system for normal operation.
No INSTALL a new mechanical guard sensor. CLEAR the DTC. TEST the system for normal operation.
PINPO
INT TEST V : DTC P1240, P1241, P1242
; SENSOR REFERENCE VOLTAGE MALFUNCTION,
HIGH/LOW VOLTAGE (THROTTLE SENSORS, FUEL TANK PRESSURE SENSOR)
TE S
T
CONDITIONS
D E
TAILS/RESULTS/ACTIONS
V
1
: CHECK THE REFERENCE VOLTAGE AT TH
E APP SENSOR/MECHANICAL GUARD SENSOR
Disc
onnect the APP sensor electrical connector, PI42.
1
Turn the ignition swi
t
ch to the ON
position.
2
Measure the voltage between PI
42,
pin 04 (UW) and GROUND.
3
Is th
e volt
age less than 5 volts?
Yes GO to V2
.
No
GO to V3
.
V2
: CHECK THE APP SENSOR/MECHA
NICAL GUARD SENSOR REFERENCE VOLTAGE CIRCUIT FOR HIGH
RESISTANCE
Di sc
onnect the battery negative terminal.
1
D
i
sconnect the ECM electrical connectors, EM10 and EM11.
2
Me
asure
the resistance between PI42, pin 04 (UW) and EM10, pin 21 (UW).
3
Me
asure
the resistance between PI42, pin 04 (UW) and EM11, pin 08 (UW).
4
Is either resi
stance greater
than 5 ohms?
Yes REPAIR the high resistance circui t. For additional information, refer to the wiring diagrams. CLEAR
the DTC. TEST the system for normal operation.
No GO to V3
.
V3
: CHECK THE APP SENSOR/MECHA
NICAL GUARD SENSOR REFERENCE VOLTAGE CIRCUIT FOR SHORT TO
HIGH VOLTAGE

Measure the voltage between FP 01
, pin 03 (UW) and GROUND.
4
Is th
e volt
age less than 5 volts?
Yes GO to V10
.
No
CHECK
for DTCs associated with
TP sensor, APP/mechanical guard sensor, or FTP sensor. INSTALL a
new sensor as indicated by the DTC. CLEAR the DTC. TEST the system for normal operation.
V
10: CHECK
THE FUEL TANK PRESSURE SENSOR
REFERENCE VOLTAGE CIRCUIT FOR HIGH RESISTANCE
Disc
onnect the battery negative terminal.
1
D
i
sconnect the ECM electrical connectors, EM10 and EM11.
2
Measure t

he resistance between FP01,
pin 03 (UW) and EM10, pin 21 (UW).
3
Measure t
he resistance between FP01,
pin 03 (UW) and EM11, pin 08 (UW).
4
Is either resistance greater
than 5 ohms?
Yes REPAIR the high resistance circui t. For additional information, refer to the wiring diagrams. CLEAR
the DTC. TEST the system for normal operation.
No GO to V11
.
V11: CHECK
THE FUEL TANK PRESSURE SENSOR REFE
RENCE VOLTAGE CIRCUIT FOR SHORT TO HIGH VOLTAGE
Re
connect the battery negative terminal.
1
Turn the ignition swi
t
ch to the ON
position.
2
Measure the voltage between FP 01
, pin 03 (UW) and GROUND.
3
Is th
e volt
age greater than 6 volts?
Yes REPAIR the short circuit. For addi tional information, refer to the wiring diagrams. CLEAR the DTC.
TEST the system for normal operation.
No GO to V12
.
V12: CHECK
THE FUEL TANK PRESSURE SENSOR
REFERENCE VOLTAGE CIRCUIT FOR SHORT TO GROUND
Turn the ignition swit
ch to the OFF
position.
1
Measure t
he resistance between
FP01, pin 03 (UW) and GROUND.
2
Is t
he resistance less than 10,000 ohms?
Yes REPAIR the short circuit. For addi tional information, refer to the wiring diagrams. CLEAR the DTC.
TEST the system for normal operation.
No CHECK for DTCs associated with TP sensor, APP/mechanical guard sensor, or FTP sensor. INSTALL a
new sensor as indicated by the DTC. CLEAR the DTC. TEST the system for normal operation.
PI
NPOINT TEST W : DTC P1243; SENSOR RE
FERENCE GROUND MALFUNCTION (THROTTLE
SENSORS, FUEL TANK PRESSURE SENSOR, ECT, IAT, IAT 2 SENSORS)
TE S
T
CONDITIONS
D E
TAILS/RESULTS/ACTIONS
W1: CHECK THE SENSO
R
REFERENCE
GROUND AT THE THROTTLE SENSORS
Disc
onne
ct the TP sensor electrical connector, PI06.
1
Meas
ure t
he resistance between PI06, pin 01 (BG) and GROUND.
2
Is th
e res
istance greater than 5 ohms?
Yes GO to W2
.
No
GO to W3
.
W2: CHECK TH
E THROTTLE SENSOR REFERENCE GROUND CIRCUIT FOR HIGH RESISTANCE
D
i
sconnect the ECM electrical connectors, EM10 and EM11.
1
Meas
ure t
he resistance between PI06,
pin 01 (BG) and EM10, pin 20 (BG).
2
Measure t
he resistance between PI06,
pin 01 (BG) and EM11, pin 12 (BG).
3
Is either resistance greater
than 5 ohms?
Yes REPAIR the high resistance circuit. For additional information, refer to the wiring diagrams. CLEAR the
DTC. TEST the system for normal operation.
No GO to W3
.
W3: CHECK THE SENSO R
REFERENCE GROUND AT
THE APP SENSOR/MECHANICAL GUARD SENSOR

Transmission Speed Sensors (Gear Shift Control)

Operation
There are two speed sensors within the transmission assembly; one on the input shaft or convertor turbine and the other on the output shaft.
Both sensors are of the inductive type and sense toothed wheels; the input wheel having 30 teeth and the output 36 teeth.

Temperature ( °C)Nominal Resistance (kOHM)
-20685
0812
20953
401107
601276
801458
1001653