Infiniti QX4 (R50). Manual — part 172
Diagnostic Procedure
NBEC0057
1
INSPECTION START
Which malfunction (A, B, C, D or E) is duplicated?
MTBL0373
Type I or Type II
Type I
©
GO TO 3.
Type II
©
GO TO 2.
2
CHECK INTAKE SYSTEM
Check the following for connection.
I
Air duct
I
Vacuum hoses
I
Intake air passage between air duct to intake manifold collector
OK or NG
OK
©
GO TO 3.
NG
©
Reconnect the parts.
3
RETIGHTEN GROUND SCREWS
1. Turn ignition switch “OFF”.
2. Loosen and retighten engine ground screws.
SEF959Y
©
GO TO 4.
GI
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
DTC P0100 MASS AIR FLOW SENSOR (MAFS)
Diagnostic Procedure
EC-155
4
CHECK MAFS POWER SUPPLY CIRCUIT
1. Disconnect mass air flow sensor (MAFS) harness connector.
SEF960Y
2. Turn ignition switch “ON”.
3. Check voltage between MAFS terminals 2, 4 and ground with CONSULT-II or tester.
SEF297X
OK or NG
OK
©
GO TO 6.
NG
©
GO TO 5.
5
DETECT MALFUNCTIONING PART
Check the following.
I
Harness for open or short between ECM relay and mass air flow sensor
I
Harness for open or short between mass air flow sensor and ECM
©
Repair harness or connectors.
6
CHECK MAFS GROUND CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch “OFF”.
2. Disconnect ECM harness connector.
3. Check harness continuity between MAFS terminal 3 and ECM terminal 73.
Refer to Wiring Diagram.
Continuity should exist.
4. Also check harness for short to power.
OK or NG
OK
©
GO TO 7.
NG
©
Repair open circuit or short to power in harness or connectors.
DTC P0100 MASS AIR FLOW SENSOR (MAFS)
Diagnostic Procedure (Cont’d)
EC-156
7
CHECK MAFS INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Check harness continuity between MAFS terminal 1 and ECM terminal 61.
Refer to Wiring Diagram.
Continuity should exist.
2. Also check harness for short to ground and short to power.
OK or NG
OK
©
GO TO 8.
NG
©
Repair open circuit or short to ground or short to power in harness or connectors.
8
CHECK MASS AIR FLOW SENSOR
1. Reconnect harness connectors disconnected.
2. Start engine and warm it up to normal operating temperature.
3. Check voltage between ECM terminal 61 (Mass air flow sensor signal) and ground.
SEF298X
4. If the voltage is out of specification, disconnect MAFS harness connector and connect it again.
Then repeat above check.
OK or NG
OK
©
GO TO 9.
NG
©
Replace mass air flow sensor.
9
CHECK INTERMITTENT INCIDENT
Refer to “TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT”, EC-140.
©
INSPECTION END
GI
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
DTC P0100 MASS AIR FLOW SENSOR (MAFS)
Diagnostic Procedure (Cont’d)
EC-157
SEF052V
SEF946SB
Component Description
NBEC0725
The absolute pressure sensor detects ambient barometric pressure
and sends the voltage signal to the ECM. As the pressure
increases, the voltage rises.
ECM Terminals and Reference Value
NBEC0726
Specification data are reference values and are measured between each terminal and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM’s transistor. Use a ground other than ECM terminals, such as the ground.
TERMI-
NAL
NO.
WIRE
COLOR
ITEM
CONDITION
DATA (DC Voltage)
80
L/R
Absolute pressure sen-
sor
[Ignition switch “ON”]
Approximately 4.4V
111
P/B
Sensors’ power supply
[Ignition switch “ON”]
Approximately 5V
58
B/P
Sensors’ ground
[Engine is running]
I
Warm-up condition
I
Idle speed
Approximately 0V
On Board Diagnosis Logic
NBEC0727
Malfunction is detected when an excessively low or high voltage
from the sensor is sent to ECM.
DTC P0105 ABSOLUTE PRESSURE SENSOR
Component Description
EC-158
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