Infiniti Q45 (FY33). Manual — part 150
SEF395W
SEF377U
SEF536P
SEF378U
SEF379U
DIAGNOSTIC PROCEDURE
If the trouble is duplicated after “Procedure for malfunction A
or C, perform “Procedure A” below. If the trouble is duplicated
after “Procedure for malfunction B or D”, perform “Procedure
B” on next page.
Procedure A
INSPECTION START
1. Turn ignition switch “OFF”.
2. Loosen and retighten engine ground
screws.
CHECK POWER SUPPLY.
1. Turn ignition switch “OFF”.
2. Disconnect mass air flow sensor har-
ness connector.
3. Turn ignition switch “ON”.
4. Check voltage between terminal
q
3
and
ground with CONSULT-II or tester.
Voltage: Battery positive voltage
OK
E
NG
Check the following.
I
Harness for open or
short between mass air
flow sensor and ECM
I
Harness for open or
short between mass air
flow sensor and ECM
relay
If NG, repair harness or
connector.
CHECK GROUND CIRCUIT.
1. Turn ignition switch “OFF”.
2. Disconnect ECM harness connector.
3. Check harness continuity between ter-
minal
q
2
and ECM terminal
q
62
.
Continuity should exist.
If OK, check harness for short to power.
OK
E
NG
Repair harness or connec-
tors.
CHECK INPUT SIGNAL CIRCUIT.
Check harness continuity between termi-
nal
q
1
and ECM terminal
q
65
.
Continuity should exist.
If OK, check harness for short to ground
and short to power.
OK
E
NG
Repair harness or connec-
tors.
CHECK COMPONENT
(Mass air flow sensor).
Refer to “COMPONENT INSPECTION”,
EC-131.
OK
E
NG
Replace mass air flow sen-
sor.
Perform “TROUBLE DIAGNOSIS FOR
INTERMITTENT INCIDENT”, EC-117.
INSPECTION END
GI
MA
EM
LC
FE
AT
PD
FA
RA
BR
ST
RS
BT
HA
EL
IDX
TROUBLE DIAGNOSIS FOR DTC P0100
Mass Air Flow Sensor (MAFS) (Cont’d)
H
H
H
H
H
H
H
EC-129
SEF395W
SEF377U
SEF536P
SEF378U
SEF379U
Procedure B
INSPECTION START
CHECK INTAKE SYSTEM
Check the followings for connection.
I
Air duct
I
Vacuum hoses
I
Intake air passage between intake air duct
to collector
If disconnected, reconnect the parts or repair.
OK
E
NG
Reconnect or repair.
1. Turn ignition switch “OFF”.
2. Loosen and retighten engine ground
screws.
CHECK POWER SUPPLY.
1. Turn ignition switch “OFF”.
2. Disconnect mass air flow sensor harness
connector.
3. Turn ignition switch “ON”.
4. Check voltage between terminal
q
3
and
ground with CONSULT-II or tester.
Voltage: Battery positive voltage
OK
E
NG
Check the following.
I
Harness for open or short
between mass air flow
sensor and ECM
I
Harness for open or short
between mass air flow
sensor and ECM relay
If NG, repair harness or con-
nector.
CHECK GROUND CIRCUIT.
1. Turn ignition switch “OFF”.
2. Disconnect ECM harness connector.
3. Check harness continuity between termi-
nal
q
2
and ECM terminal
q
62
.
Continuity should exist.
If OK, check harness for short to power.
OK
E
NG
Repair harness or connec-
tors.
CHECK INPUT SIGNAL CIRCUIT.
Check harness continuity between terminal
q
1
and ECM terminal
q
65
.
Continuity should exist.
If OK, check harness for short to ground and
short to power.
OK
E
NG
Repair harness or connec-
tors.
CHECK COMPONENT
(Mass air flow sensor).
Refer to “COMPONENT INSPECTION” on
next page.
OK
E
NG
Replace mass air flow sen-
sor.
Perform “TROUBLE DIAGNOSIS FOR
INTERMITTENT INCIDENT”, EC-117.
INSPECTION END
TROUBLE DIAGNOSIS FOR DTC P0100
Mass Air Flow Sensor (MAFS) (Cont’d)
H
H
H
H
H
H
H
H
EC-130
SEF743W
SEF301T
COMPONENT INSPECTION
Mass air flow sensor
1.
Turn ignition switch “ON”.
2.
Start engine and warm it up to normal operating temperature.
3.
Check voltage between ECM terminal
q
65
and ground.
Conditions
Voltage V
Ignition switch “ON” (Engine stopped.)
Less than 1.0
Idle (Engine is warmed-up to normal operating tem-
perature.)
1.0 - 1.7
2,500 rpm
Approximately 2.1
Idle to about 4,000 rpm*
1.0 - 1.7 to Approx. 4.0
*: Check for linear voltage rise in response to increase to about 4,000 rpm in engine
speed.
4.
If the voltage is out of specification, disconnect mass air flow
sensor harness connector and connect it again. Repeat above
check.
5.
If NG, remove mass air flow sensor from air duct. Check hot
film for damage or dust.
GI
MA
EM
LC
FE
AT
PD
FA
RA
BR
ST
RS
BT
HA
EL
IDX
TROUBLE DIAGNOSIS FOR DTC P0100
Mass Air Flow Sensor (MAFS) (Cont’d)
EC-131
SEF327V
Absolute Pressure Sensor
COMPONENT DESCRIPTION
The absolute pressure sensor is connected to the MAP/BARO
switch solenoid valve by a hose. The sensor detects ambient baro-
metric pressure and intake manifold pressure and sends the volt-
age signal to the ECM. As the pressure increases, the voltage
rises.
SEF946S
ON BOARD DIAGNOSIS LOGIC
Diagnostic Trouble
Code No.
Malfunction is detected when .
Check Items
(Possible Cause)
P0105
0803
A) An excessively low or high voltage from the sen-
sor is sent to ECM.
I
Harness or connectors
(Absolute pressure sensor circuit is open or
shorted.)
I
Absolute pressure sensor
B) A high voltage from the sensor is sent to ECM
under light load driving conditions.
I
Hoses
(Hoses between the intake manifold and absolute
pressure sensor are disconnected or clogged.)
I
Intake air leaks
I
MAP/BARO switch solenoid valve
I
Absolute pressure sensor
C) A low voltage from the sensor is sent to ECM
under heavy load driving conditions.
I
Absolute pressure sensor
DIAGNOSTIC TROUBLE CODE CONFIRMATION
PROCEDURE
Perform “Procedure for malfunction A” first. If the 1st trip DTC
cannot be confirmed, perform “Procedure for malfunction B”.
If the 1st trip DTC is not confirmed on “Procedure for malfunc-
tion B”, perform “Procedure for malfunction C”.
NOTE:
If “DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCE-
DURE” has been previously conducted, always turn ignition
switch “OFF” and wait at least 5 seconds before conducting
the next test.
CAUTION:
Always drive vehicle at a safe speed.
TROUBLE DIAGNOSIS FOR DTC P0105
EC-132
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